Commit d8c1d798 authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon
Browse files

arm64: make is_ttbrX_addr() noinstr-safe 



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: default avatarMark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20221114144042.3001140-1-mark.rutland@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 9e75e74b

arch/arm64/include/asm/processor.h

+2 −2
Original line number Diff line number Diff line
@@ -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;