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| author | Ard Biesheuvel <ardb@kernel.org> | 2022-01-26 11:40:02 +0100 |
|---|---|---|
| committer | Ard Biesheuvel <ardb@kernel.org> | 2022-02-09 10:13:10 +0100 |
| commit | 1f640552d9878f2dbcbd46c78078e4ea2eb2b262 (patch) | |
| tree | 5be395246addb7b90d391f108614eaad8ca0e30c /arch/arm/mach-exynos | |
| parent | ARM: kprobes: treat R7 as the frame pointer register in Thumb2 builds (diff) | |
| download | linux-1f640552d9878f2dbcbd46c78078e4ea2eb2b262.tar.xz linux-1f640552d9878f2dbcbd46c78078e4ea2eb2b262.zip | |
ARM: cacheflush: avoid clobbering the frame pointer
Thumb2 uses R7 rather than R11 as the frame pointer, and even if we
rarely use a frame pointer to begin with when building in Thumb2 mode,
there are cases where it is required by the compiler (Clang when
inserting profiling hooks via -pg)
However, preserving and restoring the frame pointer is risky, as any
unhandled exceptions raised in the mean time will produce a bogus
backtrace, and it would be better not to touch the frame pointer at all.
This is the case even when CONFIG_FRAME_POINTER is not set, as the
unwind directive used by the unwinder may also use R7 or R11 as the
unwind anchor, even if the frame pointer is not managed strictly
according to the frame pointer ABI.
So let's tweak the cacheflush asm code not to clobber R7 or R11 at all,
so that we can drop R7 from the clobber lists of the inline asm blocks
that call these routines, and remove the code that preserves/restores
R11.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Diffstat (limited to 'arch/arm/mach-exynos')
| -rw-r--r-- | arch/arm/mach-exynos/mcpm-exynos.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/arch/arm/mach-exynos/mcpm-exynos.c b/arch/arm/mach-exynos/mcpm-exynos.c index cd861c57d5ad..fd0dbeb93357 100644 --- a/arch/arm/mach-exynos/mcpm-exynos.c +++ b/arch/arm/mach-exynos/mcpm-exynos.c @@ -35,7 +35,6 @@ static bool secure_firmware __ro_after_init; */ #define exynos_v7_exit_coherency_flush(level) \ asm volatile( \ - "stmfd sp!, {fp, ip}\n\t"\ "mrc p15, 0, r0, c1, c0, 0 @ get SCTLR\n\t" \ "bic r0, r0, #"__stringify(CR_C)"\n\t" \ "mcr p15, 0, r0, c1, c0, 0 @ set SCTLR\n\t" \ @@ -50,11 +49,10 @@ static bool secure_firmware __ro_after_init; "mcr p15, 0, r0, c1, c0, 1 @ set ACTLR\n\t" \ "isb\n\t" \ "dsb\n\t" \ - "ldmfd sp!, {fp, ip}" \ : \ : "Ir" (pmu_base_addr + S5P_INFORM0) \ - : "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", \ - "r9", "r10", "lr", "memory") + : "r0", "r1", "r2", "r3", "r4", "r5", "r6", \ + "r9", "r10", "ip", "lr", "memory") static int exynos_cpu_powerup(unsigned int cpu, unsigned int cluster) { |