[PATCH V2] 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 --- V2: Rename get_fpu_regs() to save_fpu_regs().

arch/loongarch/include/asm/fpu.h | 22 ++++++++++++++++++---- arch/loongarch/kernel/ptrace.c | 4 ++++ 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/arch/loongarch/include/asm/fpu.h b/arch/loongarch/include/asm/fpu.h index b541f6248837..08a45e9fd15c 100644 --- 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 a0767c3a0f0a..9a75dc43eb29 100644 --- 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);