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| author | Heyi Guo <guoheyi@huawei.com> | 2019-12-02 19:37:02 +0800 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2019-12-06 14:11:31 +0000 |
| commit | de858040ee80e6f41bf0b40090f1c71f966a61b3 (patch) | |
| tree | 5da0192b34f3ccb1cb3fa738839a42a7fe65c37b | |
| parent | 70927d02d409b5a79c3ed040ace5017da8284ede (diff) | |
| download | linux-de858040ee80e6f41bf0b40090f1c71f966a61b3.tar.bz2 | |
arm64: entry: refine comment of stack overflow check
Stack overflow checking can be done by testing sp & (1 << THREAD_SHIFT)
only for the stacks are aligned to (2 << THREAD_SHIFT) with size of
(1 << THREAD_SIZE), and this is the case when CONFIG_VMAP_STACK is set.
Fix the code comment to avoid confusion.
Cc: Will Deacon <will@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Heyi Guo <guoheyi@huawei.com>
[catalin.marinas@arm.com: Updated comment following Mark's suggestion]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
| -rw-r--r-- | arch/arm64/kernel/entry.S | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 583f71abbe98..7c6a0a41676f 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -76,7 +76,8 @@ alternative_else_nop_endif #ifdef CONFIG_VMAP_STACK /* * Test whether the SP has overflowed, without corrupting a GPR. - * Task and IRQ stacks are aligned to (1 << THREAD_SHIFT). + * Task and IRQ stacks are aligned so that SP & (1 << THREAD_SHIFT) + * should always be zero. */ add sp, sp, x0 // sp' = sp + x0 sub x0, sp, x0 // x0' = sp' - x0 = (sp + x0) - x0 = sp |