Revert "arm64: fpsimd: Implement lazy restore for kernel mode FPSIMD"

This reverts commit 2632e25217696712681dd1f3ecc0d71624ea3b23.

Johannes (and others) report data corruption with dm-crypt on Apple M1
which has been bisected to this change. Revert the offending commit
while we figure out what's going on.

Cc: stable@vger.kernel.org
Reported-by: Johannes Nixdorf <mixi@shadowice.org>
Link: https://lore.kernel.org/all/D1B7GPIR9K1E.5JFV37G0YTIF@shadowice.org/
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index f77371232d8c6d542c7df057feea2e21752f34f2..4f122b932ccaccde0530b5abf9fc2bc9ee129226 100644 (file)
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -171,7 +171,6 @@ 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 ebb0158997cab5e32fcefe7ed50a043095ee9262..e9d70dc915117e545fbdec2b527339a1f1245637 100644 (file)
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1509,30 +1509,12 @@ 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)