LoongArch: Ensure FP/SIMD registers in the core dump file is up to date

This is a port of commit 379eb01c21795edb4c ("riscv: Ensure the value
of FP registers in the core dump file is up to date").

The values of FP/SIMD registers in the core dump file come from the
thread.fpu. However, kernel saves the FP/SIMD registers only before
scheduling out the process. If no process switch happens during the
exception handling, kernel will not have a chance to save the latest
values of FP/SIMD registers. So it may cause their values in the core
dump file incorrect. To solve this problem, force fpr_get()/simd_get()
to save the FP/SIMD registers into the thread.fpu if the target task
equals the current task.

Cc: stable@vger.kernel.org
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/arch/loongarch/include/asm/fpu.h b/arch/loongarch/include/asm/fpu.h
index b541f62..c2d8962 100644 (file)
--- a/arch/loongarch/include/asm/fpu.h
+++ b/arch/loongarch/include/asm/fpu.h
@@ -173,16 +173,30 @@ static inline void restore_fp(struct task_struct *tsk)
                _restore_fp(&tsk->thread.fpu);
 }
 
-static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
+static inline void save_fpu_regs(struct task_struct *tsk)
 {
+       unsigned int euen;
+
        if (tsk == current) {
                preempt_disable();
-               if (is_fpu_owner())
+
+               euen = csr_read32(LOONGARCH_CSR_EUEN);
+
+#ifdef CONFIG_CPU_HAS_LASX
+               if (euen & CSR_EUEN_LASXEN)
+                       _save_lasx(&current->thread.fpu);
+               else
+#endif
+#ifdef CONFIG_CPU_HAS_LSX
+               if (euen & CSR_EUEN_LSXEN)
+                       _save_lsx(&current->thread.fpu);
+               else
+#endif
+               if (euen & CSR_EUEN_FPEN)
                        _save_fp(&current->thread.fpu);
+
                preempt_enable();
        }
-
-       return tsk->thread.fpu.fpr;
 }
 
 static inline int is_simd_owner(void)

diff --git a/arch/loongarch/kernel/ptrace.c b/arch/loongarch/kernel/ptrace.c
index a0767c3..f72adbf 100644 (file)
--- a/arch/loongarch/kernel/ptrace.c
+++ b/arch/loongarch/kernel/ptrace.c
@@ -147,6 +147,8 @@ static int fpr_get(struct task_struct *target,
 {
        int r;
 
+       save_fpu_regs(target);
+
        if (sizeof(target->thread.fpu.fpr[0]) == sizeof(elf_fpreg_t))
                r = gfpr_get(target, &to);
        else
@@ -278,6 +280,8 @@ static int simd_get(struct task_struct *target,
 {
        const unsigned int wr_size = NUM_FPU_REGS * regset->size;
 
+       save_fpu_regs(target);
+
        if (!tsk_used_math(target)) {
                /* The task hasn't used FP or LSX, fill with 0xff */
                copy_pad_fprs(target, regset, &to, 0);