87e040b645
ARM uses its own BUG() handler which makes its output slightly different from other archtectures. One of the problems is that the ARM implementation doesn't report the function with the BUG() in it, but always reports the PC being in __bug(). The generic implementation doesn't have this problem. Currently we get something like: kernel BUG at fs/proc/breakme.c:35! Unable to handle kernel NULL pointer dereference at virtual address 00000000 ... PC is at __bug+0x20/0x2c With this patch it displays: kernel BUG at fs/proc/breakme.c:35! Internal error: Oops - undefined instruction: 0 [#1] PREEMPT SMP ... PC is at write_breakme+0xd0/0x1b4 This implementation uses an undefined instruction to implement BUG, and sets up a bug table containing the relevant information. Many versions of gcc do not support %c properly for ARM (inserting a # when they shouldn't) so we work around this using distasteful macro magic. v1: Initial version to replace existing ARM BUG() implementation with something more similar to other architectures. v2: Add Thumb support, remove backtrace whitespace output changes. Change to use macros instead of requiring the asm %d flag to work (thanks to Dave Martin <dave.martin@linaro.org>) v3: Remove old BUG() implementation in favor of this one. Remove the Backtrace: message (will submit this separately). Use ARM_EXIT_KEEP() so that some architectures can dump exit text at link time thanks to Stephen Boyd <sboyd@codeaurora.org> (although since we always define GENERIC_BUG this might be academic.) Rebase to linux-2.6.git master. v4: Allow BUGS in modules (these were not reported correctly in v3) (thanks to Stephen Boyd <sboyd@codeaurora.org> for suggesting that.) Remove __bug() as this is no longer needed. v5: Add %progbits as the section flags. Signed-off-by: Simon Glass <sjg@chromium.org> Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> Tested-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
62 lines
1.6 KiB
C
62 lines
1.6 KiB
C
#ifndef _ASMARM_BUG_H
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#define _ASMARM_BUG_H
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#ifdef CONFIG_BUG
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/*
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* Use a suitable undefined instruction to use for ARM/Thumb2 bug handling.
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* We need to be careful not to conflict with those used by other modules and
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* the register_undef_hook() system.
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*/
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#ifdef CONFIG_THUMB2_KERNEL
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#define BUG_INSTR_VALUE 0xde02
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#define BUG_INSTR_TYPE ".hword "
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#else
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#define BUG_INSTR_VALUE 0xe7f001f2
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#define BUG_INSTR_TYPE ".word "
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#endif
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#define BUG() _BUG(__FILE__, __LINE__, BUG_INSTR_VALUE)
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#define _BUG(file, line, value) __BUG(file, line, value)
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#ifdef CONFIG_DEBUG_BUGVERBOSE
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/*
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* The extra indirection is to ensure that the __FILE__ string comes through
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* OK. Many version of gcc do not support the asm %c parameter which would be
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* preferable to this unpleasantness. We use mergeable string sections to
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* avoid multiple copies of the string appearing in the kernel image.
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*/
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#define __BUG(__file, __line, __value) \
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do { \
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BUILD_BUG_ON(sizeof(struct bug_entry) != 12); \
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asm volatile("1:\t" BUG_INSTR_TYPE #__value "\n" \
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".pushsection .rodata.str, \"aMS\", %progbits, 1\n" \
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"2:\t.asciz " #__file "\n" \
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".popsection\n" \
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".pushsection __bug_table,\"a\"\n" \
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"3:\t.word 1b, 2b\n" \
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"\t.hword " #__line ", 0\n" \
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".popsection"); \
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unreachable(); \
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} while (0)
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#else /* not CONFIG_DEBUG_BUGVERBOSE */
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#define __BUG(__file, __line, __value) \
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do { \
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asm volatile(BUG_INSTR_TYPE #__value); \
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unreachable(); \
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} while (0)
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#endif /* CONFIG_DEBUG_BUGVERBOSE */
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#define HAVE_ARCH_BUG
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#endif /* CONFIG_BUG */
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#include <asm-generic/bug.h>
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#endif
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