kevin/linux
1
Fork 0
Code
ef0aaf873e
linux/arch/tile/kernel/intvec_32.S
Chris Metcalf df29ccb6c0 arch/tile: allow nonatomic stores to interoperate with fast atomic syscalls 
This semantic was already true for atomic operations within the kernel,
and this change makes it true for the fast atomic syscalls (__NR_cmpxchg
and __NR_atomic_update) as well.  Previously, user-space had to use
the fast atomic syscalls exclusively to update memory, since raw stores
could lose a race with the atomic update code even when the atomic update
hadn't actually modified the value.

With this change, we no longer write back the value to memory if it
hasn't changed.  This allows certain types of idioms in user space to
work as expected, e.g. "atomic exchange" to acquire a spinlock, followed
by a raw store of zero to release the lock.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
2011-05-04 14:40:07 -04:00

1914 lines
52 KiB
ArmAsm
Raw Blame History

/*
* Copyright 2010 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*
* Linux interrupt vectors.
*/
#include <linux/linkage.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/unistd.h>
#include <asm/ptrace.h>
#include <asm/thread_info.h>
#include <asm/irqflags.h>
#include <asm/atomic.h>
#include <asm/asm-offsets.h>
#include <hv/hypervisor.h>
#include <arch/abi.h>
#include <arch/interrupts.h>
#include <arch/spr_def.h>
#ifdef CONFIG_PREEMPT
# error "No support for kernel preemption currently"
#endif
#define PTREGS_PTR(reg, ptreg) addli reg, sp, C_ABI_SAVE_AREA_SIZE + (ptreg)
#define PTREGS_OFFSET_SYSCALL PTREGS_OFFSET_REG(TREG_SYSCALL_NR)
#if !CHIP_HAS_WH64()
/* By making this an empty macro, we can use wh64 in the code. */
.macro wh64 reg
.endm
#endif
.macro push_reg reg, ptr=sp, delta=-4
{
sw \ptr, \reg
addli \ptr, \ptr, \delta
}
.endm
.macro pop_reg reg, ptr=sp, delta=4
{
lw \reg, \ptr
addli \ptr, \ptr, \delta
}
.endm
.macro pop_reg_zero reg, zreg, ptr=sp, delta=4
{
move \zreg, zero
lw \reg, \ptr
addi \ptr, \ptr, \delta
}
.endm
.macro push_extra_callee_saves reg
PTREGS_PTR(\reg, PTREGS_OFFSET_REG(51))
push_reg r51, \reg
push_reg r50, \reg
push_reg r49, \reg
push_reg r48, \reg
push_reg r47, \reg
push_reg r46, \reg
push_reg r45, \reg
push_reg r44, \reg
push_reg r43, \reg
push_reg r42, \reg
push_reg r41, \reg
push_reg r40, \reg
push_reg r39, \reg
push_reg r38, \reg
push_reg r37, \reg
push_reg r36, \reg
push_reg r35, \reg
push_reg r34, \reg, PTREGS_OFFSET_BASE - PTREGS_OFFSET_REG(34)
.endm
.macro panic str
.pushsection .rodata, "a"
1:
.asciz "\str"
.popsection
{
moveli r0, lo16(1b)
}
{
auli r0, r0, ha16(1b)
jal panic
}
.endm
#ifdef __COLLECT_LINKER_FEEDBACK__
.pushsection .text.intvec_feedback,"ax"
intvec_feedback:
.popsection
#endif
/*
* Default interrupt handler.
*
* vecnum is where we'll put this code.
* c_routine is the C routine we'll call.
*
* The C routine is passed two arguments:
* - A pointer to the pt_regs state.
* - The interrupt vector number.
*
* The "processing" argument specifies the code for processing
* the interrupt. Defaults to "handle_interrupt".
*/
.macro int_hand vecnum, vecname, c_routine, processing=handle_interrupt
.org (\vecnum << 8)
intvec_\vecname:
.ifc \vecnum, INT_SWINT_1
blz TREG_SYSCALL_NR_NAME, sys_cmpxchg
.endif
/* Temporarily save a register so we have somewhere to work. */
mtspr SPR_SYSTEM_SAVE_K_1, r0
mfspr r0, SPR_EX_CONTEXT_K_1
/* The cmpxchg code clears sp to force us to reset it here on fault. */
{
bz sp, 2f
andi r0, r0, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */
}
.ifc \vecnum, INT_DOUBLE_FAULT
/*
* For double-faults from user-space, fall through to the normal
* register save and stack setup path. Otherwise, it's the
* hypervisor giving us one last chance to dump diagnostics, and we
* branch to the kernel_double_fault routine to do so.
*/
bz r0, 1f
j _kernel_double_fault
1:
.else
/*
* If we're coming from user-space, then set sp to the top of
* the kernel stack. Otherwise, assume sp is already valid.
*/
{
bnz r0, 0f
move r0, sp
}
.endif
.ifc \c_routine, do_page_fault
/*
* The page_fault handler may be downcalled directly by the
* hypervisor even when Linux is running and has ICS set.
*
* In this case the contents of EX_CONTEXT_K_1 reflect the
* previous fault and can't be relied on to choose whether or
* not to reinitialize the stack pointer. So we add a test
* to see whether SYSTEM_SAVE_K_2 has the high bit set,
* and if so we don't reinitialize sp, since we must be coming
* from Linux. (In fact the precise case is !(val & ~1),
* but any Linux PC has to have the high bit set.)
*
* Note that the hypervisor *always* sets SYSTEM_SAVE_K_2 for
* any path that turns into a downcall to one of our TLB handlers.
*/
mfspr r0, SPR_SYSTEM_SAVE_K_2
{
blz r0, 0f /* high bit in S_S_1_2 is for a PC to use */
move r0, sp
}
.endif
2:
/*
* SYSTEM_SAVE_K_0 holds the cpu number in the low bits, and
* the current stack top in the higher bits. So we recover
* our stack top by just masking off the low bits, then
* point sp at the top aligned address on the actual stack page.
*/
mfspr r0, SPR_SYSTEM_SAVE_K_0
mm r0, r0, zero, LOG2_THREAD_SIZE, 31
0:
/*
* Align the stack mod 64 so we can properly predict what
* cache lines we need to write-hint to reduce memory fetch
* latency as we enter the kernel. The layout of memory is
* as follows, with cache line 0 at the lowest VA, and cache
* line 4 just below the r0 value this "andi" computes.
* Note that we never write to cache line 4, and we skip
* cache line 1 for syscalls.
*
* cache line 4: ptregs padding (two words)
* cache line 3: r46...lr, pc, ex1, faultnum, orig_r0, flags, pad
* cache line 2: r30...r45
* cache line 1: r14...r29
* cache line 0: 2 x frame, r0..r13
*/
andi r0, r0, -64
/*
* Push the first four registers on the stack, so that we can set
* them to vector-unique values before we jump to the common code.
*
* Registers are pushed on the stack as a struct pt_regs,
* with the sp initially just above the struct, and when we're
* done, sp points to the base of the struct, minus
* C_ABI_SAVE_AREA_SIZE, so we can directly jal to C code.
*
* This routine saves just the first four registers, plus the
* stack context so we can do proper backtracing right away,
* and defers to handle_interrupt to save the rest.
* The backtracer needs pc, ex1, lr, sp, r52, and faultnum.
*/
addli r0, r0, PTREGS_OFFSET_LR - (PTREGS_SIZE + KSTK_PTREGS_GAP)
wh64 r0 /* cache line 3 */
{
sw r0, lr
addli r0, r0, PTREGS_OFFSET_SP - PTREGS_OFFSET_LR
}
{
sw r0, sp
addli sp, r0, PTREGS_OFFSET_REG(52) - PTREGS_OFFSET_SP
}
{
sw sp, r52
addli sp, sp, PTREGS_OFFSET_REG(1) - PTREGS_OFFSET_REG(52)
}
wh64 sp /* cache line 0 */
{
sw sp, r1
addli sp, sp, PTREGS_OFFSET_REG(2) - PTREGS_OFFSET_REG(1)
}
{
sw sp, r2
addli sp, sp, PTREGS_OFFSET_REG(3) - PTREGS_OFFSET_REG(2)
}
{
sw sp, r3
addli sp, sp, PTREGS_OFFSET_PC - PTREGS_OFFSET_REG(3)
}
mfspr r0, SPR_EX_CONTEXT_K_0
.ifc \processing,handle_syscall
/*
* Bump the saved PC by one bundle so that when we return, we won't
* execute the same swint instruction again. We need to do this while
* we're in the critical section.
*/
addi r0, r0, 8
.endif
{
sw sp, r0
addli sp, sp, PTREGS_OFFSET_EX1 - PTREGS_OFFSET_PC
}
mfspr r0, SPR_EX_CONTEXT_K_1
{
sw sp, r0
addi sp, sp, PTREGS_OFFSET_FAULTNUM - PTREGS_OFFSET_EX1
/*
* Use r0 for syscalls so it's a temporary; use r1 for interrupts
* so that it gets passed through unchanged to the handler routine.
* Note that the .if conditional confusingly spans bundles.
*/
.ifc \processing,handle_syscall
movei r0, \vecnum
}
{
sw sp, r0
.else
movei r1, \vecnum
}
{
sw sp, r1
.endif
addli sp, sp, PTREGS_OFFSET_REG(0) - PTREGS_OFFSET_FAULTNUM
}
mfspr r0, SPR_SYSTEM_SAVE_K_1 /* Original r0 */
{
sw sp, r0
addi sp, sp, -PTREGS_OFFSET_REG(0) - 4
}
{
sw sp, zero /* write zero into "Next SP" frame pointer */
addi sp, sp, -4 /* leave SP pointing at bottom of frame */
}
.ifc \processing,handle_syscall
j handle_syscall
.else
/*
* Capture per-interrupt SPR context to registers.
* We overload the meaning of r3 on this path such that if its bit 31
* is set, we have to mask all interrupts including NMIs before
* clearing the interrupt critical section bit.
* See discussion below at "finish_interrupt_save".
*/
.ifc \c_routine, do_page_fault
mfspr r2, SPR_SYSTEM_SAVE_K_3 /* address of page fault */
mfspr r3, SPR_SYSTEM_SAVE_K_2 /* info about page fault */
.else
.ifc \vecnum, INT_DOUBLE_FAULT
{
mfspr r2, SPR_SYSTEM_SAVE_K_2 /* double fault info from HV */
movei r3, 0
}
.else
.ifc \c_routine, do_trap
{
mfspr r2, GPV_REASON
movei r3, 0
}
.else
.ifc \c_routine, op_handle_perf_interrupt
{
mfspr r2, PERF_COUNT_STS
movei r3, -1 /* not used, but set for consistency */
}
.else
#if CHIP_HAS_AUX_PERF_COUNTERS()
.ifc \c_routine, op_handle_aux_perf_interrupt
{
mfspr r2, AUX_PERF_COUNT_STS
movei r3, -1 /* not used, but set for consistency */
}
.else
#endif
movei r3, 0
#if CHIP_HAS_AUX_PERF_COUNTERS()
.endif
#endif
.endif
.endif
.endif
.endif
/* Put function pointer in r0 */
moveli r0, lo16(\c_routine)
{
auli r0, r0, ha16(\c_routine)
j \processing
}
.endif
ENDPROC(intvec_\vecname)
#ifdef __COLLECT_LINKER_FEEDBACK__
.pushsection .text.intvec_feedback,"ax"
.org (\vecnum << 5)
FEEDBACK_ENTER_EXPLICIT(intvec_\vecname, .intrpt1, 1 << 8)
jrp lr
.popsection
#endif
.endm
/*
* Save the rest of the registers that we didn't save in the actual
* vector itself. We can't use r0-r10 inclusive here.
*/
.macro finish_interrupt_save, function
/* If it's a syscall, save a proper orig_r0, otherwise just zero. */
PTREGS_PTR(r52, PTREGS_OFFSET_ORIG_R0)
{
.ifc \function,handle_syscall
sw r52, r0
.else
sw r52, zero
.endif
PTREGS_PTR(r52, PTREGS_OFFSET_TP)
}
/*
* For ordinary syscalls, we save neither caller- nor callee-
* save registers, since the syscall invoker doesn't expect the
* caller-saves to be saved, and the called kernel functions will
* take care of saving the callee-saves for us.
*
* For interrupts we save just the caller-save registers. Saving
* them is required (since the "caller" can't save them). Again,
* the called kernel functions will restore the callee-save
* registers for us appropriately.
*
* On return, we normally restore nothing special for syscalls,
* and just the caller-save registers for interrupts.
*
* However, there are some important caveats to all this:
*
* - We always save a few callee-save registers to give us
* some scratchpad registers to carry across function calls.
*
* - fork/vfork/etc require us to save all the callee-save
* registers, which we do in PTREGS_SYSCALL_ALL_REGS, below.
*
* - We always save r0..r5 and r10 for syscalls, since we need
* to reload them a bit later for the actual kernel call, and
* since we might need them for -ERESTARTNOINTR, etc.
*
* - Before invoking a signal handler, we save the unsaved
* callee-save registers so they are visible to the
* signal handler or any ptracer.
*
* - If the unsaved callee-save registers are modified, we set
* a bit in pt_regs so we know to reload them from pt_regs
* and not just rely on the kernel function unwinding.
* (Done for ptrace register writes and SA_SIGINFO handler.)
*/
{
sw r52, tp
PTREGS_PTR(r52, PTREGS_OFFSET_REG(33))
}
wh64 r52 /* cache line 2 */
push_reg r33, r52
push_reg r32, r52
push_reg r31, r52
.ifc \function,handle_syscall
push_reg r30, r52, PTREGS_OFFSET_SYSCALL - PTREGS_OFFSET_REG(30)
push_reg TREG_SYSCALL_NR_NAME, r52, \
PTREGS_OFFSET_REG(5) - PTREGS_OFFSET_SYSCALL
.else
push_reg r30, r52, PTREGS_OFFSET_REG(29) - PTREGS_OFFSET_REG(30)
wh64 r52 /* cache line 1 */
push_reg r29, r52
push_reg r28, r52
push_reg r27, r52
push_reg r26, r52
push_reg r25, r52
push_reg r24, r52
push_reg r23, r52
push_reg r22, r52
push_reg r21, r52
push_reg r20, r52
push_reg r19, r52
push_reg r18, r52
push_reg r17, r52
push_reg r16, r52
push_reg r15, r52
push_reg r14, r52
push_reg r13, r52
push_reg r12, r52
push_reg r11, r52
push_reg r10, r52
push_reg r9, r52
push_reg r8, r52
push_reg r7, r52
push_reg r6, r52
.endif
push_reg r5, r52
sw r52, r4
/* Load tp with our per-cpu offset. */
#ifdef CONFIG_SMP
{
mfspr r20, SPR_SYSTEM_SAVE_K_0
moveli r21, lo16(__per_cpu_offset)
}
{
auli r21, r21, ha16(__per_cpu_offset)
mm r20, r20, zero, 0, LOG2_THREAD_SIZE-1
}
s2a r20, r20, r21
lw tp, r20
#else
move tp, zero
#endif
/*
* If we will be returning to the kernel, we will need to
* reset the interrupt masks to the state they had before.
* Set DISABLE_IRQ in flags iff we came from PL1 with irqs disabled.
* We load flags in r32 here so we can jump to .Lrestore_regs
* directly after do_page_fault_ics() if necessary.
*/
mfspr r32, SPR_EX_CONTEXT_K_1
{
andi r32, r32, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */
PTREGS_PTR(r21, PTREGS_OFFSET_FLAGS)
}
bzt r32, 1f /* zero if from user space */
IRQS_DISABLED(r32) /* zero if irqs enabled */
#if PT_FLAGS_DISABLE_IRQ != 1
# error Value of IRQS_DISABLED used to set PT_FLAGS_DISABLE_IRQ; fix
#endif
1:
.ifnc \function,handle_syscall
/* Record the fact that we saved the caller-save registers above. */
ori r32, r32, PT_FLAGS_CALLER_SAVES
.endif
sw r21, r32
#ifdef __COLLECT_LINKER_FEEDBACK__
/*
* Notify the feedback routines that we were in the
* appropriate fixed interrupt vector area. Note that we
* still have ICS set at this point, so we can't invoke any
* atomic operations or we will panic. The feedback
* routines internally preserve r0..r10 and r30 up.
*/
.ifnc \function,handle_syscall
shli r20, r1, 5
.else
moveli r20, INT_SWINT_1 << 5
.endif
addli r20, r20, lo16(intvec_feedback)
auli r20, r20, ha16(intvec_feedback)
jalr r20
/* And now notify the feedback routines that we are here. */
FEEDBACK_ENTER(\function)
#endif
/*
* we've captured enough state to the stack (including in
* particular our EX_CONTEXT state) that we can now release
* the interrupt critical section and replace it with our
* standard "interrupts disabled" mask value. This allows
* synchronous interrupts (and profile interrupts) to punch
* through from this point onwards.
*
* If bit 31 of r3 is set during a non-NMI interrupt, we know we
* are on the path where the hypervisor has punched through our
* ICS with a page fault, so we call out to do_page_fault_ics()
* to figure out what to do with it. If the fault was in
* an atomic op, we unlock the atomic lock, adjust the
* saved register state a little, and return "zero" in r4,
* falling through into the normal page-fault interrupt code.
* If the fault was in a kernel-space atomic operation, then
* do_page_fault_ics() resolves it itself, returns "one" in r4,
* and as a result goes directly to restoring registers and iret,
* without trying to adjust the interrupt masks at all.
* The do_page_fault_ics() API involves passing and returning
* a five-word struct (in registers) to avoid writing the
* save and restore code here.
*/
.ifc \function,handle_nmi
IRQ_DISABLE_ALL(r20)
.else
.ifnc \function,handle_syscall
bgezt r3, 1f
{
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
jal do_page_fault_ics
}
FEEDBACK_REENTER(\function)
bzt r4, 1f
j .Lrestore_regs
1:
.endif
IRQ_DISABLE(r20, r21)
.endif
mtspr INTERRUPT_CRITICAL_SECTION, zero
#if CHIP_HAS_WH64()
/*
* Prepare the first 256 stack bytes to be rapidly accessible
* without having to fetch the background data. We don't really
* know how far to write-hint, but kernel stacks generally
* aren't that big, and write-hinting here does take some time.
*/
addi r52, sp, -64
{
wh64 r52
addi r52, r52, -64
}
{
wh64 r52
addi r52, r52, -64
}
{
wh64 r52
addi r52, r52, -64
}
wh64 r52
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
.ifnc \function,handle_nmi
/*
* We finally have enough state set up to notify the irq
* tracing code that irqs were disabled on entry to the handler.
* The TRACE_IRQS_OFF call clobbers registers r0-r29.
* For syscalls, we already have the register state saved away
* on the stack, so we don't bother to do any register saves here,
* and later we pop the registers back off the kernel stack.
* For interrupt handlers, save r0-r3 in callee-saved registers.
*/
.ifnc \function,handle_syscall
{ move r30, r0; move r31, r1 }
{ move r32, r2; move r33, r3 }
.endif
TRACE_IRQS_OFF
.ifnc \function,handle_syscall
{ move r0, r30; move r1, r31 }
{ move r2, r32; move r3, r33 }
.endif
.endif
#endif
.endm
.macro check_single_stepping, kind, not_single_stepping
/*
* Check for single stepping in user-level priv
* kind can be "normal", "ill", or "syscall"
* At end, if fall-thru
* r29: thread_info->step_state
* r28: &pt_regs->pc
* r27: pt_regs->pc
* r26: thread_info->step_state->buffer
*/
/* Check for single stepping */
GET_THREAD_INFO(r29)
{
/* Get pointer to field holding step state */
addi r29, r29, THREAD_INFO_STEP_STATE_OFFSET
/* Get pointer to EX1 in register state */
PTREGS_PTR(r27, PTREGS_OFFSET_EX1)
}
{
/* Get pointer to field holding PC */
PTREGS_PTR(r28, PTREGS_OFFSET_PC)
/* Load the pointer to the step state */
lw r29, r29
}
/* Load EX1 */
lw r27, r27
{
/* Points to flags */
addi r23, r29, SINGLESTEP_STATE_FLAGS_OFFSET
/* No single stepping if there is no step state structure */
bzt r29, \not_single_stepping
}
{
/* mask off ICS and any other high bits */
andi r27, r27, SPR_EX_CONTEXT_1_1__PL_MASK
/* Load pointer to single step instruction buffer */
lw r26, r29
}
/* Check priv state */
bnz r27, \not_single_stepping
/* Get flags */
lw r22, r23
{
/* Branch if single-step mode not enabled */
bbnst r22, \not_single_stepping
/* Clear enabled flag */
andi r22, r22, ~SINGLESTEP_STATE_MASK_IS_ENABLED
}
.ifc \kind,normal
{
/* Load PC */
lw r27, r28
/* Point to the entry containing the original PC */
addi r24, r29, SINGLESTEP_STATE_ORIG_PC_OFFSET
}
{
/* Disable single stepping flag */
sw r23, r22
}
{
/* Get the original pc */
lw r24, r24
/* See if the PC is at the start of the single step buffer */
seq r25, r26, r27
}
/*
* NOTE: it is really expected that the PC be in the single step buffer
* at this point
*/
bzt r25, \not_single_stepping
/* Restore the original PC */
sw r28, r24
.else
.ifc \kind,syscall
{
/* Load PC */
lw r27, r28
/* Point to the entry containing the next PC */
addi r24, r29, SINGLESTEP_STATE_NEXT_PC_OFFSET
}
{
/* Increment the stopped PC by the bundle size */
addi r26, r26, 8
/* Disable single stepping flag */
sw r23, r22
}
{
/* Get the next pc */
lw r24, r24
/*
* See if the PC is one bundle past the start of the
* single step buffer
*/
seq r25, r26, r27
}
{
/*
* NOTE: it is really expected that the PC be in the
* single step buffer at this point
*/
bzt r25, \not_single_stepping
}
/* Set to the next PC */
sw r28, r24
.else
{
/* Point to 3rd bundle in buffer */
addi r25, r26, 16
/* Load PC */
lw r27, r28
}
{
/* Disable single stepping flag */
sw r23, r22
/* See if the PC is in the single step buffer */
slte_u r24, r26, r27
}
{
slte_u r25, r27, r25
/*
* NOTE: it is really expected that the PC be in the
* single step buffer at this point
*/
bzt r24, \not_single_stepping
}
bzt r25, \not_single_stepping
.endif
.endif
.endm
/*
* Redispatch a downcall.
*/
.macro dc_dispatch vecnum, vecname
.org (\vecnum << 8)
intvec_\vecname:
j hv_downcall_dispatch
ENDPROC(intvec_\vecname)
.endm
/*
* Common code for most interrupts. The C function we're eventually
* going to is in r0, and the faultnum is in r1; the original
* values for those registers are on the stack.
*/
.pushsection .text.handle_interrupt,"ax"
handle_interrupt:
finish_interrupt_save handle_interrupt
/*
* Check for if we are single stepping in user level. If so, then
* we need to restore the PC.
*/
check_single_stepping normal, .Ldispatch_interrupt
.Ldispatch_interrupt:
/* Jump to the C routine; it should enable irqs as soon as possible. */
{
jalr r0
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
}
FEEDBACK_REENTER(handle_interrupt)
{
movei r30, 0 /* not an NMI */
j interrupt_return
}
STD_ENDPROC(handle_interrupt)
/*
* This routine takes a boolean in r30 indicating if this is an NMI.
* If so, we also expect a boolean in r31 indicating whether to
* re-enable the oprofile interrupts.
*/
STD_ENTRY(interrupt_return)
/* If we're resuming to kernel space, don't check thread flags. */
{
bnz r30, .Lrestore_all /* NMIs don't special-case user-space */
PTREGS_PTR(r29, PTREGS_OFFSET_EX1)
}
lw r29, r29
andi r29, r29, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */
{
bzt r29, .Lresume_userspace
PTREGS_PTR(r29, PTREGS_OFFSET_PC)
}
/* If we're resuming to _cpu_idle_nap, bump PC forward by 8. */
{
lw r28, r29
moveli r27, lo16(_cpu_idle_nap)
}
{
auli r27, r27, ha16(_cpu_idle_nap)
}
{
seq r27, r27, r28
}
{
bbns r27, .Lrestore_all
addi r28, r28, 8
}
sw r29, r28
j .Lrestore_all
.Lresume_userspace:
FEEDBACK_REENTER(interrupt_return)
/*
* Disable interrupts so as to make sure we don't
* miss an interrupt that sets any of the thread flags (like
* need_resched or sigpending) between sampling and the iret.
* Routines like schedule() or do_signal() may re-enable
* interrupts before returning.
*/
IRQ_DISABLE(r20, r21)
TRACE_IRQS_OFF /* Note: clobbers registers r0-r29 */
/* Get base of stack in r32; note r30/31 are used as arguments here. */
GET_THREAD_INFO(r32)
/* Check to see if there is any work to do before returning to user. */
{
addi r29, r32, THREAD_INFO_FLAGS_OFFSET
moveli r1, lo16(_TIF_ALLWORK_MASK)
}
{
lw r29, r29
auli r1, r1, ha16(_TIF_ALLWORK_MASK)
}
and r1, r29, r1
bzt r1, .Lrestore_all
/*
* Make sure we have all the registers saved for signal
* handling or single-step. Call out to C code to figure out
* exactly what we need to do for each flag bit, then if
* necessary, reload the flags and recheck.
*/
push_extra_callee_saves r0
{
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
jal do_work_pending
}
bnz r0, .Lresume_userspace
/*
* In the NMI case we
* omit the call to single_process_check_nohz, which normally checks
* to see if we should start or stop the scheduler tick, because
* we can't call arbitrary Linux code from an NMI context.
* We always call the homecache TLB deferral code to re-trigger
* the deferral mechanism.
*
* The other chunk of responsibility this code has is to reset the
* interrupt masks appropriately to reset irqs and NMIs. We have
* to call TRACE_IRQS_OFF and TRACE_IRQS_ON to support all the
* lockdep-type stuff, but we can't set ICS until afterwards, since
* ICS can only be used in very tight chunks of code to avoid
* tripping over various assertions that it is off.
*
* (There is what looks like a window of vulnerability here since
* we might take a profile interrupt between the two SPR writes
* that set the mask, but since we write the low SPR word first,
* and our interrupt entry code checks the low SPR word, any
* profile interrupt will actually disable interrupts in both SPRs
* before returning, which is OK.)
*/
.Lrestore_all:
PTREGS_PTR(r0, PTREGS_OFFSET_EX1)
{
lw r0, r0
PTREGS_PTR(r32, PTREGS_OFFSET_FLAGS)
}
{
andi r0, r0, SPR_EX_CONTEXT_1_1__PL_MASK
lw r32, r32
}
bnz r0, 1f
j 2f
#if PT_FLAGS_DISABLE_IRQ != 1
# error Assuming PT_FLAGS_DISABLE_IRQ == 1 so we can use bbnst below
#endif
1: bbnst r32, 2f
IRQ_DISABLE(r20,r21)
TRACE_IRQS_OFF
movei r0, 1
mtspr INTERRUPT_CRITICAL_SECTION, r0
bzt r30, .Lrestore_regs
j 3f
2: TRACE_IRQS_ON
movei r0, 1
mtspr INTERRUPT_CRITICAL_SECTION, r0
IRQ_ENABLE(r20, r21)
bzt r30, .Lrestore_regs
3:
/*
* We now commit to returning from this interrupt, since we will be
* doing things like setting EX_CONTEXT SPRs and unwinding the stack
* frame. No calls should be made to any other code after this point.
* This code should only be entered with ICS set.
* r32 must still be set to ptregs.flags.
* We launch loads to each cache line separately first, so we can
* get some parallelism out of the memory subsystem.
* We start zeroing caller-saved registers throughout, since
* that will save some cycles if this turns out to be a syscall.
*/
.Lrestore_regs:
FEEDBACK_REENTER(interrupt_return) /* called from elsewhere */
/*
* Rotate so we have one high bit and one low bit to test.
* - low bit says whether to restore all the callee-saved registers,
* or just r30-r33, and r52 up.
* - high bit (i.e. sign bit) says whether to restore all the
* caller-saved registers, or just r0.
*/
#if PT_FLAGS_CALLER_SAVES != 2 || PT_FLAGS_RESTORE_REGS != 4
# error Rotate trick does not work :-)
#endif
{
rli r20, r32, 30
PTREGS_PTR(sp, PTREGS_OFFSET_REG(0))
}
/*
* Load cache lines 0, 2, and 3 in that order, then use
* the last loaded value, which makes it likely that the other
* cache lines have also loaded, at which point we should be
* able to safely read all the remaining words on those cache
* lines without waiting for the memory subsystem.
*/
pop_reg_zero r0, r28, sp, PTREGS_OFFSET_REG(30) - PTREGS_OFFSET_REG(0)
pop_reg_zero r30, r2, sp, PTREGS_OFFSET_PC - PTREGS_OFFSET_REG(30)
pop_reg_zero r21, r3, sp, PTREGS_OFFSET_EX1 - PTREGS_OFFSET_PC
pop_reg_zero lr, r4, sp, PTREGS_OFFSET_REG(52) - PTREGS_OFFSET_EX1
{
mtspr SPR_EX_CONTEXT_K_0, r21
move r5, zero
}
{
mtspr SPR_EX_CONTEXT_K_1, lr
andi lr, lr, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */
}
/* Restore callee-saveds that we actually use. */
pop_reg_zero r52, r6, sp, PTREGS_OFFSET_REG(31) - PTREGS_OFFSET_REG(52)
pop_reg_zero r31, r7
pop_reg_zero r32, r8
pop_reg_zero r33, r9, sp, PTREGS_OFFSET_REG(29) - PTREGS_OFFSET_REG(33)
/*
* If we modified other callee-saveds, restore them now.
* This is rare, but could be via ptrace or signal handler.
*/
{
move r10, zero
bbs r20, .Lrestore_callees
}
.Lcontinue_restore_regs:
/* Check if we're returning from a syscall. */
{
move r11, zero
blzt r20, 1f /* no, so go restore callee-save registers */
}
/*
* Check if we're returning to userspace.
* Note that if we're not, we don't worry about zeroing everything.
*/
{
addli sp, sp, PTREGS_OFFSET_LR - PTREGS_OFFSET_REG(29)
bnz lr, .Lkernel_return
}
/*
* On return from syscall, we've restored r0 from pt_regs, but we
* clear the remainder of the caller-saved registers. We could
* restore the syscall arguments, but there's not much point,
* and it ensures user programs aren't trying to use the
* caller-saves if we clear them, as well as avoiding leaking
* kernel pointers into userspace.
*/
pop_reg_zero lr, r12, sp, PTREGS_OFFSET_TP - PTREGS_OFFSET_LR
pop_reg_zero tp, r13, sp, PTREGS_OFFSET_SP - PTREGS_OFFSET_TP
{
lw sp, sp
move r14, zero
move r15, zero
}
{ move r16, zero; move r17, zero }
{ move r18, zero; move r19, zero }
{ move r20, zero; move r21, zero }
{ move r22, zero; move r23, zero }
{ move r24, zero; move r25, zero }
{ move r26, zero; move r27, zero }
/* Set r1 to errno if we are returning an error, otherwise zero. */
{
moveli r29, 4096
sub r1, zero, r0
}
slt_u r29, r1, r29
{
mnz r1, r29, r1
move r29, zero
}
iret
/*
* Not a syscall, so restore caller-saved registers.
* First kick off a load for cache line 1, which we're touching
* for the first time here.
*/
.align 64
1: pop_reg r29, sp, PTREGS_OFFSET_REG(1) - PTREGS_OFFSET_REG(29)
pop_reg r1
pop_reg r2
pop_reg r3
pop_reg r4
pop_reg r5
pop_reg r6
pop_reg r7
pop_reg r8
pop_reg r9
pop_reg r10
pop_reg r11
pop_reg r12
pop_reg r13
pop_reg r14
pop_reg r15
pop_reg r16
pop_reg r17
pop_reg r18
pop_reg r19
pop_reg r20
pop_reg r21
pop_reg r22
pop_reg r23
pop_reg r24
pop_reg r25
pop_reg r26
pop_reg r27
pop_reg r28, sp, PTREGS_OFFSET_LR - PTREGS_OFFSET_REG(28)
/* r29 already restored above */
bnz lr, .Lkernel_return
pop_reg lr, sp, PTREGS_OFFSET_TP - PTREGS_OFFSET_LR
pop_reg tp, sp, PTREGS_OFFSET_SP - PTREGS_OFFSET_TP
lw sp, sp
iret
/*
* We can't restore tp when in kernel mode, since a thread might
* have migrated from another cpu and brought a stale tp value.
*/
.Lkernel_return:
pop_reg lr, sp, PTREGS_OFFSET_SP - PTREGS_OFFSET_LR
lw sp, sp
iret
/* Restore callee-saved registers from r34 to r51. */
.Lrestore_callees:
addli sp, sp, PTREGS_OFFSET_REG(34) - PTREGS_OFFSET_REG(29)
pop_reg r34
pop_reg r35
pop_reg r36
pop_reg r37
pop_reg r38
pop_reg r39
pop_reg r40
pop_reg r41
pop_reg r42
pop_reg r43
pop_reg r44
pop_reg r45
pop_reg r46
pop_reg r47
pop_reg r48
pop_reg r49
pop_reg r50
pop_reg r51, sp, PTREGS_OFFSET_REG(29) - PTREGS_OFFSET_REG(51)
j .Lcontinue_restore_regs
STD_ENDPROC(interrupt_return)
/*
* Some interrupts don't check for single stepping
*/
.pushsection .text.handle_interrupt_no_single_step,"ax"
handle_interrupt_no_single_step:
finish_interrupt_save handle_interrupt_no_single_step
{
jalr r0
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
}
FEEDBACK_REENTER(handle_interrupt_no_single_step)
{
movei r30, 0 /* not an NMI */
j interrupt_return
}
STD_ENDPROC(handle_interrupt_no_single_step)
/*
* "NMI" interrupts mask ALL interrupts before calling the
* handler, and don't check thread flags, etc., on the way
* back out. In general, the only things we do here for NMIs
* are the register save/restore, fixing the PC if we were
* doing single step, and the dataplane kernel-TLB management.
* We don't (for example) deal with start/stop of the sched tick.
*/
.pushsection .text.handle_nmi,"ax"
handle_nmi:
finish_interrupt_save handle_nmi
check_single_stepping normal, .Ldispatch_nmi
.Ldispatch_nmi:
{
jalr r0
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
}
FEEDBACK_REENTER(handle_nmi)
j interrupt_return
STD_ENDPROC(handle_nmi)
/*
* Parallel code for syscalls to handle_interrupt.
*/
.pushsection .text.handle_syscall,"ax"
handle_syscall:
finish_interrupt_save handle_syscall
/*
* Check for if we are single stepping in user level. If so, then
* we need to restore the PC.
*/
check_single_stepping syscall, .Ldispatch_syscall
.Ldispatch_syscall:
/* Enable irqs. */
TRACE_IRQS_ON
IRQ_ENABLE(r20, r21)
/* Bump the counter for syscalls made on this tile. */
moveli r20, lo16(irq_stat + IRQ_CPUSTAT_SYSCALL_COUNT_OFFSET)
auli r20, r20, ha16(irq_stat + IRQ_CPUSTAT_SYSCALL_COUNT_OFFSET)
add r20, r20, tp
lw r21, r20
addi r21, r21, 1
sw r20, r21
/* Trace syscalls, if requested. */
GET_THREAD_INFO(r31)
addi r31, r31, THREAD_INFO_FLAGS_OFFSET
lw r30, r31
andi r30, r30, _TIF_SYSCALL_TRACE
bzt r30, .Lrestore_syscall_regs
jal do_syscall_trace
FEEDBACK_REENTER(handle_syscall)
/*
* We always reload our registers from the stack at this
* point. They might be valid, if we didn't build with
* TRACE_IRQFLAGS, and this isn't a dataplane tile, and we're not
* doing syscall tracing, but there are enough cases now that it
* seems simplest just to do the reload unconditionally.
*/
.Lrestore_syscall_regs:
PTREGS_PTR(r11, PTREGS_OFFSET_REG(0))
pop_reg r0, r11
pop_reg r1, r11
pop_reg r2, r11
pop_reg r3, r11
pop_reg r4, r11
pop_reg r5, r11, PTREGS_OFFSET_SYSCALL - PTREGS_OFFSET_REG(5)
pop_reg TREG_SYSCALL_NR_NAME, r11
/* Ensure that the syscall number is within the legal range. */
moveli r21, __NR_syscalls
{
slt_u r21, TREG_SYSCALL_NR_NAME, r21
moveli r20, lo16(sys_call_table)
}
{
bbns r21, .Linvalid_syscall
auli r20, r20, ha16(sys_call_table)
}
s2a r20, TREG_SYSCALL_NR_NAME, r20
lw r20, r20
/* Jump to syscall handler. */
jalr r20
.Lhandle_syscall_link: /* value of "lr" after "jalr r20" above */
/*
* Write our r0 onto the stack so it gets restored instead
* of whatever the user had there before.
*/
PTREGS_PTR(r29, PTREGS_OFFSET_REG(0))
sw r29, r0
.Lsyscall_sigreturn_skip:
FEEDBACK_REENTER(handle_syscall)
/* Do syscall trace again, if requested. */
lw r30, r31
andi r30, r30, _TIF_SYSCALL_TRACE
bzt r30, 1f
jal do_syscall_trace
FEEDBACK_REENTER(handle_syscall)
1: j .Lresume_userspace /* jump into middle of interrupt_return */
.Linvalid_syscall:
/* Report an invalid syscall back to the user program */
{
PTREGS_PTR(r29, PTREGS_OFFSET_REG(0))
movei r28, -ENOSYS
}
sw r29, r28
j .Lresume_userspace /* jump into middle of interrupt_return */
STD_ENDPROC(handle_syscall)
/* Return the address for oprofile to suppress in backtraces. */
STD_ENTRY_SECTION(handle_syscall_link_address, .text.handle_syscall)
lnk r0
{
addli r0, r0, .Lhandle_syscall_link - .
jrp lr
}
STD_ENDPROC(handle_syscall_link_address)
STD_ENTRY(ret_from_fork)
jal sim_notify_fork
jal schedule_tail
FEEDBACK_REENTER(ret_from_fork)
j .Lresume_userspace /* jump into middle of interrupt_return */
STD_ENDPROC(ret_from_fork)
/*
* Code for ill interrupt.
*/
.pushsection .text.handle_ill,"ax"
handle_ill:
finish_interrupt_save handle_ill
/*
* Check for if we are single stepping in user level. If so, then
* we need to restore the PC.
*/
check_single_stepping ill, .Ldispatch_normal_ill
{
/* See if the PC is the 1st bundle in the buffer */
seq r25, r27, r26
/* Point to the 2nd bundle in the buffer */
addi r26, r26, 8
}
{
/* Point to the original pc */
addi r24, r29, SINGLESTEP_STATE_ORIG_PC_OFFSET
/* Branch if the PC is the 1st bundle in the buffer */
bnz r25, 3f
}
{
/* See if the PC is the 2nd bundle of the buffer */
seq r25, r27, r26
/* Set PC to next instruction */
addi r24, r29, SINGLESTEP_STATE_NEXT_PC_OFFSET
}
{
/* Point to flags */
addi r25, r29, SINGLESTEP_STATE_FLAGS_OFFSET
/* Branch if PC is in the second bundle */
bz r25, 2f
}
/* Load flags */
lw r25, r25
{
/*
* Get the offset for the register to restore
* Note: the lower bound is 2, so we have implicit scaling by 4.
* No multiplication of the register number by the size of a register
* is needed.
*/
mm r27, r25, zero, SINGLESTEP_STATE_TARGET_LB, \
SINGLESTEP_STATE_TARGET_UB
/* Mask Rewrite_LR */
andi r25, r25, SINGLESTEP_STATE_MASK_UPDATE
}
{
addi r29, r29, SINGLESTEP_STATE_UPDATE_VALUE_OFFSET
/* Don't rewrite temp register */
bz r25, 3f
}
{
/* Get the temp value */
lw r29, r29
/* Point to where the register is stored */
add r27, r27, sp
}
/* Add in the C ABI save area size to the register offset */
addi r27, r27, C_ABI_SAVE_AREA_SIZE
/* Restore the user's register with the temp value */
sw r27, r29
j 3f
2:
/* Must be in the third bundle */
addi r24, r29, SINGLESTEP_STATE_BRANCH_NEXT_PC_OFFSET
3:
/* set PC and continue */
lw r26, r24
sw r28, r26
/*
* Clear TIF_SINGLESTEP to prevent recursion if we execute an ill.
* The normal non-arch flow redundantly clears TIF_SINGLESTEP, but we
* need to clear it here and can't really impose on all other arches.
* So what's another write between friends?
*/
GET_THREAD_INFO(r0)
addi r1, r0, THREAD_INFO_FLAGS_OFFSET
{
lw r2, r1
addi r0, r0, THREAD_INFO_TASK_OFFSET /* currently a no-op */
}
andi r2, r2, ~_TIF_SINGLESTEP
sw r1, r2
/* Issue a sigtrap */
{
lw r0, r0 /* indirect thru thread_info to get task_info*/
addi r1, sp, C_ABI_SAVE_AREA_SIZE /* put ptregs pointer into r1 */
move r2, zero /* load error code into r2 */
}
jal send_sigtrap /* issue a SIGTRAP */
FEEDBACK_REENTER(handle_ill)
j .Lresume_userspace /* jump into middle of interrupt_return */
.Ldispatch_normal_ill:
{
jalr r0
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
}
FEEDBACK_REENTER(handle_ill)
{
movei r30, 0 /* not an NMI */
j interrupt_return
}
STD_ENDPROC(handle_ill)
/* Various stub interrupt handlers and syscall handlers */
STD_ENTRY_LOCAL(_kernel_double_fault)
mfspr r1, SPR_EX_CONTEXT_K_0
move r2, lr
move r3, sp
move r4, r52
addi sp, sp, -C_ABI_SAVE_AREA_SIZE
j kernel_double_fault
STD_ENDPROC(_kernel_double_fault)
STD_ENTRY_LOCAL(bad_intr)
mfspr r2, SPR_EX_CONTEXT_K_0
panic "Unhandled interrupt %#x: PC %#lx"
STD_ENDPROC(bad_intr)
/* Put address of pt_regs in reg and jump. */
#define PTREGS_SYSCALL(x, reg) \
STD_ENTRY(_##x); \
{ \
PTREGS_PTR(reg, PTREGS_OFFSET_BASE); \
j x \
}; \
STD_ENDPROC(_##x)
/*
* Special-case sigreturn to not write r0 to the stack on return.
* This is technically more efficient, but it also avoids difficulties
* in the 64-bit OS when handling 32-bit compat code, since we must not
* sign-extend r0 for the sigreturn return-value case.
*/
#define PTREGS_SYSCALL_SIGRETURN(x, reg) \
STD_ENTRY(_##x); \
addli lr, lr, .Lsyscall_sigreturn_skip - .Lhandle_syscall_link; \
{ \
PTREGS_PTR(reg, PTREGS_OFFSET_BASE); \
j x \
}; \
STD_ENDPROC(_##x)
PTREGS_SYSCALL(sys_execve, r3)
PTREGS_SYSCALL(sys_sigaltstack, r2)
PTREGS_SYSCALL_SIGRETURN(sys_rt_sigreturn, r0)
PTREGS_SYSCALL(sys_cmpxchg_badaddr, r1)
/* Save additional callee-saves to pt_regs, put address in r4 and jump. */
STD_ENTRY(_sys_clone)
push_extra_callee_saves r4
j sys_clone
STD_ENDPROC(_sys_clone)
/*
* This entrypoint is taken for the cmpxchg and atomic_update fast
* swints. We may wish to generalize it to other fast swints at some
* point, but for now there are just two very similar ones, which
* makes it faster.
*
* The fast swint code is designed to have a small footprint. It does
* not save or restore any GPRs, counting on the caller-save registers
* to be available to it on entry. It does not modify any callee-save
* registers (including "lr"). It does not check what PL it is being
* called at, so you'd better not call it other than at PL0.
* The <atomic.h> wrapper assumes it only clobbers r20-r29, so if
* it ever is necessary to use more registers, be aware.
*
* It does not use the stack, but since it might be re-interrupted by
* a page fault which would assume the stack was valid, it does
* save/restore the stack pointer and zero it out to make sure it gets reset.
* Since we always keep interrupts disabled, the hypervisor won't
* clobber our EX_CONTEXT_K_x registers, so we don't save/restore them
* (other than to advance the PC on return).
*
* We have to manually validate the user vs kernel address range
* (since at PL1 we can read/write both), and for performance reasons
* we don't allow cmpxchg on the fc000000 memory region, since we only
* validate that the user address is below PAGE_OFFSET.
*
* We place it in the __HEAD section to ensure it is relatively
* near to the intvec_SWINT_1 code (reachable by a conditional branch).
*
* Our use of ATOMIC_LOCK_REG here must match do_page_fault_ics().
*
* As we do in lib/atomic_asm_32.S, we bypass a store if the value we
* would store is the same as the value we just loaded.
*/
__HEAD
.align 64
/* Align much later jump on the start of a cache line. */
#if !ATOMIC_LOCKS_FOUND_VIA_TABLE()
nop
#if PAGE_SIZE >= 0x10000
nop
#endif
#endif
ENTRY(sys_cmpxchg)
/*
* Save "sp" and set it zero for any possible page fault.
*
* HACK: We want to both zero sp and check r0's alignment,
* so we do both at once. If "sp" becomes nonzero we
* know r0 is unaligned and branch to the error handler that
* restores sp, so this is OK.
*
* ICS is disabled right now so having a garbage but nonzero
* sp is OK, since we won't execute any faulting instructions
* when it is nonzero.
*/
{
move r27, sp
andi sp, r0, 3
}
/*
* Get the lock address in ATOMIC_LOCK_REG, and also validate that the
* address is less than PAGE_OFFSET, since that won't trap at PL1.
* We only use bits less than PAGE_SHIFT to avoid having to worry
* about aliasing among multiple mappings of the same physical page,
* and we ignore the low 3 bits so we have one lock that covers
* both a cmpxchg64() and a cmpxchg() on either its low or high word.
* NOTE: this must match __atomic_hashed_lock() in lib/atomic_32.c.
*/
#if (PAGE_OFFSET & 0xffff) != 0
# error Code here assumes PAGE_OFFSET can be loaded with just hi16()
#endif
#if ATOMIC_LOCKS_FOUND_VIA_TABLE()
{
/* Check for unaligned input. */
bnz sp, .Lcmpxchg_badaddr
mm r25, r0, zero, 3, PAGE_SHIFT-1
}
{
crc32_32 r25, zero, r25
moveli r21, lo16(atomic_lock_ptr)
}
{
auli r21, r21, ha16(atomic_lock_ptr)
auli r23, zero, hi16(PAGE_OFFSET) /* hugepage-aligned */
}
{
shri r20, r25, 32 - ATOMIC_HASH_L1_SHIFT
slt_u r23, r0, r23
lw r26, r0 /* see comment in the "#else" for the "lw r26". */
}
{
s2a r21, r20, r21
bbns r23, .Lcmpxchg_badaddr
}
{
lw r21, r21
seqi r23, TREG_SYSCALL_NR_NAME, __NR_FAST_cmpxchg64
andi r25, r25, ATOMIC_HASH_L2_SIZE - 1
}
{
/* Branch away at this point if we're doing a 64-bit cmpxchg. */
bbs r23, .Lcmpxchg64
andi r23, r0, 7 /* Precompute alignment for cmpxchg64. */
}
{
s2a ATOMIC_LOCK_REG_NAME, r25, r21
j .Lcmpxchg32_tns /* see comment in the #else for the jump. */
}
#else /* ATOMIC_LOCKS_FOUND_VIA_TABLE() */
{
/* Check for unaligned input. */
bnz sp, .Lcmpxchg_badaddr
auli r23, zero, hi16(PAGE_OFFSET) /* hugepage-aligned */
}
{
/*
* Slide bits into position for 'mm'. We want to ignore
* the low 3 bits of r0, and consider only the next
* ATOMIC_HASH_SHIFT bits.
* Because of C pointer arithmetic, we want to compute this:
*
* ((char*)atomic_locks +
* (((r0 >> 3) & (1 << (ATOMIC_HASH_SIZE - 1))) << 2))
*
* Instead of two shifts we just ">> 1", and use 'mm'
* to ignore the low and high bits we don't want.
*/
shri r25, r0, 1
slt_u r23, r0, r23
/*
* Ensure that the TLB is loaded before we take out the lock.
* On tilepro, this will start fetching the value all the way
* into our L1 as well (and if it gets modified before we
* grab the lock, it will be invalidated from our cache
* before we reload it). On tile64, we'll start fetching it
* into our L1 if we're the home, and if we're not, we'll
* still at least start fetching it into the home's L2.
*/
lw r26, r0
}
{
auli r21, zero, ha16(atomic_locks)
bbns r23, .Lcmpxchg_badaddr
}
#if PAGE_SIZE < 0x10000
/* atomic_locks is page-aligned so for big pages we don't need this. */
addli r21, r21, lo16(atomic_locks)
#endif
{
/*
* Insert the hash bits into the page-aligned pointer.
* ATOMIC_HASH_SHIFT is so big that we don't actually hash
* the unmasked address bits, as that may cause unnecessary
* collisions.
*/
mm ATOMIC_LOCK_REG_NAME, r25, r21, 2, (ATOMIC_HASH_SHIFT + 2) - 1
seqi r23, TREG_SYSCALL_NR_NAME, __NR_FAST_cmpxchg64
}
{
/* Branch away at this point if we're doing a 64-bit cmpxchg. */
bbs r23, .Lcmpxchg64
andi r23, r0, 7 /* Precompute alignment for cmpxchg64. */
}
{
/*
* We very carefully align the code that actually runs with
* the lock held (twelve bundles) so that we know it is all in
* the icache when we start. This instruction (the jump) is
* at the start of the first cache line, address zero mod 64;
* we jump to the very end of the second cache line to get that
* line loaded in the icache, then fall through to issue the tns
* in the third cache line, at which point it's all cached.
* Note that is for performance, not correctness.
*/
j .Lcmpxchg32_tns
}
#endif /* ATOMIC_LOCKS_FOUND_VIA_TABLE() */
/* Symbol for do_page_fault_ics() to use to compare against the PC. */
.global __sys_cmpxchg_grab_lock
__sys_cmpxchg_grab_lock:
/*
* Perform the actual cmpxchg or atomic_update.
*/
.Ldo_cmpxchg32:
{
lw r21, r0
seqi r23, TREG_SYSCALL_NR_NAME, __NR_FAST_atomic_update
move r24, r2
}
{
seq r22, r21, r1 /* See if cmpxchg matches. */
and r25, r21, r1 /* If atomic_update, compute (*mem & mask) */
}
{
or r22, r22, r23 /* Skip compare branch for atomic_update. */
add r25, r25, r2 /* Compute (*mem & mask) + addend. */
}
{
mvnz r24, r23, r25 /* Use atomic_update value if appropriate. */
bbns r22, .Lcmpxchg32_nostore
}
seq r22, r24, r21 /* Are we storing the value we loaded? */
bbs r22, .Lcmpxchg32_nostore
sw r0, r24
/* The following instruction is the start of the second cache line. */
/* Do slow mtspr here so the following "mf" waits less. */
{
move sp, r27
mtspr SPR_EX_CONTEXT_K_0, r28
}
mf
{
move r0, r21
sw ATOMIC_LOCK_REG_NAME, zero
}
iret
/* Duplicated code here in the case where we don't overlap "mf" */
.Lcmpxchg32_nostore:
{
move r0, r21
sw ATOMIC_LOCK_REG_NAME, zero
}
{
move sp, r27
mtspr SPR_EX_CONTEXT_K_0, r28
}
iret
/*
* The locking code is the same for 32-bit cmpxchg/atomic_update,
* and for 64-bit cmpxchg. We provide it as a macro and put
* it into both versions. We can't share the code literally
* since it depends on having the right branch-back address.
*/
.macro cmpxchg_lock, bitwidth
/* Lock; if we succeed, jump back up to the read-modify-write. */
#ifdef CONFIG_SMP
tns r21, ATOMIC_LOCK_REG_NAME
#else
/*
* Non-SMP preserves all the lock infrastructure, to keep the
* code simpler for the interesting (SMP) case. However, we do
* one small optimization here and in atomic_asm.S, which is
* to fake out acquiring the actual lock in the atomic_lock table.
*/
movei r21, 0
#endif
/* Issue the slow SPR here while the tns result is in flight. */
mfspr r28, SPR_EX_CONTEXT_K_0
{
addi r28, r28, 8 /* return to the instruction after the swint1 */
bzt r21, .Ldo_cmpxchg\bitwidth
}
/*
* The preceding instruction is the last thing that must be
* hot in the icache before we do the "tns" above.
*/
#ifdef CONFIG_SMP
/*
* We failed to acquire the tns lock on our first try. Now use
* bounded exponential backoff to retry, like __atomic_spinlock().
*/
{
moveli r23, 2048 /* maximum backoff time in cycles */
moveli r25, 32 /* starting backoff time in cycles */
}
1: mfspr r26, CYCLE_LOW /* get start point for this backoff */
2: mfspr r22, CYCLE_LOW /* test to see if we've backed off enough */
sub r22, r22, r26
slt r22, r22, r25
bbst r22, 2b
{
shli r25, r25, 1 /* double the backoff; retry the tns */
tns r21, ATOMIC_LOCK_REG_NAME
}
slt r26, r23, r25 /* is the proposed backoff too big? */
{
mvnz r25, r26, r23
bzt r21, .Ldo_cmpxchg\bitwidth
}
j 1b
#endif /* CONFIG_SMP */
.endm
.Lcmpxchg32_tns:
/*
* This is the last instruction on the second cache line.
* The nop here loads the second line, then we fall through
* to the tns to load the third line before we take the lock.
*/
nop
cmpxchg_lock 32
/*
* This code is invoked from sys_cmpxchg after most of the
* preconditions have been checked. We still need to check
* that r0 is 8-byte aligned, since if it's not we won't
* actually be atomic. However, ATOMIC_LOCK_REG has the atomic
* lock pointer and r27/r28 have the saved SP/PC.
* r23 is holding "r0 & 7" so we can test for alignment.
* The compare value is in r2/r3; the new value is in r4/r5.
* On return, we must put the old value in r0/r1.
*/
.align 64
.Lcmpxchg64:
{
#if ATOMIC_LOCKS_FOUND_VIA_TABLE()
s2a ATOMIC_LOCK_REG_NAME, r25, r21
#endif
bzt r23, .Lcmpxchg64_tns
}
j .Lcmpxchg_badaddr
.Ldo_cmpxchg64:
{
lw r21, r0
addi r25, r0, 4
}
{
lw r1, r25
}
seq r26, r21, r2
{
bz r26, .Lcmpxchg64_mismatch
seq r26, r1, r3
}
{
bz r26, .Lcmpxchg64_mismatch
}
sw r0, r4
sw r25, r5
/*
* The 32-bit path provides optimized "match" and "mismatch"
* iret paths, but we don't have enough bundles in this cache line
* to do that, so we just make even the "mismatch" path do an "mf".
*/
.Lcmpxchg64_mismatch:
{
move sp, r27
mtspr SPR_EX_CONTEXT_K_0, r28
}
mf
{
move r0, r21
sw ATOMIC_LOCK_REG_NAME, zero
}
iret
.Lcmpxchg64_tns:
cmpxchg_lock 64
/*
* Reset sp and revector to sys_cmpxchg_badaddr(), which will
* just raise the appropriate signal and exit. Doing it this
* way means we don't have to duplicate the code in intvec.S's
* int_hand macro that locates the top of the stack.
*/
.Lcmpxchg_badaddr:
{
moveli TREG_SYSCALL_NR_NAME, __NR_cmpxchg_badaddr
move sp, r27
}
j intvec_SWINT_1
ENDPROC(sys_cmpxchg)
ENTRY(__sys_cmpxchg_end)
/* The single-step support may need to read all the registers. */
int_unalign:
push_extra_callee_saves r0
j do_trap
/* Include .intrpt1 array of interrupt vectors */
.section ".intrpt1", "ax"
#define op_handle_perf_interrupt bad_intr
#define op_handle_aux_perf_interrupt bad_intr
#ifndef CONFIG_HARDWALL
#define do_hardwall_trap bad_intr
#endif
int_hand INT_ITLB_MISS, ITLB_MISS, \
do_page_fault, handle_interrupt_no_single_step
int_hand INT_MEM_ERROR, MEM_ERROR, bad_intr
int_hand INT_ILL, ILL, do_trap, handle_ill
int_hand INT_GPV, GPV, do_trap
int_hand INT_SN_ACCESS, SN_ACCESS, do_trap
int_hand INT_IDN_ACCESS, IDN_ACCESS, do_trap
int_hand INT_UDN_ACCESS, UDN_ACCESS, do_trap
int_hand INT_IDN_REFILL, IDN_REFILL, bad_intr
int_hand INT_UDN_REFILL, UDN_REFILL, bad_intr
int_hand INT_IDN_COMPLETE, IDN_COMPLETE, bad_intr
int_hand INT_UDN_COMPLETE, UDN_COMPLETE, bad_intr
int_hand INT_SWINT_3, SWINT_3, do_trap
int_hand INT_SWINT_2, SWINT_2, do_trap
int_hand INT_SWINT_1, SWINT_1, SYSCALL, handle_syscall
int_hand INT_SWINT_0, SWINT_0, do_trap
int_hand INT_UNALIGN_DATA, UNALIGN_DATA, int_unalign
int_hand INT_DTLB_MISS, DTLB_MISS, do_page_fault
int_hand INT_DTLB_ACCESS, DTLB_ACCESS, do_page_fault
int_hand INT_DMATLB_MISS, DMATLB_MISS, do_page_fault
int_hand INT_DMATLB_ACCESS, DMATLB_ACCESS, do_page_fault
int_hand INT_SNITLB_MISS, SNITLB_MISS, do_page_fault
int_hand INT_SN_NOTIFY, SN_NOTIFY, bad_intr
int_hand INT_SN_FIREWALL, SN_FIREWALL, do_hardwall_trap
int_hand INT_IDN_FIREWALL, IDN_FIREWALL, bad_intr
int_hand INT_UDN_FIREWALL, UDN_FIREWALL, do_hardwall_trap
int_hand INT_TILE_TIMER, TILE_TIMER, do_timer_interrupt
int_hand INT_IDN_TIMER, IDN_TIMER, bad_intr
int_hand INT_UDN_TIMER, UDN_TIMER, bad_intr
int_hand INT_DMA_NOTIFY, DMA_NOTIFY, bad_intr
int_hand INT_IDN_CA, IDN_CA, bad_intr
int_hand INT_UDN_CA, UDN_CA, bad_intr
int_hand INT_IDN_AVAIL, IDN_AVAIL, bad_intr
int_hand INT_UDN_AVAIL, UDN_AVAIL, bad_intr
int_hand INT_PERF_COUNT, PERF_COUNT, \
op_handle_perf_interrupt, handle_nmi
int_hand INT_INTCTRL_3, INTCTRL_3, bad_intr
#if CONFIG_KERNEL_PL == 2
dc_dispatch INT_INTCTRL_2, INTCTRL_2
int_hand INT_INTCTRL_1, INTCTRL_1, bad_intr
#else
int_hand INT_INTCTRL_2, INTCTRL_2, bad_intr
dc_dispatch INT_INTCTRL_1, INTCTRL_1
#endif
int_hand INT_INTCTRL_0, INTCTRL_0, bad_intr
int_hand INT_MESSAGE_RCV_DWNCL, MESSAGE_RCV_DWNCL, \
hv_message_intr
int_hand INT_DEV_INTR_DWNCL, DEV_INTR_DWNCL, \
tile_dev_intr
int_hand INT_I_ASID, I_ASID, bad_intr
int_hand INT_D_ASID, D_ASID, bad_intr
int_hand INT_DMATLB_MISS_DWNCL, DMATLB_MISS_DWNCL, \
do_page_fault
int_hand INT_SNITLB_MISS_DWNCL, SNITLB_MISS_DWNCL, \
do_page_fault
int_hand INT_DMATLB_ACCESS_DWNCL, DMATLB_ACCESS_DWNCL, \
do_page_fault
int_hand INT_SN_CPL, SN_CPL, bad_intr
int_hand INT_DOUBLE_FAULT, DOUBLE_FAULT, do_trap
#if CHIP_HAS_AUX_PERF_COUNTERS()
int_hand INT_AUX_PERF_COUNT, AUX_PERF_COUNT, \
op_handle_aux_perf_interrupt, handle_nmi
#endif
/* Synthetic interrupt delivered only by the simulator */
int_hand INT_BREAKPOINT, BREAKPOINT, do_breakpoint
View Git Blame Copy Permalink