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Thu, 20 May 2021 14:13:18 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 543D511D4; Thu, 20 May 2021 07:13:16 -0700 (PDT) Received: from C02TD0UTHF1T.local (unknown [10.57.7.235]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8B2FB3F73B; Thu, 20 May 2021 07:13:14 -0700 (PDT) Date: Thu, 20 May 2021 15:13:12 +0100 From: Mark Rutland To: Fuad Tabba Cc: linux-arm-kernel@lists.infradead.org, will@kernel.org, catalin.marinas@arm.com, maz@kernel.org, ardb@kernel.org, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, robin.murphy@arm.com Subject: Re: [PATCH v3 06/18] arm64: Do not enable uaccess for invalidate_icache_range Message-ID: <20210520141312.GI17233@C02TD0UTHF1T.local> References: <20210520124406.2731873-1-tabba@google.com> <20210520124406.2731873-7-tabba@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210520124406.2731873-7-tabba@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210520_071317_218246_8F2A4729 X-CRM114-Status: GOOD ( 18.09 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, May 20, 2021 at 01:43:54PM +0100, Fuad Tabba wrote: > invalidate_icache_range() works on the kernel linear map, and Minor nit: this works on kernel addresses generally (e.g. vmalloc), so we could say "kernel addresses" rather than "the kernel linear map". > doesn't need uaccess. Remove the code that toggles > uaccess_ttbr0_enable, as well as the code that emits an entry > into the exception table (via the macro > invalidate_icache_by_line). > > Changes return type of invalidate_icache_range() from int (which > used to indicate a fault) to void, since it doesn't need uaccess > and won't fault. Note that return value was never checked by any > of the callers. > > No functional change intended. > Possible performance impact due to the reduced number of > instructions. > > Reported-by: Catalin Marinas > Reported-by: Will Deacon > Link: https://lore.kernel.org/linux-arch/20200511110014.lb9PEahJ4hVOYrbwIb_qUHXyNy9KQzNFdb_I3YlzY6A@z/ > Signed-off-by: Fuad Tabba Acked-by: Mark Rutland Mark. > --- > arch/arm64/include/asm/cacheflush.h | 2 +- > arch/arm64/mm/cache.S | 11 +---------- > 2 files changed, 2 insertions(+), 11 deletions(-) > > diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h > index 52e5c1623224..a586afa84172 100644 > --- a/arch/arm64/include/asm/cacheflush.h > +++ b/arch/arm64/include/asm/cacheflush.h > @@ -57,7 +57,7 @@ > * - size - region size > */ > extern void __flush_icache_range(unsigned long start, unsigned long end); > -extern int invalidate_icache_range(unsigned long start, unsigned long end); > +extern void invalidate_icache_range(unsigned long start, unsigned long end); > extern void __flush_dcache_area(void *addr, size_t len); > extern void __inval_dcache_area(void *addr, size_t len); > extern void __clean_dcache_area_poc(void *addr, size_t len); > diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S > index c6bc3b8138e1..7318a40dd6ca 100644 > --- a/arch/arm64/mm/cache.S > +++ b/arch/arm64/mm/cache.S > @@ -97,21 +97,12 @@ SYM_FUNC_END(__flush_cache_user_range) > */ > SYM_FUNC_START(invalidate_icache_range) > alternative_if ARM64_HAS_CACHE_DIC > - mov x0, xzr > isb > ret > alternative_else_nop_endif > > - uaccess_ttbr0_enable x2, x3, x4 > - > - invalidate_icache_by_line x0, x1, x2, x3, 2f > - mov x0, xzr > -1: > - uaccess_ttbr0_disable x1, x2 > + invalidate_icache_by_line x0, x1, x2, x3 > ret > -2: > - mov x0, #-EFAULT > - b 1b > SYM_FUNC_END(invalidate_icache_range) > > /* > -- > 2.31.1.751.gd2f1c929bd-goog > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel