Merge tag 'fpsimd-on-stack-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux

Pull arm64 FPSIMD on-stack buffer updates from Eric Biggers:
 "This is a core arm64 change. However, I was asked to take this because
  most uses of kernel-mode FPSIMD are in crypto or CRC code.

  In v6.8, the size of task_struct on arm64 increased by 528 bytes due
  to the new 'kernel_fpsimd_state' field. This field was added to allow
  kernel-mode FPSIMD code to be preempted.

  Unfortunately, 528 bytes is kind of a lot for task_struct. This
  regression in the task_struct size was noticed and reported.

  Recover that space by making this state be allocated on the stack at
  the beginning of each kernel-mode FPSIMD section.

  To make it easier for all the users of kernel-mode FPSIMD to do that
  correctly, introduce and use a 'scoped_ksimd' abstraction"

* tag 'fpsimd-on-stack-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux: (23 commits)
  lib/crypto: arm64: Move remaining algorithms to scoped ksimd API
  lib/crypto: arm/blake2b: Move to scoped ksimd API
  arm64/fpsimd: Allocate kernel mode FP/SIMD buffers on the stack
  arm64/fpu: Enforce task-context only for generic kernel mode FPU
  net/mlx5: Switch to more abstract scoped ksimd guard API on arm64
  arm64/xorblocks:  Switch to 'ksimd' scoped guard API
  crypto/arm64: sm4 - Switch to 'ksimd' scoped guard API
  crypto/arm64: sm3 - Switch to 'ksimd' scoped guard API
  crypto/arm64: sha3 - Switch to 'ksimd' scoped guard API
  crypto/arm64: polyval - Switch to 'ksimd' scoped guard API
  crypto/arm64: nhpoly1305 - Switch to 'ksimd' scoped guard API
  crypto/arm64: aes-gcm - Switch to 'ksimd' scoped guard API
  crypto/arm64: aes-blk - Switch to 'ksimd' scoped guard API
  crypto/arm64: aes-ccm - Switch to 'ksimd' scoped guard API
  raid6: Move to more abstract 'ksimd' guard API
  crypto: aegis128-neon - Move to more abstract 'ksimd' guard API
  crypto/arm64: sm4-ce-gcm - Avoid pointless yield of the NEON unit
  crypto/arm64: sm4-ce-ccm - Avoid pointless yield of the NEON unit
  crypto/arm64: aes-ce-ccm - Avoid pointless yield of the NEON unit
  lib/crc: Switch ARM and arm64 to 'ksimd' scoped guard API
  ...

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/arm/include/asm/simd.h b/arch/arm/include/asm/simd.h
index be08a8da046f..8549fa8b7253 100644
--- a/arch/arm/include/asm/simd.h
+++ b/arch/arm/include/asm/simd.h
@@ -2,14 +2,21 @@
 #ifndef _ASM_SIMD_H
 #define _ASM_SIMD_H
 
+#include <linux/cleanup.h>
 #include <linux/compiler_attributes.h>
 #include <linux/preempt.h>
 #include <linux/types.h>
 
+#include <asm/neon.h>
+
 static __must_check inline bool may_use_simd(void)
 {
 	return IS_ENABLED(CONFIG_KERNEL_MODE_NEON) && !in_hardirq()
 	       && !irqs_disabled();
 }
 
+DEFINE_LOCK_GUARD_0(ksimd, kernel_neon_begin(), kernel_neon_end())
+
+#define scoped_ksimd()	scoped_guard(ksimd)
+
 #endif	/* _ASM_SIMD_H */