powerpc/32: Always save non volatile registers on exception entry

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@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/3ce8ced87a4f1467fa36fcc50763d53b45e466c1.1615552867.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
index bedbca0..f10498e 100644 (file)
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -209,16 +209,14 @@ static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
  */
 #define TRAP_FLAGS_MASK                0x1F
 #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__ */
 

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index fb849ef..7084289 100644 (file)
--- 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 e09585b..087445e 100644 (file)
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -198,7 +198,7 @@ label:
                          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 @@ vmap_stack_overflow:
        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 3707f49..b31bf9e 100644 (file)
--- a/arch/powerpc/kernel/head_booke.h
+++ b/arch/powerpc/kernel/head_booke.h
@@ -331,7 +331,7 @@ label:
                          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