Re: [PATCH v2 04/16] arm64: Downgrade flush_icache_range to invalidate
From: Mark Rutland <mark.rutland@arm.com>
Date: 2021-05-18 15:55:31
On Mon, May 17, 2021 at 08:51:12AM +0100, Fuad Tabba wrote:
quoted hunk ↗ jump to hunk
Since __flush_dcache_area is called right before, invalidate_icache_range is sufficient in this case. Rewrite the comment to better explain the rationale behind the cache maintenance operations used here. No functional change intended. Possible performance impact due to invalidating only the icache rather than invalidating and cleaning both caches. Reported-by: Catalin Marinas <catalin.marinas@arm.com> Reported-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/linux-arch/20200511110014.lb9PEahJ4hVOYrbwIb_qUHXyNy9KQzNFdb_I3YlzY6A@z/ Signed-off-by: Fuad Tabba <redacted> --- arch/arm64/kernel/machine_kexec.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c index 90a335c74442..ecd8915e02e1 100644 --- a/arch/arm64/kernel/machine_kexec.c +++ b/arch/arm64/kernel/machine_kexec.c@@ -68,10 +68,14 @@ int machine_kexec_post_load(struct kimage *kimage) kimage->arch.kern_reloc = __pa(reloc_code); kexec_image_info(kimage); - /* Flush the reloc_code in preparation for its execution. */ + /* + * For execution with the MMU off and I-cache on, reloc_code needs to be + * cleaned to the PoC and invalidated from the I-cache. + */
Minor nit, but the I-cache is *always* on (SCTLR.I affects the attributes used for fetches into the I-caches), so it would be slightly better to drop the "and I-cache on" words. Otherwise, this looks good to me. Mark.
__flush_dcache_area(reloc_code, arm64_relocate_new_kernel_size); - flush_icache_range((uintptr_t)reloc_code, (uintptr_t)reloc_code + - arm64_relocate_new_kernel_size); + invalidate_icache_range((uintptr_t)reloc_code, + (uintptr_t)reloc_code + + arm64_relocate_new_kernel_size); return 0; } -- 2.31.1.751.gd2f1c929bd-goog
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