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linux/arch/arm64/include/asm/bug.h

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arm64/BUG: Use BRK instruction for generic BUG traps Currently, the minimal default BUG() implementation from asm- generic is used for arm64. This patch uses the BRK software breakpoint instruction to generate a trap instead, similarly to most other arches, with the generic BUG code generating the dmesg boilerplate. This allows bug metadata to be moved to a separate table and reduces the amount of inline code at BUG and WARN sites. This also avoids clobbering any registers before they can be dumped. To mitigate the size of the bug table further, this patch makes use of the existing infrastructure for encoding addresses within the bug table as 32-bit offsets instead of absolute pointers. (Note that this limits the kernel size to 2GB.) Traps are registered at arch_initcall time for aarch64, but BUG has minimal real dependencies and it is desirable to be able to generate bug splats as early as possible. This patch redirects all debug exceptions caused by BRK directly to bug_handler() until the full debug exception support has been initialised. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-07-24 15:37:48 +00:00
/*
* Copyright (C) 2015 ARM Limited
* Author: Dave Martin <Dave.Martin@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _ARCH_ARM64_ASM_BUG_H
#define _ARCH_ARM64_ASM_BUG_H
arm64: move brk immediate argument definitions to separate header Instead of reversing the header dependency between asm/bug.h and asm/debug-monitors.h, split off the brk instruction immediate value defines into a new header asm/brk-imm.h, and include it from both. This solves the circular dependency issue that prevents BUG() from being used in some header files, and keeps the definitions together. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-02-23 07:56:45 +00:00
#include <asm/brk-imm.h>
arm64/BUG: Use BRK instruction for generic BUG traps Currently, the minimal default BUG() implementation from asm- generic is used for arm64. This patch uses the BRK software breakpoint instruction to generate a trap instead, similarly to most other arches, with the generic BUG code generating the dmesg boilerplate. This allows bug metadata to be moved to a separate table and reduces the amount of inline code at BUG and WARN sites. This also avoids clobbering any registers before they can be dumped. To mitigate the size of the bug table further, this patch makes use of the existing infrastructure for encoding addresses within the bug table as 32-bit offsets instead of absolute pointers. (Note that this limits the kernel size to 2GB.) Traps are registered at arch_initcall time for aarch64, but BUG has minimal real dependencies and it is desirable to be able to generate bug splats as early as possible. This patch redirects all debug exceptions caused by BRK directly to bug_handler() until the full debug exception support has been initialised. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-07-24 15:37:48 +00:00
#ifdef CONFIG_GENERIC_BUG
#define HAVE_ARCH_BUG
#ifdef CONFIG_DEBUG_BUGVERBOSE
#define _BUGVERBOSE_LOCATION(file, line) __BUGVERBOSE_LOCATION(file, line)
#define __BUGVERBOSE_LOCATION(file, line) \
".pushsection .rodata.str,\"aMS\",@progbits,1\n" \
"2: .string \"" file "\"\n\t" \
".popsection\n\t" \
\
".long 2b - 0b\n\t" \
".short " #line "\n\t"
#else
#define _BUGVERBOSE_LOCATION(file, line)
#endif
#define _BUG_FLAGS(flags) __BUG_FLAGS(flags)
#define __BUG_FLAGS(flags) asm volatile ( \
".pushsection __bug_table,\"a\"\n\t" \
".align 2\n\t" \
"0: .long 1f - 0b\n\t" \
_BUGVERBOSE_LOCATION(__FILE__, __LINE__) \
".short " #flags "\n\t" \
".popsection\n" \
\
"1: brk %[imm]" \
:: [imm] "i" (BUG_BRK_IMM) \
)
#define BUG() do { \
_BUG_FLAGS(0); \
unreachable(); \
} while (0)
debug: Add _ONCE() logic to report_bug() Josh suggested moving the _ONCE logic inside the trap handler, using a bit in the bug_entry::flags field, avoiding the need for the extra variable. Sadly this only works for WARN_ON_ONCE(), since the others have printk() statements prior to triggering the trap. Still, this saves a fair amount of text and some data: text data filename 10682460 4530992 defconfig-build/vmlinux.orig 10665111 4530096 defconfig-build/vmlinux.patched Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-02-25 07:56:53 +00:00
#define __WARN_FLAGS(flags) _BUG_FLAGS(BUGFLAG_WARNING|(flags))
arm64/BUG: Use BRK instruction for generic BUG traps Currently, the minimal default BUG() implementation from asm- generic is used for arm64. This patch uses the BRK software breakpoint instruction to generate a trap instead, similarly to most other arches, with the generic BUG code generating the dmesg boilerplate. This allows bug metadata to be moved to a separate table and reduces the amount of inline code at BUG and WARN sites. This also avoids clobbering any registers before they can be dumped. To mitigate the size of the bug table further, this patch makes use of the existing infrastructure for encoding addresses within the bug table as 32-bit offsets instead of absolute pointers. (Note that this limits the kernel size to 2GB.) Traps are registered at arch_initcall time for aarch64, but BUG has minimal real dependencies and it is desirable to be able to generate bug splats as early as possible. This patch redirects all debug exceptions caused by BRK directly to bug_handler() until the full debug exception support has been initialised. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-07-24 15:37:48 +00:00
#endif /* ! CONFIG_GENERIC_BUG */
#include <asm-generic/bug.h>
#endif /* ! _ARCH_ARM64_ASM_BUG_H */
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