forked from Minki/linux
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>
69 lines
1.8 KiB
C
69 lines
1.8 KiB
C
/*
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* Copyright (C) 2015 ARM Limited
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* Author: Dave Martin <Dave.Martin@arm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef _ARCH_ARM64_ASM_BUG_H
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#define _ARCH_ARM64_ASM_BUG_H
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#include <asm/brk-imm.h>
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#ifdef CONFIG_DEBUG_BUGVERBOSE
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#define _BUGVERBOSE_LOCATION(file, line) __BUGVERBOSE_LOCATION(file, line)
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#define __BUGVERBOSE_LOCATION(file, line) \
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".pushsection .rodata.str,\"aMS\",@progbits,1\n" \
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"2: .string \"" file "\"\n\t" \
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".popsection\n\t" \
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\
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".long 2b - 0b\n\t" \
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".short " #line "\n\t"
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#else
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#define _BUGVERBOSE_LOCATION(file, line)
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#endif
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#ifdef CONFIG_GENERIC_BUG
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#define __BUG_ENTRY(flags) \
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".pushsection __bug_table,\"aw\"\n\t" \
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".align 2\n\t" \
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"0: .long 1f - 0b\n\t" \
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_BUGVERBOSE_LOCATION(__FILE__, __LINE__) \
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".short " #flags "\n\t" \
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".popsection\n" \
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"1: "
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#else
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#define __BUG_ENTRY(flags) ""
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#endif
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#define __BUG_FLAGS(flags) \
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asm volatile ( \
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__BUG_ENTRY(flags) \
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"brk %[imm]" :: [imm] "i" (BUG_BRK_IMM) \
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);
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#define BUG() do { \
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__BUG_FLAGS(0); \
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unreachable(); \
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} while (0)
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#define __WARN_FLAGS(flags) __BUG_FLAGS(BUGFLAG_WARNING|(flags))
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#define HAVE_ARCH_BUG
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#include <asm-generic/bug.h>
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#endif /* ! _ARCH_ARM64_ASM_BUG_H */
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