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-rw-r--r--arch/powerpc/kernel/entry_64.S8
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index e6d52845854..e0bcf935428 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -57,12 +57,18 @@ system_call_common:
beq- 1f
ld r1,PACAKSAVE(r13)
1: std r10,0(r1)
- crclr so
std r11,_NIP(r1)
std r12,_MSR(r1)
std r0,GPR0(r1)
std r10,GPR1(r1)
ACCOUNT_CPU_USER_ENTRY(r10, r11)
+ /*
+ * This "crclr so" clears CR0.SO, which is the error indication on
+ * return from this system call. There must be no cmp instruction
+ * between it and the "mfcr r9" below, otherwise if XER.SO is set,
+ * CR0.SO will get set, causing all system calls to appear to fail.
+ */
+ crclr so
std r2,GPR2(r1)
std r3,GPR3(r1)
std r4,GPR4(r1)