diff options
| author | Will Deacon <will@kernel.org> | 2024-05-22 11:53:05 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2024-05-22 11:55:00 +0100 |
| commit | f481bb32d60e45fb3d19ea68ce79c5629f3fc3a0 (patch) | |
| tree | f61cd1828a3efd8274f877d3bad473e4f0bf2641 /arch | |
| parent | ffbf4fb9b5c12ff878a10ea17997147ea4ebea6f (diff) | |
Reapply "arm64: fpsimd: Implement lazy restore for kernel mode FPSIMD"
This reverts commit b8995a18417088bb53f87c49d200ec72a9dd4ec1.
Ard managed to reproduce the dm-crypt corruption problem and got to the
bottom of it, so re-apply the problematic patch in preparation for
fixing things properly.
Cc: stable@vger.kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/include/asm/processor.h | 1 | ||||
| -rw-r--r-- | arch/arm64/kernel/fpsimd.c | 18 |
2 files changed, 19 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index 4f122b932cca..f77371232d8c 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -171,6 +171,7 @@ struct thread_struct { struct debug_info debug; /* debugging */ struct user_fpsimd_state kernel_fpsimd_state; + unsigned int kernel_fpsimd_cpu; #ifdef CONFIG_ARM64_PTR_AUTH struct ptrauth_keys_user keys_user; #ifdef CONFIG_ARM64_PTR_AUTH_KERNEL diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index e9d70dc91511..ebb0158997ca 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -1509,12 +1509,30 @@ void do_fpsimd_exc(unsigned long esr, struct pt_regs *regs) static void fpsimd_load_kernel_state(struct task_struct *task) { + struct cpu_fp_state *last = this_cpu_ptr(&fpsimd_last_state); + + /* + * Elide the load if this CPU holds the most recent kernel mode + * FPSIMD context of the current task. + */ + if (last->st == &task->thread.kernel_fpsimd_state && + task->thread.kernel_fpsimd_cpu == smp_processor_id()) + return; + fpsimd_load_state(&task->thread.kernel_fpsimd_state); } static void fpsimd_save_kernel_state(struct task_struct *task) { + struct cpu_fp_state cpu_fp_state = { + .st = &task->thread.kernel_fpsimd_state, + .to_save = FP_STATE_FPSIMD, + }; + fpsimd_save_state(&task->thread.kernel_fpsimd_state); + fpsimd_bind_state_to_cpu(&cpu_fp_state); + + task->thread.kernel_fpsimd_cpu = smp_processor_id(); } void fpsimd_thread_switch(struct task_struct *next) |