[RFC PATCH v1 23/41] powerpc/32: Always save non volatile registers on exception entry

[Christophe Leroy]

In preparation of handling exception entry and exit in C,
in order to simplify the handling, always save non volatile registers
when entering an exception.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
 arch/powerpc/include/asm/ptrace.h | 13 ++++---------
 arch/powerpc/kernel/entry_32.S    | 13 +------------
 arch/powerpc/kernel/head_32.h     |  3 +--
 arch/powerpc/kernel/head_booke.h  |  2 +-
 4 files changed, 7 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index 2c842b11a924..979bd0d4d371 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -194,7 +194,6 @@ static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
 #define FULL_REGS(regs)		(((regs)->trap & 1) == 0)
 #define SET_FULL_REGS(regs)	((regs)->trap |= 1)
 #endif
-#define CHECK_FULL_REGS(regs)	BUG_ON(!FULL_REGS(regs))
 #define NV_REG_POISON		0xdeadbeefdeadbeefUL
 #else
 /*
@@ -204,20 +203,16 @@ static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
  * On 4xx we use the next bit to indicate whether the exception
  * is a critical exception (1 means it is).
  */
-#define TRAP_FLAGS_MASK		0x1F
+#define TRAP_FLAGS_MASK		0x1e
 #define TRAP(regs)		((regs)->trap & ~TRAP_FLAGS_MASK)
-#define FULL_REGS(regs)		(((regs)->trap & 1) == 0)
-#define SET_FULL_REGS(regs)	((regs)->trap |= 1)
+#define FULL_REGS(regs)		true
+#define SET_FULL_REGS(regs)	do { } while (0)
 #define IS_CRITICAL_EXC(regs)	(((regs)->trap & 2) != 0)
 #define IS_MCHECK_EXC(regs)	(((regs)->trap & 4) != 0)
 #define IS_DEBUG_EXC(regs)	(((regs)->trap & 8) != 0)
 #define NV_REG_POISON		0xdeadbeef
-#define CHECK_FULL_REGS(regs)						      \
-do {									      \
-	if ((regs)->trap & 1)						      \
-		printk(KERN_CRIT "%s: partial register set\n", __func__); \
-} while (0)
 #endif /* __powerpc64__ */
+#define CHECK_FULL_REGS(regs)	BUG_ON(!FULL_REGS(regs))
 
 static inline void set_trap(struct pt_regs *regs, unsigned long val)
 {
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index e448ee3f5f15..bbce2de4c6a8 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -81,12 +81,12 @@ _ASM_NOKPROBE_SYMBOL(crit_transfer_to_handler)
  */
 	.globl	transfer_to_handler_full
 transfer_to_handler_full:
-	SAVE_NVGPRS(r11)
 _ASM_NOKPROBE_SYMBOL(transfer_to_handler_full)
 	/* fall through */
 
 	.globl	transfer_to_handler
 transfer_to_handler:
+	SAVE_NVGPRS(r11)
 	stw	r2,GPR2(r11)
 	stw	r12,_NIP(r11)
 	stw	r9,_MSR(r11)
@@ -234,10 +234,6 @@ handle_page_fault:
 	bl	do_page_fault
 	cmpwi	r3,0
 	beq+	ret_from_except
-	SAVE_NVGPRS(r1)
-	lwz	r0,_TRAP(r1)
-	clrrwi	r0,r0,1
-	stw	r0,_TRAP(r1)
 	mr	r4,r3		/* err arg for bad_page_fault */
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	__bad_page_fault
@@ -810,13 +806,6 @@ recheck:
 do_user_signal:			/* r10 contains MSR_KERNEL here */
 	ori	r10,r10,MSR_EE
 	mtmsr	r10		/* hard-enable interrupts */
-	/* save r13-r31 in the exception frame, if not already done */
-	lwz	r3,_TRAP(r1)
-	andi.	r0,r3,1
-	beq	2f
-	SAVE_NVGPRS(r1)
-	rlwinm	r3,r3,0,0,30
-	stw	r3,_TRAP(r1)
 2:	addi	r3,r1,STACK_FRAME_OVERHEAD
 	mr	r4,r9
 	bl	do_notify_resume
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index e09585b88ba7..087445e45489 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -198,7 +198,7 @@ _ASM_NOKPROBE_SYMBOL(\name\()_virt)
 			  ret_from_except_full)
 
 #define EXC_XFER_LITE(n, hdlr)		\
-	EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, transfer_to_handler, \
+	EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, transfer_to_handler, \
 			  ret_from_except)
 
 .macro vmap_stack_overflow_exception
@@ -215,7 +215,6 @@ _ASM_NOKPROBE_SYMBOL(\name\()_virt)
 	lwz	r1, emergency_ctx@l(r1)
 	addi	r1, r1, THREAD_SIZE - INT_FRAME_SIZE
 	EXCEPTION_PROLOG_2 vmap_stack_overflow
-	SAVE_NVGPRS(r11)
 	addi	r3, r1, STACK_FRAME_OVERHEAD
 	EXC_XFER_STD(0, stack_overflow_exception)
 .endm
diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h
index 4286f04648f8..c88c1c474381 100644
--- a/arch/powerpc/kernel/head_booke.h
+++ b/arch/powerpc/kernel/head_booke.h
@@ -331,7 +331,7 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
 			  ret_from_except_full)
 
 #define EXC_XFER_LITE(n, hdlr)		\
-	EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, transfer_to_handler, \
+	EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, transfer_to_handler, \
 			  ret_from_except)
 
 /* Check for a single step debug exception while in an exception
-- 
2.25.0