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Wed, 17 Sep 2025 23:36:11 -0700 (PDT) Date: Thu, 18 Sep 2025 08:35:44 +0200 In-Reply-To: <20250918063539.2640512-7-ardb+git@google.com> Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250918063539.2640512-7-ardb+git@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=2845; i=ardb@kernel.org; h=from:subject; bh=fbTmP4aG6tbBHGWrU82oUT6Reb9I9nyA/9uuGWnWHsA=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JIeP0Cqcpcmo3s9lOdcud6TTT/3/e+Haah27JoTmrPn36k qtkYXWuo5SFQYyLQVZMkUVg9t93O09PlKp1niULM4eVCWQIAxenAEykPJyRYc9Ujxln1/M8UN0U srST+emhX57lN5vdFz69bBItdNUs9xHDP1OjzLYvG7QqeQXWeDWfFnstxjJ5Zu7xFo5XF1s+H1P byAcA X-Mailer: git-send-email 2.51.0.384.g4c02a37b29-goog Message-ID: <20250918063539.2640512-11-ardb+git@google.com> Subject: [PATCH 4/5] arm64/fpsimd: Require kernel NEON begin/end calls from the same scope From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, herbert@gondor.apana.org.au, ebiggers@kernel.org, Ard Biesheuvel , Marc Zyngier , Will Deacon , Mark Rutland , Kees Cook , Catalin Marinas , Mark Brown Content-Type: text/plain; charset="UTF-8" From: Ard Biesheuvel In preparation for making kernel_neon_begin() allocate a stack based buffer for stashing the kernel mode FP/SIMD state on a context switch, redefine kernel_neon_begin() and kernel_neon_end() as macros, in a way that requires them to be called from the same scope, and therefore, running from the same stack frame. Signed-off-by: Ard Biesheuvel --- arch/arm64/include/asm/neon.h | 7 +++++-- arch/arm64/kernel/fpsimd.c | 12 ++++++------ 2 files changed, 11 insertions(+), 8 deletions(-) diff --git a/arch/arm64/include/asm/neon.h b/arch/arm64/include/asm/neon.h index d4b1d172a79b..4e24f1058b55 100644 --- a/arch/arm64/include/asm/neon.h +++ b/arch/arm64/include/asm/neon.h @@ -13,7 +13,10 @@ #define cpu_has_neon() system_supports_fpsimd() -void kernel_neon_begin(void); -void kernel_neon_end(void); +void __kernel_neon_begin(void); +void __kernel_neon_end(void); + +#define kernel_neon_begin() do { __kernel_neon_begin() +#define kernel_neon_end() __kernel_neon_end(); } while (0) #endif /* ! __ASM_NEON_H */ diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index c37f02d7194e..d7eb073d1366 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -1833,7 +1833,7 @@ void fpsimd_save_and_flush_cpu_state(void) * The caller may freely use the FPSIMD registers until kernel_neon_end() is * called. */ -void kernel_neon_begin(void) +void __kernel_neon_begin(void) { if (WARN_ON(!system_supports_fpsimd())) return; @@ -1875,7 +1875,7 @@ void kernel_neon_begin(void) put_cpu_fpsimd_context(); } -EXPORT_SYMBOL_GPL(kernel_neon_begin); +EXPORT_SYMBOL_GPL(__kernel_neon_begin); /* * kernel_neon_end(): give the CPU FPSIMD registers back to the current task @@ -1886,7 +1886,7 @@ EXPORT_SYMBOL_GPL(kernel_neon_begin); * The caller must not use the FPSIMD registers after this function is called, * unless kernel_neon_begin() is called again in the meantime. */ -void kernel_neon_end(void) +void __kernel_neon_end(void) { if (!system_supports_fpsimd()) return; @@ -1902,7 +1902,7 @@ void kernel_neon_end(void) else clear_thread_flag(TIF_KERNEL_FPSTATE); } -EXPORT_SYMBOL_GPL(kernel_neon_end); +EXPORT_SYMBOL_GPL(__kernel_neon_end); #ifdef CONFIG_EFI @@ -1936,7 +1936,7 @@ void __efi_fpsimd_begin(void) WARN_ON(preemptible()); if (may_use_simd()) { - kernel_neon_begin(); + __kernel_neon_begin(); } else { /* * If !efi_sve_state, SVE can't be in use yet and doesn't need @@ -1985,7 +1985,7 @@ void __efi_fpsimd_end(void) return; if (!efi_fpsimd_state_used) { - kernel_neon_end(); + __kernel_neon_end(); } else { if (system_supports_sve() && efi_sve_state_used) { bool ffr = true; -- 2.51.0.384.g4c02a37b29-goog