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authorNicholas Piggin <npiggin@gmail.com>2019-08-02 12:56:39 +0200
committerMichael Ellerman <mpe@ellerman.id.au>2019-08-30 02:32:36 +0200
commitb7d9ccec3056913528690c5fae7cc86a5ea3dffc (patch)
tree335cda249be8efed464efff9d0b005898461ab80 /arch
parentpowerpc/64s/exception: simplify machine check early path (diff)
downloadlinux-b7d9ccec3056913528690c5fae7cc86a5ea3dffc.tar.xz
linux-b7d9ccec3056913528690c5fae7cc86a5ea3dffc.zip
powerpc/64s/exception: machine check move unrecoverable handling out of line
Similarly to the previous change, all callers of the unrecoverable handler run relocated so can reach it with a direct branch. This makes it easy to move out of line, which makes the "normal" path less cluttered and easier to follow. MSR[ME] manipulation still requires the rfi, so that is moved out of line to its own function. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20190802105709.27696-15-npiggin@gmail.com
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/kernel/exceptions-64s.S87
1 files changed, 44 insertions, 43 deletions
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index bbbcab88cf78..af18d0f1d4ab 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -992,9 +992,9 @@ EXC_COMMON_BEGIN(machine_check_early_common)
bne 1f
/* First machine check entry */
ld r1,PACAMCEMERGSP(r13) /* Use MC emergency stack */
-1: subi r1,r1,INT_FRAME_SIZE /* alloc stack frame */
- /* Limit nested MCE to level 4 to avoid stack overflow */
- bge cr1,2f /* Check if we hit limit of 4 */
+1: /* Limit nested MCE to level 4 to avoid stack overflow */
+ bgt cr1,unrecoverable_mce /* Check if we hit limit of 4 */
+ subi r1,r1,INT_FRAME_SIZE /* alloc stack frame */
EXCEPTION_PROLOG_COMMON_1()
/* We don't touch AMR here, we never go to virtual mode */
@@ -1013,21 +1013,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
mtmsrd r10,1
b machine_check_handle_early
-2:
- /* Stack overflow. Stay on emergency stack and panic.
- * Keep the ME bit off while panic-ing, so that if we hit
- * another machine check we checkstop.
- */
- addi r1,r1,INT_FRAME_SIZE /* go back to previous stack frame */
- ld r11,PACAKMSR(r13)
- LOAD_HANDLER(r12, unrecover_mce)
- li r10,MSR_ME
- andc r11,r11,r10 /* Turn off MSR_ME */
- mtspr SPRN_SRR0,r12
- mtspr SPRN_SRR1,r11
- RFI_TO_KERNEL
- b . /* prevent speculative execution */
-
EXC_COMMON_BEGIN(machine_check_common)
/*
* Machine check is different because we use a different
@@ -1141,32 +1126,15 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
* If yes, then stay on emergency stack and panic.
*/
andi. r11,r12,MSR_RI
- bne 2f
-1: mfspr r11,SPRN_SRR0
- LOAD_HANDLER(r10,unrecover_mce)
- mtspr SPRN_SRR0,r10
- ld r10,PACAKMSR(r13)
- /*
- * We are going down. But there are chances that we might get hit by
- * another MCE during panic path and we may run into unstable state
- * with no way out. Hence, turn ME bit off while going down, so that
- * when another MCE is hit during panic path, system will checkstop
- * and hypervisor will get restarted cleanly by SP.
- */
- li r3,MSR_ME
- andc r10,r10,r3 /* Turn off MSR_ME */
- mtspr SPRN_SRR1,r10
- RFI_TO_KERNEL
- b .
-2:
+ beq unrecoverable_mce
+
/*
* Check if we have successfully handled/recovered from error, if not
* then stay on emergency stack and panic.
*/
ld r3,RESULT(r1) /* Load result */
cmpdi r3,0 /* see if we handled MCE successfully */
-
- beq 1b /* if !handled then panic */
+ beq unrecoverable_mce /* if !handled then panic */
/*
* Return from MC interrupt.
@@ -1189,17 +1157,35 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
EXCEPTION_PROLOG_1 EXC_STD, PACA_EXMC, 1, 0x200, 1, 1, 0
EXCEPTION_PROLOG_2_REAL machine_check_common, EXC_STD, 0
-EXC_COMMON_BEGIN(unrecover_mce)
+EXC_COMMON_BEGIN(unrecoverable_mce)
+ /*
+ * We are going down. But there are chances that we might get hit by
+ * another MCE during panic path and we may run into unstable state
+ * with no way out. Hence, turn ME bit off while going down, so that
+ * when another MCE is hit during panic path, system will checkstop
+ * and hypervisor will get restarted cleanly by SP.
+ */
+BEGIN_FTR_SECTION
+ li r10,0 /* clear MSR_RI */
+ mtmsrd r10,1
+ bl disable_machine_check
+END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
+ ld r10,PACAKMSR(r13)
+ li r3,MSR_ME
+ andc r10,r10,r3
+ mtmsrd r10
+
/* Invoke machine_check_exception to print MCE event and panic. */
addi r3,r1,STACK_FRAME_OVERHEAD
bl machine_check_exception
+
/*
- * We will not reach here. Even if we did, there is no way out. Call
- * unrecoverable_exception and die.
+ * We will not reach here. Even if we did, there is no way out.
+ * Call unrecoverable_exception and die.
*/
-1: addi r3,r1,STACK_FRAME_OVERHEAD
+ addi r3,r1,STACK_FRAME_OVERHEAD
bl unrecoverable_exception
- b 1b
+ b .
EXC_REAL_BEGIN(data_access, 0x300, 0x80)
@@ -2282,6 +2268,21 @@ enable_machine_check:
1: mtlr r0
blr
+/* MSR[RI] should be clear because this uses SRR[01] */
+disable_machine_check:
+ mflr r0
+ bcl 20,31,$+4
+0: mflr r3
+ addi r3,r3,(1f - 0b)
+ mtspr SPRN_SRR0,r3
+ mfmsr r3
+ li r4,MSR_ME
+ andc r3,r3,r4
+ mtspr SPRN_SRR1,r3
+ RFI_TO_KERNEL
+1: mtlr r0
+ blr
+
/*
* Hash table stuff
*/