FAILED: patch "[PATCH] LoongArch: Ensure FP/SIMD registers in the core dump file is" failed to apply to 6.4-stable tree

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 <[email protected]>.

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 '<[email protected]>' --in-reply-to '2023082705-predator-enjoyable-15fb@gregkh' --subject-prefix 'PATCH 6.4.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 656f9aec07dba7c61d469727494a5d1b18d0bef4 Mon Sep 17 00:00:00 2001
From: Huacai Chen <[email protected]>
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 [email protected]

Signed-off-by Huacai Chen <[email protected]>

arch/loongarch/include/asm/fpu.h +18 -4

index b541f6248837..c2d8962fda00 100644
@@ -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)

arch/loongarch/kernel/ptrace.c +4 -0

index a0767c3a0f0a..f72adbf530c6 100644
@@ -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);

Quoted 16 lines · On Sun, Aug 27, 2023 at 2:45 PM <[email protected]> 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 <[email protected]>.

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 '<[email protected]>' --in-reply-to '2023082705-predator-enjoyable-15fb@gregkh' --subject-prefix 'PATCH 6.4.y' HEAD^..

Quoted 1 line

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

Quoted 17 lines · Huacai Chen

Quoted 16 lines · On Sun, Aug 27, 2023 at 2:45 PM <[email protected]> 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 <[email protected]>.

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 '<[email protected]>' --in-reply-to '2023082705-predator-enjoyable-15fb@gregkh' --subject-prefix 'PATCH 6.4.y' HEAD^..

Quoted 3 lines

Quoted 1 line

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

I do not understand, sorry. Is this relevant for 6.4.y? If so, can you provide a working backport?

thanks,

greg k-h