On Sun, Aug 27, 2023 at 2:45 PM gregkh@linuxfoundation.org wrote:

The patch below does not apply to the 6.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.4.y git checkout FETCH_HEAD git cherry-pick -x 656f9aec07dba7c61d469727494a5d1b18d0bef4 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023082705-predator-enjoyable-15fb@gregkh' --subject-prefix 'PATCH 6.4.y' HEAD^..

Possible dependencies:

I'm sorry, this is my mistake. 6.4 also need to cut the simd_get() part, because simd is only supported since 6.5

Huacai

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 656f9aec07dba7c61d469727494a5d1b18d0bef4 Mon Sep 17 00:00:00 2001 From: Huacai Chen chenhuacai@kernel.org Date: Sat, 26 Aug 2023 22:21:57 +0800 Subject: [PATCH] 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 b541f6248837..c2d8962fda00 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..f72adbf530c6 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);