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commit 68fb3ca0e408e00db1c3f8fccdfa19e274c033be upstream. We've had issues with gcc and 'asm goto' before, and we created a 'asm_volatile_goto()' macro for that in the past: see commits3f0116c323("compiler/gcc4: Add quirk for 'asm goto' miscompilation bug") anda9f180345f("compiler/gcc4: Make quirk for asm_volatile_goto() unconditional"). Then, much later, we ended up removing the workaround in commit43c249ea0b("compiler-gcc.h: remove ancient workaround for gcc PR 58670") because we no longer supported building the kernel with the affected gcc versions, but we left the macro uses around. Now, Sean Christopherson reports a new version of a very similar problem, which is fixed by re-applying that ancient workaround. But the problem in question is limited to only the 'asm goto with outputs' cases, so instead of re-introducing the old workaround as-is, let's rename and limit the workaround to just that much less common case. It looks like there are at least two separate issues that all hit in this area: (a) some versions of gcc don't mark the asm goto as 'volatile' when it has outputs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98619 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110420 which is easy to work around by just adding the 'volatile' by hand. (b) Internal compiler errors: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110422 which are worked around by adding the extra empty 'asm' as a barrier, as in the original workaround. but the problem Sean sees may be a third thing since it involves bad code generation (not an ICE) even with the manually added 'volatile'. The same old workaround works for this case, even if this feels a bit like voodoo programming and may only be hiding the issue. Reported-and-tested-by: Sean Christopherson <seanjc@google.com> Link: https://lore.kernel.org/all/20240208220604.140859-1-seanjc@google.com/ Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Uros Bizjak <ubizjak@gmail.com> Cc: Jakub Jelinek <jakub@redhat.com> Cc: Andrew Pinski <quic_apinski@quicinc.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
176 lines
4.2 KiB
C
176 lines
4.2 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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#include <asm/extable.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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.macro EMIT_WARN_ENTRY addr,file,line,flags
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EX_TABLE(\addr,\addr+4)
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__EMIT_BUG_ENTRY \addr,\file,\line,\flags
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.endm
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.macro EMIT_BUG_ENTRY addr,file,line,flags
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.if \flags & 1 /* BUGFLAG_WARNING */
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.err /* Use EMIT_WARN_ENTRY for warnings */
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.endif
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__EMIT_BUG_ENTRY \addr,\file,\line,\flags
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.endm
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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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#define WARN_ENTRY(insn, flags, label, ...) \
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asm goto( \
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"1: " insn "\n" \
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EX_TABLE(1b, %l[label]) \
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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__ : : label)
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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) do { \
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__label__ __label_warn_on; \
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\
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WARN_ENTRY("twi 31, 0, 0", BUGFLAG_WARNING | (flags), __label_warn_on); \
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unreachable(); \
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\
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__label_warn_on: \
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break; \
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} while (0)
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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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bool __ret_warn_on = false; \
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do { \
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if (__builtin_constant_p((x))) { \
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if (!(x)) \
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break; \
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__WARN(); \
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__ret_warn_on = true; \
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} else { \
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__label__ __label_warn_on; \
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\
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WARN_ENTRY(PPC_TLNEI " %4, 0", \
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BUGFLAG_WARNING | BUGFLAG_TAINT(TAINT_WARN), \
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__label_warn_on, \
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"r" ((__force long)(x))); \
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break; \
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__label_warn_on: \
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__ret_warn_on = true; \
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} \
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} while (0); \
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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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.macro EMIT_WARN_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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#define _EMIT_WARN_ENTRY
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#endif
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#endif /* CONFIG_BUG */
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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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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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