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

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This is a port of commit 379eb01c21 ("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>
This commit is contained in:
Huacai Chen 2023-08-26 22:21:57 +08:00
parent c337c849ab
commit 656f9aec07
2 changed files with 22 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

22
arch/loongarch/include/asm/fpu.h
View file

@ -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)

4
arch/loongarch/kernel/ptrace.c
View file

@ -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);