path: root/arch/arm64/include/asm/assembler.h
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authorMark Rutland <mark.rutland@arm.com>2017-07-26 11:14:53 +0100
committerMark Rutland <mark.rutland@arm.com>2017-08-08 16:28:24 +0100
commit2d0e751a4789fc5ab4a5c9de5d6407b41fdfbbf0 (patch)
tree4cb9af0de3b5b9b6d8b9e90d8171cabc1071b1f7 /arch/arm64/include/asm/assembler.h
parentarm64: Add ASM_BUG() (diff)
arm64: consistently use bl for C exception entry
In most cases, our exception entry assembly branches to C handlers with a BL instruction, but in cases where we do not expect to return, we use B instead. While this is correct today, it means that backtraces for fatal exceptions miss the entry assembly (as the LR is stale at the point we call C code), while non-fatal exceptions have the entry assembly in the LR. In subsequent patches, we will need the LR to be set in these cases in order to backtrace reliably. This patch updates these sites to use a BL, ensuring consistency, and preparing for backtrace rework. An ASM_BUG() is added after each of these new BLs, which both catches unexpected returns, and ensures that the LR value doesn't point to another function label. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Will Deacon <will.deacon@arm.com>
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