LoongArch: Remove redudant csr save/restore

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

--------------------------------
Signed-off-by: NJun Yi <yijun@loongson.cn>
Change-Id: Ib034b577cbebbbe56e936bf541348db271c2a9db

arch/loongarch/include/asm/stackframe.h

@@ -114,14 +114,6 @@
 	LONG_S	zero, sp, PT_R0
 	csrrd	t0, LOONGARCH_CSR_PRMD
 	LONG_S	t0, sp, PT_PRMD
-	csrrd	t0, LOONGARCH_CSR_CRMD
-	LONG_S	t0, sp, PT_CRMD
-	csrrd	t0, LOONGARCH_CSR_EUEN
-	LONG_S  t0, sp, PT_EUEN
-	csrrd	t0, LOONGARCH_CSR_ECFG
-	LONG_S	t0, sp, PT_ECFG
-	csrrd	t0, LOONGARCH_CSR_ESTAT
-	PTR_S	t0, sp, PT_ESTAT
 	cfi_st	ra, PT_R1, \docfi
 	cfi_st	a0, PT_R4, \docfi
 	cfi_st	a1, PT_R5, \docfi
@@ -140,7 +132,6 @@
 	cfi_st	fp, PT_R22, \docfi
 
 	/* Set thread_info if we're coming from user mode */
-	csrrd	t0, LOONGARCH_CSR_PRMD
 	andi	t0, t0, 0x3	/* extract pplv bit */
 	beqz	t0, 9f
 

arch/loongarch/kernel/entry.S

@@ -31,14 +31,6 @@ SYM_FUNC_START(handle_syscall)
 	st.d	zero, sp, PT_R0
 	csrrd	t2, LOONGARCH_CSR_PRMD
 	st.d	t2, sp, PT_PRMD
-	csrrd	t2, LOONGARCH_CSR_CRMD
-	st.d	t2, sp, PT_CRMD
-	csrrd	t2, LOONGARCH_CSR_EUEN
-	st.d	t2, sp, PT_EUEN
-	csrrd	t2, LOONGARCH_CSR_ECFG
-	st.d	t2, sp, PT_ECFG
-	csrrd	t2, LOONGARCH_CSR_ESTAT
-	st.d	t2, sp, PT_ESTAT
 	cfi_st	ra, PT_R1
 	cfi_st	a0, PT_R4
 	cfi_st	a1, PT_R5

arch/loongarch/kernel/switch.S

@@ -16,9 +16,6 @@
  */
 	.align	5
 SYM_FUNC_START(__switch_to)
-	csrrd	t1, LOONGARCH_CSR_PRMD
-	stptr.d	t1, a0, THREAD_CSRPRMD
-
 	cpu_save_nonscratch a0
 	stptr.d	ra, a0, THREAD_REG01
 	stptr.d a3, a0, THREAD_SCHED_RA
@@ -30,8 +27,5 @@ SYM_FUNC_START(__switch_to)
 	PTR_ADD		t0, t0, tp
 	set_saved_sp	t0, t1, t2
 
-	ldptr.d	t1, a1, THREAD_CSRPRMD
-	csrwr	t1, LOONGARCH_CSR_PRMD
-
 	jr	ra
 SYM_FUNC_END(__switch_to)