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linux/arch/powerpc/kernel/ptrace/ptrace-adv.c
Nicholas Piggin 59dc5bfca0 powerpc/64s: avoid reloading (H)SRR registers if they are still valid 
When an interrupt is taken, the SRR registers are set to return to where
it left off. Unless they are modified in the meantime, or the return
address or MSR are modified, there is no need to reload these registers
when returning from interrupt.

Introduce per-CPU flags that track the validity of SRR and HSRR
registers. These are cleared when returning from interrupt, when
using the registers for something else (e.g., OPAL calls), when
adjusting the return address or MSR of a context, and when context
switching (which changes the return address and MSR).

This improves the performance of interrupt returns.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fold in fixup patch from Nick]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210617155116.2167984-5-npiggin@gmail.com
2021-06-25 00:06:55 +10:00

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// SPDX-License-Identifier: GPL-2.0-or-later
#include <linux/regset.h>
#include <linux/hw_breakpoint.h>
#include "ptrace-decl.h"
void user_enable_single_step(struct task_struct *task)
{
struct pt_regs *regs = task->thread.regs;
if (regs != NULL) {
task->thread.debug.dbcr0 &= ~DBCR0_BT;
task->thread.debug.dbcr0 |= DBCR0_IDM | DBCR0_IC;
regs_set_return_msr(regs, regs->msr | MSR_DE);
}
set_tsk_thread_flag(task, TIF_SINGLESTEP);
}
void user_enable_block_step(struct task_struct *task)
{
struct pt_regs *regs = task->thread.regs;
if (regs != NULL) {
task->thread.debug.dbcr0 &= ~DBCR0_IC;
task->thread.debug.dbcr0 = DBCR0_IDM | DBCR0_BT;
regs_set_return_msr(regs, regs->msr | MSR_DE);
}
set_tsk_thread_flag(task, TIF_SINGLESTEP);
}
void user_disable_single_step(struct task_struct *task)
{
struct pt_regs *regs = task->thread.regs;
if (regs != NULL) {
/*
* The logic to disable single stepping should be as
* simple as turning off the Instruction Complete flag.
* And, after doing so, if all debug flags are off, turn
* off DBCR0(IDM) and MSR(DE) .... Torez
*/
task->thread.debug.dbcr0 &= ~(DBCR0_IC | DBCR0_BT);
/*
* Test to see if any of the DBCR_ACTIVE_EVENTS bits are set.
*/
if (!DBCR_ACTIVE_EVENTS(task->thread.debug.dbcr0,
task->thread.debug.dbcr1)) {
/*
* All debug events were off.....
*/
task->thread.debug.dbcr0 &= ~DBCR0_IDM;
regs_set_return_msr(regs, regs->msr & ~MSR_DE);
}
}
clear_tsk_thread_flag(task, TIF_SINGLESTEP);
}
void ppc_gethwdinfo(struct ppc_debug_info *dbginfo)
{
dbginfo->version = 1;
dbginfo->num_instruction_bps = CONFIG_PPC_ADV_DEBUG_IACS;
dbginfo->num_data_bps = CONFIG_PPC_ADV_DEBUG_DACS;
dbginfo->num_condition_regs = CONFIG_PPC_ADV_DEBUG_DVCS;
dbginfo->data_bp_alignment = 4;
dbginfo->sizeof_condition = 4;
dbginfo->features = PPC_DEBUG_FEATURE_INSN_BP_RANGE |
PPC_DEBUG_FEATURE_INSN_BP_MASK;
if (IS_ENABLED(CONFIG_PPC_ADV_DEBUG_DAC_RANGE))
dbginfo->features |= PPC_DEBUG_FEATURE_DATA_BP_RANGE |
PPC_DEBUG_FEATURE_DATA_BP_MASK;
}
int ptrace_get_debugreg(struct task_struct *child, unsigned long addr,
unsigned long __user *datalp)
{
/* We only support one DABR and no IABRS at the moment */
if (addr > 0)
return -EINVAL;
return put_user(child->thread.debug.dac1, datalp);
}
int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, unsigned long data)
{
struct pt_regs *regs = task->thread.regs;
#ifdef CONFIG_HAVE_HW_BREAKPOINT
int ret;
struct thread_struct *thread = &task->thread;
struct perf_event *bp;
struct perf_event_attr attr;
#endif /* CONFIG_HAVE_HW_BREAKPOINT */
/* For ppc64 we support one DABR and no IABR's at the moment (ppc64).
* For embedded processors we support one DAC and no IAC's at the
* moment.
*/
if (addr > 0)
return -EINVAL;
/* The bottom 3 bits in dabr are flags */
if ((data & ~0x7UL) >= TASK_SIZE)
return -EIO;
/* As described above, it was assumed 3 bits were passed with the data
* address, but we will assume only the mode bits will be passed
* as to not cause alignment restrictions for DAC-based processors.
*/
/* DAC's hold the whole address without any mode flags */
task->thread.debug.dac1 = data & ~0x3UL;
if (task->thread.debug.dac1 == 0) {
dbcr_dac(task) &= ~(DBCR_DAC1R | DBCR_DAC1W);
if (!DBCR_ACTIVE_EVENTS(task->thread.debug.dbcr0,
task->thread.debug.dbcr1)) {
regs_set_return_msr(regs, regs->msr & ~MSR_DE);
task->thread.debug.dbcr0 &= ~DBCR0_IDM;
}
return 0;
}
/* Read or Write bits must be set */
if (!(data & 0x3UL))
return -EINVAL;
/* Set the Internal Debugging flag (IDM bit 1) for the DBCR0 register */
task->thread.debug.dbcr0 |= DBCR0_IDM;
/* Check for write and read flags and set DBCR0 accordingly */
dbcr_dac(task) &= ~(DBCR_DAC1R | DBCR_DAC1W);
if (data & 0x1UL)
dbcr_dac(task) |= DBCR_DAC1R;
if (data & 0x2UL)
dbcr_dac(task) |= DBCR_DAC1W;
regs_set_return_msr(regs, regs->msr | MSR_DE);
return 0;
}
static long set_instruction_bp(struct task_struct *child,
struct ppc_hw_breakpoint *bp_info)
{
int slot;
int slot1_in_use = ((child->thread.debug.dbcr0 & DBCR0_IAC1) != 0);
int slot2_in_use = ((child->thread.debug.dbcr0 & DBCR0_IAC2) != 0);
int slot3_in_use = ((child->thread.debug.dbcr0 & DBCR0_IAC3) != 0);
int slot4_in_use = ((child->thread.debug.dbcr0 & DBCR0_IAC4) != 0);
if (dbcr_iac_range(child) & DBCR_IAC12MODE)
slot2_in_use = 1;
if (dbcr_iac_range(child) & DBCR_IAC34MODE)
slot4_in_use = 1;
if (bp_info->addr >= TASK_SIZE)
return -EIO;
if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT) {
/* Make sure range is valid. */
if (bp_info->addr2 >= TASK_SIZE)
return -EIO;
/* We need a pair of IAC regsisters */
if (!slot1_in_use && !slot2_in_use) {
slot = 1;
child->thread.debug.iac1 = bp_info->addr;
child->thread.debug.iac2 = bp_info->addr2;
child->thread.debug.dbcr0 |= DBCR0_IAC1;
if (bp_info->addr_mode ==
PPC_BREAKPOINT_MODE_RANGE_EXCLUSIVE)
dbcr_iac_range(child) |= DBCR_IAC12X;
else
dbcr_iac_range(child) |= DBCR_IAC12I;
#if CONFIG_PPC_ADV_DEBUG_IACS > 2
} else if ((!slot3_in_use) && (!slot4_in_use)) {
slot = 3;
child->thread.debug.iac3 = bp_info->addr;
child->thread.debug.iac4 = bp_info->addr2;
child->thread.debug.dbcr0 |= DBCR0_IAC3;
if (bp_info->addr_mode ==
PPC_BREAKPOINT_MODE_RANGE_EXCLUSIVE)
dbcr_iac_range(child) |= DBCR_IAC34X;
else
dbcr_iac_range(child) |= DBCR_IAC34I;
#endif
} else {
return -ENOSPC;
}
} else {
/* We only need one. If possible leave a pair free in
* case a range is needed later
*/
if (!slot1_in_use) {
/*
* Don't use iac1 if iac1-iac2 are free and either
* iac3 or iac4 (but not both) are free
*/
if (slot2_in_use || slot3_in_use == slot4_in_use) {
slot = 1;
child->thread.debug.iac1 = bp_info->addr;
child->thread.debug.dbcr0 |= DBCR0_IAC1;
goto out;
}
}
if (!slot2_in_use) {
slot = 2;
child->thread.debug.iac2 = bp_info->addr;
child->thread.debug.dbcr0 |= DBCR0_IAC2;
#if CONFIG_PPC_ADV_DEBUG_IACS > 2
} else if (!slot3_in_use) {
slot = 3;
child->thread.debug.iac3 = bp_info->addr;
child->thread.debug.dbcr0 |= DBCR0_IAC3;
} else if (!slot4_in_use) {
slot = 4;
child->thread.debug.iac4 = bp_info->addr;
child->thread.debug.dbcr0 |= DBCR0_IAC4;
#endif
} else {
return -ENOSPC;
}
}
out:
child->thread.debug.dbcr0 |= DBCR0_IDM;
regs_set_return_msr(child->thread.regs, child->thread.regs->msr | MSR_DE);
return slot;
}
static int del_instruction_bp(struct task_struct *child, int slot)
{
switch (slot) {
case 1:
if ((child->thread.debug.dbcr0 & DBCR0_IAC1) == 0)
return -ENOENT;
if (dbcr_iac_range(child) & DBCR_IAC12MODE) {
/* address range - clear slots 1 & 2 */
child->thread.debug.iac2 = 0;
dbcr_iac_range(child) &= ~DBCR_IAC12MODE;
}
child->thread.debug.iac1 = 0;
child->thread.debug.dbcr0 &= ~DBCR0_IAC1;
break;
case 2:
if ((child->thread.debug.dbcr0 & DBCR0_IAC2) == 0)
return -ENOENT;
if (dbcr_iac_range(child) & DBCR_IAC12MODE)
/* used in a range */
return -EINVAL;
child->thread.debug.iac2 = 0;
child->thread.debug.dbcr0 &= ~DBCR0_IAC2;
break;
#if CONFIG_PPC_ADV_DEBUG_IACS > 2
case 3:
if ((child->thread.debug.dbcr0 & DBCR0_IAC3) == 0)
return -ENOENT;
if (dbcr_iac_range(child) & DBCR_IAC34MODE) {
/* address range - clear slots 3 & 4 */
child->thread.debug.iac4 = 0;
dbcr_iac_range(child) &= ~DBCR_IAC34MODE;
}
child->thread.debug.iac3 = 0;
child->thread.debug.dbcr0 &= ~DBCR0_IAC3;
break;
case 4:
if ((child->thread.debug.dbcr0 & DBCR0_IAC4) == 0)
return -ENOENT;
if (dbcr_iac_range(child) & DBCR_IAC34MODE)
/* Used in a range */
return -EINVAL;
child->thread.debug.iac4 = 0;
child->thread.debug.dbcr0 &= ~DBCR0_IAC4;
break;
#endif
default:
return -EINVAL;
}
return 0;
}
static int set_dac(struct task_struct *child, struct ppc_hw_breakpoint *bp_info)
{
int byte_enable =
(bp_info->condition_mode >> PPC_BREAKPOINT_CONDITION_BE_SHIFT)
& 0xf;
int condition_mode =
bp_info->condition_mode & PPC_BREAKPOINT_CONDITION_MODE;
int slot;
if (byte_enable && condition_mode == 0)
return -EINVAL;
if (bp_info->addr >= TASK_SIZE)
return -EIO;
if ((dbcr_dac(child) & (DBCR_DAC1R | DBCR_DAC1W)) == 0) {
slot = 1;
if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_READ)
dbcr_dac(child) |= DBCR_DAC1R;
if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_WRITE)
dbcr_dac(child) |= DBCR_DAC1W;
child->thread.debug.dac1 = (unsigned long)bp_info->addr;
#if CONFIG_PPC_ADV_DEBUG_DVCS > 0
if (byte_enable) {
child->thread.debug.dvc1 =
(unsigned long)bp_info->condition_value;
child->thread.debug.dbcr2 |=
((byte_enable << DBCR2_DVC1BE_SHIFT) |
(condition_mode << DBCR2_DVC1M_SHIFT));
}
#endif
#ifdef CONFIG_PPC_ADV_DEBUG_DAC_RANGE
} else if (child->thread.debug.dbcr2 & DBCR2_DAC12MODE) {
/* Both dac1 and dac2 are part of a range */
return -ENOSPC;
#endif
} else if ((dbcr_dac(child) & (DBCR_DAC2R | DBCR_DAC2W)) == 0) {
slot = 2;
if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_READ)
dbcr_dac(child) |= DBCR_DAC2R;
if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_WRITE)
dbcr_dac(child) |= DBCR_DAC2W;
child->thread.debug.dac2 = (unsigned long)bp_info->addr;
#if CONFIG_PPC_ADV_DEBUG_DVCS > 0
if (byte_enable) {
child->thread.debug.dvc2 =
(unsigned long)bp_info->condition_value;
child->thread.debug.dbcr2 |=
((byte_enable << DBCR2_DVC2BE_SHIFT) |
(condition_mode << DBCR2_DVC2M_SHIFT));
}
#endif
} else {
return -ENOSPC;
}
child->thread.debug.dbcr0 |= DBCR0_IDM;
regs_set_return_msr(child->thread.regs, child->thread.regs->msr | MSR_DE);
return slot + 4;
}
static int del_dac(struct task_struct *child, int slot)
{
if (slot == 1) {
if ((dbcr_dac(child) & (DBCR_DAC1R | DBCR_DAC1W)) == 0)
return -ENOENT;
child->thread.debug.dac1 = 0;
dbcr_dac(child) &= ~(DBCR_DAC1R | DBCR_DAC1W);
#ifdef CONFIG_PPC_ADV_DEBUG_DAC_RANGE
if (child->thread.debug.dbcr2 & DBCR2_DAC12MODE) {
child->thread.debug.dac2 = 0;
child->thread.debug.dbcr2 &= ~DBCR2_DAC12MODE;
}
child->thread.debug.dbcr2 &= ~(DBCR2_DVC1M | DBCR2_DVC1BE);
#endif
#if CONFIG_PPC_ADV_DEBUG_DVCS > 0
child->thread.debug.dvc1 = 0;
#endif
} else if (slot == 2) {
if ((dbcr_dac(child) & (DBCR_DAC2R | DBCR_DAC2W)) == 0)
return -ENOENT;
#ifdef CONFIG_PPC_ADV_DEBUG_DAC_RANGE
if (child->thread.debug.dbcr2 & DBCR2_DAC12MODE)
/* Part of a range */
return -EINVAL;
child->thread.debug.dbcr2 &= ~(DBCR2_DVC2M | DBCR2_DVC2BE);
#endif
#if CONFIG_PPC_ADV_DEBUG_DVCS > 0
child->thread.debug.dvc2 = 0;
#endif
child->thread.debug.dac2 = 0;
dbcr_dac(child) &= ~(DBCR_DAC2R | DBCR_DAC2W);
} else {
return -EINVAL;
}
return 0;
}
#ifdef CONFIG_PPC_ADV_DEBUG_DAC_RANGE
static int set_dac_range(struct task_struct *child,
struct ppc_hw_breakpoint *bp_info)
{
int mode = bp_info->addr_mode & PPC_BREAKPOINT_MODE_MASK;
/* We don't allow range watchpoints to be used with DVC */
if (bp_info->condition_mode)
return -EINVAL;
/*
* Best effort to verify the address range. The user/supervisor bits
* prevent trapping in kernel space, but let's fail on an obvious bad
* range. The simple test on the mask is not fool-proof, and any
* exclusive range will spill over into kernel space.
*/
if (bp_info->addr >= TASK_SIZE)
return -EIO;
if (mode == PPC_BREAKPOINT_MODE_MASK) {
/*
* dac2 is a bitmask. Don't allow a mask that makes a
* kernel space address from a valid dac1 value
*/
if (~((unsigned long)bp_info->addr2) >= TASK_SIZE)
return -EIO;
} else {
/*
* For range breakpoints, addr2 must also be a valid address
*/
if (bp_info->addr2 >= TASK_SIZE)
return -EIO;
}
if (child->thread.debug.dbcr0 &
(DBCR0_DAC1R | DBCR0_DAC1W | DBCR0_DAC2R | DBCR0_DAC2W))
return -ENOSPC;
if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_READ)
child->thread.debug.dbcr0 |= (DBCR0_DAC1R | DBCR0_IDM);
if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_WRITE)
child->thread.debug.dbcr0 |= (DBCR0_DAC1W | DBCR0_IDM);
child->thread.debug.dac1 = bp_info->addr;
child->thread.debug.dac2 = bp_info->addr2;
if (mode == PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE)
child->thread.debug.dbcr2 |= DBCR2_DAC12M;
else if (mode == PPC_BREAKPOINT_MODE_RANGE_EXCLUSIVE)
child->thread.debug.dbcr2 |= DBCR2_DAC12MX;
else /* PPC_BREAKPOINT_MODE_MASK */
child->thread.debug.dbcr2 |= DBCR2_DAC12MM;
regs_set_return_msr(child->thread.regs, child->thread.regs->msr | MSR_DE);
return 5;
}
#endif /* CONFIG_PPC_ADV_DEBUG_DAC_RANGE */
long ppc_set_hwdebug(struct task_struct *child, struct ppc_hw_breakpoint *bp_info)
{
if (bp_info->version != 1)
return -ENOTSUPP;
/*
* Check for invalid flags and combinations
*/
if (bp_info->trigger_type == 0 ||
(bp_info->trigger_type & ~(PPC_BREAKPOINT_TRIGGER_EXECUTE |
PPC_BREAKPOINT_TRIGGER_RW)) ||
(bp_info->addr_mode & ~PPC_BREAKPOINT_MODE_MASK) ||
(bp_info->condition_mode &
~(PPC_BREAKPOINT_CONDITION_MODE |
PPC_BREAKPOINT_CONDITION_BE_ALL)))
return -EINVAL;
#if CONFIG_PPC_ADV_DEBUG_DVCS == 0
if (bp_info->condition_mode != PPC_BREAKPOINT_CONDITION_NONE)
return -EINVAL;
#endif
if (bp_info->trigger_type & PPC_BREAKPOINT_TRIGGER_EXECUTE) {
if (bp_info->trigger_type != PPC_BREAKPOINT_TRIGGER_EXECUTE ||
bp_info->condition_mode != PPC_BREAKPOINT_CONDITION_NONE)
return -EINVAL;
return set_instruction_bp(child, bp_info);
}
if (bp_info->addr_mode == PPC_BREAKPOINT_MODE_EXACT)
return set_dac(child, bp_info);
#ifdef CONFIG_PPC_ADV_DEBUG_DAC_RANGE
return set_dac_range(child, bp_info);
#else
return -EINVAL;
#endif
}
long ppc_del_hwdebug(struct task_struct *child, long data)
{
int rc;
if (data <= 4)
rc = del_instruction_bp(child, (int)data);
else
rc = del_dac(child, (int)data - 4);
if (!rc) {
if (!DBCR_ACTIVE_EVENTS(child->thread.debug.dbcr0,
child->thread.debug.dbcr1)) {
child->thread.debug.dbcr0 &= ~DBCR0_IDM;
regs_set_return_msr(child->thread.regs,
child->thread.regs->msr & ~MSR_DE);
}
}
return rc;
}
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