| Message ID | 20221114144042.3001140-1-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: make is_ttbrX_addr() noinstr-safe | expand |
On Mon, 14 Nov 2022 14:40:42 +0000, Mark Rutland wrote: > We use is_ttbr0_addr() in noinstr code, but as it's only marked as > inline, it's theoretically possible for the compiler to place it > out-of-line and instrument it, which would be problematic. > > Mark is_ttbr0_addr() as __always_inline such that that can safely be > used from noinstr code. For consistency, do the same to is_ttbr1_addr(). > Note that while is_ttbr1_addr() calls arch_kasan_reset_tag(), this is a > macro (and its callees are either macros or __always_inline), so there > is not a risk of transient instrumentation. > > [...] Applied to arm64 (for-next/trivial), thanks! [1/1] arm64: make is_ttbrX_addr() noinstr-safe https://git.kernel.org/arm64/c/d8c1d798a2e5 Cheers,
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index 445aa3af3b76..400f8956328b 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -308,13 +308,13 @@ static inline void compat_start_thread(struct pt_regs *regs, unsigned long pc, } #endif -static inline bool is_ttbr0_addr(unsigned long addr) +static __always_inline bool is_ttbr0_addr(unsigned long addr) { /* entry assembly clears tags for TTBR0 addrs */ return addr < TASK_SIZE; } -static inline bool is_ttbr1_addr(unsigned long addr) +static __always_inline bool is_ttbr1_addr(unsigned long addr) { /* TTBR1 addresses may have a tag if KASAN_SW_TAGS is in use */ return arch_kasan_reset_tag(addr) >= PAGE_OFFSET;
We use is_ttbr0_addr() in noinstr code, but as it's only marked as inline, it's theoretically possible for the compiler to place it out-of-line and instrument it, which would be problematic. Mark is_ttbr0_addr() as __always_inline such that that can safely be used from noinstr code. For consistency, do the same to is_ttbr1_addr(). Note that while is_ttbr1_addr() calls arch_kasan_reset_tag(), this is a macro (and its callees are either macros or __always_inline), so there is not a risk of transient instrumentation. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> --- arch/arm64/include/asm/processor.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)