5222a1d514
On book3s/32 KUAP is performed at segment level. At the moment, when enabling userspace access, only current segment is modified. Then if a write is performed on another user segment, a fault is taken and all other user segments get enabled for userspace access. This then require special attention when disabling userspace access. Having a userspace write access crossing a segment boundary is unlikely. Having a userspace write access crossing a segment boundary back and forth is even more unlikely. So, instead of enabling userspace access on all segments when a write fault occurs, just change which segment has userspace access enabled in order to eliminate the case when more than one segment has userspace access enabled. That simplifies userspace access deactivation. There is however a corner case which is even more unlikely but has to be handled anyway: an unaligned access which is crossing a segment boundary. That would definitely require at least having userspace access enabled on the two segments. To avoid complicating the likely case for a so unlikely happening, handle such situation like an alignment exception and emulate the store. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/8de8580513c1a6e880bad1ba9a69d3efad3d4fa5.1689091022.git.christophe.leroy@csgroup.eu
135 lines
3.2 KiB
C
135 lines
3.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_POWERPC_BUG_H
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#define _ASM_POWERPC_BUG_H
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#ifdef __KERNEL__
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#include <asm/asm-compat.h>
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#ifdef CONFIG_BUG
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#ifdef __ASSEMBLY__
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#include <asm/asm-offsets.h>
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#ifdef CONFIG_DEBUG_BUGVERBOSE
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.macro EMIT_BUG_ENTRY addr,file,line,flags
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.section __bug_table,"aw"
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5001: .4byte \addr - .
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.4byte 5002f - .
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.short \line, \flags
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.org 5001b+BUG_ENTRY_SIZE
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.previous
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.section .rodata,"a"
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5002: .asciz "\file"
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.previous
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.endm
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#else
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.macro EMIT_BUG_ENTRY addr,file,line,flags
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.section __bug_table,"aw"
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5001: .4byte \addr - .
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.short \flags
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.org 5001b+BUG_ENTRY_SIZE
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.previous
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.endm
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#endif /* verbose */
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#else /* !__ASSEMBLY__ */
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/* _EMIT_BUG_ENTRY expects args %0,%1,%2,%3 to be FILE, LINE, flags and
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sizeof(struct bug_entry), respectively */
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#ifdef CONFIG_DEBUG_BUGVERBOSE
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#define _EMIT_BUG_ENTRY \
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".section __bug_table,\"aw\"\n" \
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"2: .4byte 1b - .\n" \
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" .4byte %0 - .\n" \
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" .short %1, %2\n" \
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".org 2b+%3\n" \
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".previous\n"
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#else
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#define _EMIT_BUG_ENTRY \
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".section __bug_table,\"aw\"\n" \
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"2: .4byte 1b - .\n" \
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" .short %2\n" \
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".org 2b+%3\n" \
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".previous\n"
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#endif
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#define BUG_ENTRY(insn, flags, ...) \
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__asm__ __volatile__( \
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"1: " insn "\n" \
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_EMIT_BUG_ENTRY \
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: : "i" (__FILE__), "i" (__LINE__), \
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"i" (flags), \
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"i" (sizeof(struct bug_entry)), \
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##__VA_ARGS__)
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/*
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* BUG_ON() and WARN_ON() do their best to cooperate with compile-time
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* optimisations. However depending on the complexity of the condition
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* some compiler versions may not produce optimal results.
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*/
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#define BUG() do { \
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BUG_ENTRY("twi 31, 0, 0", 0); \
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unreachable(); \
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} while (0)
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#define HAVE_ARCH_BUG
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#define __WARN_FLAGS(flags) BUG_ENTRY("twi 31, 0, 0", BUGFLAG_WARNING | (flags))
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#ifdef CONFIG_PPC64
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#define BUG_ON(x) do { \
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if (__builtin_constant_p(x)) { \
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if (x) \
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BUG(); \
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} else { \
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BUG_ENTRY(PPC_TLNEI " %4, 0", 0, "r" ((__force long)(x))); \
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} \
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} while (0)
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#define WARN_ON(x) ({ \
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int __ret_warn_on = !!(x); \
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if (__builtin_constant_p(__ret_warn_on)) { \
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if (__ret_warn_on) \
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__WARN(); \
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} else { \
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BUG_ENTRY(PPC_TLNEI " %4, 0", \
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BUGFLAG_WARNING | BUGFLAG_TAINT(TAINT_WARN), \
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"r" (__ret_warn_on)); \
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} \
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unlikely(__ret_warn_on); \
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})
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#define HAVE_ARCH_BUG_ON
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#define HAVE_ARCH_WARN_ON
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#endif
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#endif /* __ASSEMBLY __ */
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#else
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#ifdef __ASSEMBLY__
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.macro EMIT_BUG_ENTRY addr,file,line,flags
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.endm
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#else /* !__ASSEMBLY__ */
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#define _EMIT_BUG_ENTRY
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#endif
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#endif /* CONFIG_BUG */
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#define EMIT_WARN_ENTRY EMIT_BUG_ENTRY
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#include <asm-generic/bug.h>
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#ifndef __ASSEMBLY__
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struct pt_regs;
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void hash__do_page_fault(struct pt_regs *);
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void bad_page_fault(struct pt_regs *, int);
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void emulate_single_step(struct pt_regs *regs);
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extern void _exception(int, struct pt_regs *, int, unsigned long);
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extern void _exception_pkey(struct pt_regs *, unsigned long, int);
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extern void die(const char *, struct pt_regs *, long);
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void die_mce(const char *str, struct pt_regs *regs, long err);
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extern bool die_will_crash(void);
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extern void panic_flush_kmsg_start(void);
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extern void panic_flush_kmsg_end(void);
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#endif /* !__ASSEMBLY__ */
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_BUG_H */
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