Currently. we can only use BUG() from C code, though there are
situations where we would like an equivalent mechanism in assembly code.
This patch refactors our BUG() definition such that it can be used in
either C or assembly, in the form of a new ASM_BUG().
The refactoring requires the removal of escape sequences, such as '\n'
and '\t', but these aren't strictly necessary as we can use ';' to
terminate assembler statements.
The low-level assembly is factored out into <asm/asm-bug.h>, with
<asm/bug.h> retained as the C wrapper.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Martin <dave.martin@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
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>
- kdump support, including two necessary memblock additions:
memblock_clear_nomap() and memblock_cap_memory_range()
- ARMv8.3 HWCAP bits for JavaScript conversion instructions, complex
numbers and weaker release consistency
- arm64 ACPI platform MSI support
- arm perf updates: ACPI PMU support, L3 cache PMU in some Qualcomm
SoCs, Cortex-A53 L2 cache events and DTLB refills, MAINTAINERS update
for DT perf bindings
- architected timer errata framework (the arch/arm64 changes only)
- support for DMA_ATTR_FORCE_CONTIGUOUS in the arm64 iommu DMA API
- arm64 KVM refactoring to use common system register definitions
- remove support for ASID-tagged VIVT I-cache (no ARMv8 implementation
using it and deprecated in the architecture) together with some
I-cache handling clean-up
- PE/COFF EFI header clean-up/hardening
- define BUG() instruction without CONFIG_BUG
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Catalin Marinas:
- kdump support, including two necessary memblock additions:
memblock_clear_nomap() and memblock_cap_memory_range()
- ARMv8.3 HWCAP bits for JavaScript conversion instructions, complex
numbers and weaker release consistency
- arm64 ACPI platform MSI support
- arm perf updates: ACPI PMU support, L3 cache PMU in some Qualcomm
SoCs, Cortex-A53 L2 cache events and DTLB refills, MAINTAINERS update
for DT perf bindings
- architected timer errata framework (the arch/arm64 changes only)
- support for DMA_ATTR_FORCE_CONTIGUOUS in the arm64 iommu DMA API
- arm64 KVM refactoring to use common system register definitions
- remove support for ASID-tagged VIVT I-cache (no ARMv8 implementation
using it and deprecated in the architecture) together with some
I-cache handling clean-up
- PE/COFF EFI header clean-up/hardening
- define BUG() instruction without CONFIG_BUG
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (92 commits)
arm64: Fix the DMA mmap and get_sgtable API with DMA_ATTR_FORCE_CONTIGUOUS
arm64: Print DT machine model in setup_machine_fdt()
arm64: pmu: Wire-up Cortex A53 L2 cache events and DTLB refills
arm64: module: split core and init PLT sections
arm64: pmuv3: handle pmuv3+
arm64: Add CNTFRQ_EL0 trap handler
arm64: Silence spurious kbuild warning on menuconfig
arm64: pmuv3: use arm_pmu ACPI framework
arm64: pmuv3: handle !PMUv3 when probing
drivers/perf: arm_pmu: add ACPI framework
arm64: add function to get a cpu's MADT GICC table
drivers/perf: arm_pmu: split out platform device probe logic
drivers/perf: arm_pmu: move irq request/free into probe
drivers/perf: arm_pmu: split cpu-local irq request/free
drivers/perf: arm_pmu: rename irq request/free functions
drivers/perf: arm_pmu: handle no platform_device
drivers/perf: arm_pmu: simplify cpu_pmu_request_irqs()
drivers/perf: arm_pmu: factor out pmu registration
drivers/perf: arm_pmu: fold init into alloc
drivers/perf: arm_pmu: define armpmu_init_fn
...
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>
This mirrors commit e9c38ceba8 ("ARM: 8455/1: define __BUG as
asm(BUG_INSTR) without CONFIG_BUG") to make the behavior of
arm64 consistent with arm and x86, and avoids lots of warnings in
randconfig builds, such as:
kernel/seccomp.c: In function '__seccomp_filter':
kernel/seccomp.c:666:1: error: no return statement in function returning non-void [-Werror=return-type]
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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>
Currently, using BUG_ON() in header files is cumbersome, due to the fact
that asm/bug.h transitively includes a lot of other header files, resulting
in the actual BUG_ON() invocation appearing before its definition in the
preprocessor input. So let's reverse the #include dependency between
asm/bug.h and asm/debug-monitors.h, by moving the definition of BUG_BRK_IMM
from the latter to the former. Also fix up one user of asm/debug-monitors.h
which relied on a transitive include.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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>
