Commit eba5f68c authored by Hongchen Zhang's avatar Hongchen Zhang
Browse files

LoongArch: optimize for syscall return 

LoongArch inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6BWFP



--------------------------------

If the syscall is not rt_sigreturn,there is no need to do
RESTORE_STATIC and RESTORE_TEMP.

Signed-off-by: default avatarHongchen Zhang <zhanghongchen@loongson.cn>
Change-Id: I61804bb16ce678dd39e9f197bd88d91e13b972cb
parent d8911a28

arch/loongarch/kernel/entry.S

+13 −4
Original line number Diff line number Diff line
@@ -14,13 +14,14 @@ 
#include <asm/regdef.h>

#include <asm/stackframe.h>

#include <asm/thread_info.h>

#include <asm/unistd.h>



	.text

	.cfi_sections	.debug_frame

	.align	5

SYM_FUNC_START(handle_syscall)

	csrrd	t0, PERCPU_BASE_KS

	la.abs	t1, kernelsp

	la.pcrel t1, kernelsp

	add.d	t1, t1, t0

	move	t2, sp

	ld.d	sp, t1, 0
@@ -28,11 +29,10 @@ SYM_FUNC_START(handle_syscall) 
	addi.d	sp, sp, -PT_SIZE

	cfi_st	t2, PT_R3

	cfi_rel_offset	sp, PT_R3

	st.d	zero, sp, PT_R0

	csrrd	t2, LOONGARCH_CSR_PRMD

	st.d	t2, sp, PT_PRMD

	cfi_st	ra, PT_R1

	cfi_st	a0, PT_R4

	cfi_st	a0, PT_ORIG_A0

	cfi_st	a1, PT_R5

	cfi_st	a2, PT_R6

	cfi_st	a3, PT_R7
@@ -41,6 +41,7 @@ SYM_FUNC_START(handle_syscall) 
	cfi_st	a6, PT_R10

	cfi_st	a7, PT_R11

	csrrd	ra, LOONGARCH_CSR_ERA

	addi.d	ra, ra, 4

	st.d	ra, sp, PT_ERA

	cfi_rel_offset	ra, PT_ERA
@@ -55,9 +56,17 @@ SYM_FUNC_START(handle_syscall) 
	and	tp, tp, sp



	move	a0, sp

	move	a1, a7

	bl	do_syscall



	RESTORE_ALL_AND_RET

	addi.w	t0, zero, __NR_rt_sigreturn

	bne	a0, t0, 1f



	RESTORE_STATIC

	RESTORE_TEMP

1:

	RESTORE_SOME

	RESTORE_SP_AND_RET

SYM_FUNC_END(handle_syscall)



SYM_CODE_START(ret_from_fork)

arch/loongarch/kernel/syscall.c

+5 −5
Original line number Diff line number Diff line
@@ -37,18 +37,16 @@ void *sys_call_table[__NR_syscalls] = { 
typedef long (*sys_call_fn)(unsigned long, unsigned long,

	unsigned long, unsigned long, unsigned long, unsigned long);



void noinstr do_syscall(struct pt_regs *regs)

unsigned long noinstr do_syscall(struct pt_regs *regs, unsigned long nr)

{

	unsigned long nr;

	sys_call_fn syscall_fn;



	nr = regs->regs[11];

	/* Set for syscall restarting */

	if (nr < NR_syscalls)

		regs->regs[0] = nr + 1;

	else

		regs->regs[0] = 0;



	regs->csr_era += 4;

	regs->orig_a0 = regs->regs[4];

	regs->regs[4] = -ENOSYS;



	nr = syscall_enter_from_user_mode(regs, nr);
@@ -60,4 +58,6 @@ void noinstr do_syscall(struct pt_regs *regs) 
	}



	syscall_exit_to_user_mode(regs);



	return nr;

}