diff options
| author | Mark Rutland <mark.rutland@arm.com> | 2016-01-06 11:05:27 +0000 |
|---|---|---|
| committer | Alex Shi <alex.shi@linaro.org> | 2016-10-20 16:23:47 +0800 |
| commit | 04fcc8d8a52c0f667c54434aa7ad45126ba20ab0 (patch) | |
| tree | 9cfc6d25b7de6e74ce35dfc98ade4b9f0cbeac75 /arch/arm64/kernel/head.S | |
| parent | 0b5c41b49b108eb8ef9448330a42e0fde504a2b6 (diff) | |
arm64: head.S: use memset to clear BSS
Currently we use an open-coded memzero to clear the BSS. As it is a
trivial implementation, it is sub-optimal.
Our optimised memset doesn't use the stack, is position-independent, and
for the memzero case can use of DC ZVA to clear large blocks
efficiently. In __mmap_switched the MMU is on and there are no live
caller-saved registers, so we can safely call an uninstrumented memset.
This patch changes __mmap_switched to use memset when clearing the BSS.
We use the __pi_memset alias so as to avoid any instrumentation in all
kernel configurations.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
(cherry picked from commit 2a803c4db615d85126c5c7afd5849a3cfde71422)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
Diffstat (limited to 'arch/arm64/kernel/head.S')
| -rw-r--r-- | arch/arm64/kernel/head.S | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index b685257926f0..4d37c413da4d 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -415,14 +415,13 @@ ENDPROC(__create_page_tables) */ .set initial_sp, init_thread_union + THREAD_START_SP __mmap_switched: - adr_l x6, __bss_start - adr_l x7, __bss_stop - -1: cmp x6, x7 - b.hs 2f - str xzr, [x6], #8 // Clear BSS - b 1b -2: + // Clear BSS + adr_l x0, __bss_start + mov x1, xzr + adr_l x2, __bss_stop + sub x2, x2, x0 + bl __pi_memset + adr_l sp, initial_sp, x4 str_l x21, __fdt_pointer, x5 // Save FDT pointer str_l x24, memstart_addr, x6 // Save PHYS_OFFSET |