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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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325cdacd03
Mike Galbraith reported a situation where a WARN_ON_ONCE() call in DRM code turned into an oops. As it turns out, WARN_ON_ONCE() seems to be completely broken when called from a module. The bug was introduced with the following commit:19d436268d("debug: Add _ONCE() logic to report_bug()") That commit changed WARN_ON_ONCE() to move its 'once' logic into the bug trap handler. It requires a writable bug table so that the BUGFLAG_DONE bit can be written to the flags to indicate the first warning has occurred. The bug table was made writable for vmlinux, which relies on vmlinux.lds.S and vmlinux.lds.h for laying out the sections. However, it wasn't made writable for modules, which rely on the ELF section header flags. Reported-by: Mike Galbraith <efault@gmx.de> Tested-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes:19d436268d("debug: Add _ONCE() logic to report_bug()") Link: http://lkml.kernel.org/r/a53b04235a65478dd9afc51f5b329fdc65c84364.1500095401.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
72 lines
1.5 KiB
C
72 lines
1.5 KiB
C
#ifndef _ASM_S390_BUG_H
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#define _ASM_S390_BUG_H
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#include <linux/kernel.h>
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#ifdef CONFIG_BUG
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#ifdef CONFIG_DEBUG_BUGVERBOSE
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#define __EMIT_BUG(x) do { \
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asm volatile( \
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"0: j 0b+2\n" \
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"1:\n" \
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".section .rodata.str,\"aMS\",@progbits,1\n" \
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"2: .asciz \""__FILE__"\"\n" \
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".previous\n" \
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".section __bug_table,\"aw\"\n" \
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"3: .long 1b-3b,2b-3b\n" \
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" .short %0,%1\n" \
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" .org 3b+%2\n" \
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".previous\n" \
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: : "i" (__LINE__), \
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"i" (x), \
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"i" (sizeof(struct bug_entry))); \
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} while (0)
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#else /* CONFIG_DEBUG_BUGVERBOSE */
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#define __EMIT_BUG(x) do { \
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asm volatile( \
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"0: j 0b+2\n" \
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"1:\n" \
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".section __bug_table,\"aw\"\n" \
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"2: .long 1b-2b\n" \
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" .short %0\n" \
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" .org 2b+%1\n" \
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".previous\n" \
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: : "i" (x), \
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"i" (sizeof(struct bug_entry))); \
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} while (0)
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#endif /* CONFIG_DEBUG_BUGVERBOSE */
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#define BUG() do { \
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__EMIT_BUG(0); \
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unreachable(); \
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} while (0)
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#define __WARN_FLAGS(flags) do { \
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__EMIT_BUG(BUGFLAG_WARNING|(flags)); \
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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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if (unlikely(__ret_warn_on)) \
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__WARN(); \
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} \
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unlikely(__ret_warn_on); \
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})
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#define HAVE_ARCH_BUG
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#define HAVE_ARCH_WARN_ON
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#endif /* CONFIG_BUG */
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#include <asm-generic/bug.h>
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#endif /* _ASM_S390_BUG_H */
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