Messages in this thread Patch in this message | | | From | Vincenzo Frascino <> | Subject | [PATCH v3 4/4] arm64: mte: Optimize mte_assign_mem_tag_range() | Date | Fri, 15 Jan 2021 12:00:43 +0000 |
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mte_assign_mem_tag_range() is called on production KASAN HW hot paths. It makes sense to optimize it in an attempt to reduce the overhead.
Optimize mte_assign_mem_tag_range() based on the indications provided at [1].
[1] https://lore.kernel.org/r/CAAeHK+wCO+J7D1_T89DG+jJrPLk3X9RsGFKxJGd0ZcUFjQT-9Q@mail.gmail.com/
Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> --- arch/arm64/include/asm/mte.h | 26 +++++++++++++++++++++++++- arch/arm64/lib/mte.S | 15 --------------- 2 files changed, 25 insertions(+), 16 deletions(-)
diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h index 1a715963d909..9730f2b07b79 100644 --- a/arch/arm64/include/asm/mte.h +++ b/arch/arm64/include/asm/mte.h @@ -49,7 +49,31 @@ long get_mte_ctrl(struct task_struct *task); int mte_ptrace_copy_tags(struct task_struct *child, long request, unsigned long addr, unsigned long data); -void mte_assign_mem_tag_range(void *addr, size_t size); +static inline void mte_assign_mem_tag_range(void *addr, size_t size) +{ + u64 _addr = (u64)addr; + u64 _end = _addr + size; + + /* + * This function must be invoked from an MTE enabled context. + * + * Note: The address must be non-NULL and MTE_GRANULE_SIZE aligned and + * size must be non-zero and MTE_GRANULE_SIZE aligned. + */ + do { + /* + * 'asm volatile' is required to prevent the compiler to move + * the statement outside of the loop. + */ + asm volatile(__MTE_PREAMBLE "stg %0, [%0]" + : + : "r" (_addr) + : "memory"); + + _addr += MTE_GRANULE_SIZE; + } while (_addr < _end); +} + #else /* CONFIG_ARM64_MTE */ diff --git a/arch/arm64/lib/mte.S b/arch/arm64/lib/mte.S index 9e1a12e10053..a0a650451510 100644 --- a/arch/arm64/lib/mte.S +++ b/arch/arm64/lib/mte.S @@ -150,18 +150,3 @@ SYM_FUNC_START(mte_restore_page_tags) ret SYM_FUNC_END(mte_restore_page_tags) -/* - * Assign allocation tags for a region of memory based on the pointer tag - * x0 - source pointer - * x1 - size - * - * Note: The address must be non-NULL and MTE_GRANULE_SIZE aligned and - * size must be non-zero and MTE_GRANULE_SIZE aligned. - */ -SYM_FUNC_START(mte_assign_mem_tag_range) -1: stg x0, [x0] - add x0, x0, #MTE_GRANULE_SIZE - subs x1, x1, #MTE_GRANULE_SIZE - b.gt 1b - ret -SYM_FUNC_END(mte_assign_mem_tag_range) -- 2.30.0
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