powerpc/32: Save remaining registers in exception prolog

Save non volatile registers, XER, CTR, MSR and NIP in exception prolog.

Also assign proper value to r2 and r3 there.

For now, recalculate thread pointer in prepare_transfer_to_handler.
It will disappear once KUAP is ported to C.

And remove the comment which is now completely wrong.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/56f0cde9dd0362edf2ddba4d887552013eee7329.1615552867.git.christophe.leroy@csgroup.eu

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index bcf8452..46b3854 100644 (file)
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -48,29 +48,11 @@
  */
        .align  12
 
-/*
- * This code finishes saving the registers to the exception frame
- * and jumps to the appropriate handler for the exception, turning
- * on address translation.
- * Note that we rely on the caller having set cr0.eq iff the exception
- * occurred in kernel mode (i.e. MSR:PR = 0).
- */
        .globl  prepare_transfer_to_handler
 prepare_transfer_to_handler:
-       SAVE_NVGPRS(r11)
-       addi    r3,r1,STACK_FRAME_OVERHEAD
-       stw     r2,GPR2(r11)
-       stw     r12,_NIP(r11)
-       stw     r9,_MSR(r11)
-       andi.   r2,r9,MSR_PR
-       mfctr   r12
-       mfspr   r2,SPRN_XER
-       stw     r12,_CTR(r11)
-       stw     r2,_XER(r11)
-       mfspr   r12,SPRN_SPRG_THREAD
-       tovirt(r12, r12)
+       andi.   r12,r9,MSR_PR
+       addi    r12,r2,THREAD
        beq     2f
-       addi    r2, r12, -THREAD
 #ifdef CONFIG_PPC_BOOK3S_32
        kuep_lock r11, r12
 #endif
@@ -78,8 +60,7 @@ prepare_transfer_to_handler:
 
        /* if from kernel, check interrupted DOZE/NAP mode */
 2:
-       kuap_save_and_lock r11, r12, r9, r2, r6
-       addi    r2, r12, -THREAD
+       kuap_save_and_lock r11, r12, r9, r5, r6
 #if defined(CONFIG_PPC_BOOK3S_32) || defined(CONFIG_E500)
        lwz     r12,TI_LOCAL_FLAGS(r2)
        mtcrf   0x01,r12
@@ -293,7 +274,7 @@ fast_exception_return:
 
 2:     REST_4GPRS(3, r11)
        lwz     r10,_CCR(r11)
-       REST_GPR(1, r11)
+       REST_2GPRS(1, r11)
        mtcr    r10
        lwz     r10,_LINK(r11)
        mtlr    r10

diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index ba20bfa..80e45c8 100644 (file)
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -117,6 +117,18 @@ _ASM_NOKPROBE_SYMBOL(\name\()_virt)
        stw     r10,_TRAP(r1)
        SAVE_4GPRS(3, r1)
        SAVE_2GPRS(7, r1)
+       SAVE_NVGPRS(r1)
+       stw     r2,GPR2(r1)
+       stw     r12,_NIP(r1)
+       stw     r9,_MSR(r1)
+       mfctr   r10
+       mfspr   r2,SPRN_SPRG_THREAD
+       stw     r10,_CTR(r1)
+       tovirt(r2, r2)
+       mfspr   r10,SPRN_XER
+       addi    r2, r2, -THREAD
+       stw     r10,_XER(r1)
+       addi    r3,r1,STACK_FRAME_OVERHEAD
 .endm
 
 .macro prepare_transfer_to_handler

diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h
index 4d583fb..7f3dd5f 100644 (file)
--- a/arch/powerpc/kernel/head_booke.h
+++ b/arch/powerpc/kernel/head_booke.h
@@ -89,6 +89,18 @@ END_BTB_FLUSH_SECTION
        stw     r10,_TRAP(r1)
        SAVE_4GPRS(3, r1)
        SAVE_2GPRS(7, r1)
+       SAVE_NVGPRS(r1)
+       stw     r2,GPR2(r1)
+       stw     r12,_NIP(r1)
+       stw     r9,_MSR(r1)
+       mfctr   r10
+       mfspr   r2,SPRN_SPRG_THREAD
+       stw     r10,_CTR(r1)
+       tovirt(r2, r2)
+       mfspr   r10,SPRN_XER
+       addi    r2, r2, -THREAD
+       stw     r10,_XER(r1)
+       addi    r3,r1,STACK_FRAME_OVERHEAD
 .endm
 
 .macro prepare_transfer_to_handler