Commit 656f9aec authored by Huacai Chen's avatar Huacai Chen
Browse files

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



This is a port of commit 379eb01c ("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: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent c337c849

arch/loongarch/include/asm/fpu.h

+18 −4
Original line number Diff line number Diff line
@@ -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
Original line number Diff line number Diff line
@@ -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);