[PATCH] powerpc/64: system call implement the bulk of the logic in C fix 2 (tabort_syscall)

[Nicholas Piggin]

Another incremental patch which fixes silly tabort_syscall bug that
causes kernel crashes when making system calls in transactional state.

Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
 arch/powerpc/kernel/entry_64.S   | 9 +++------
 arch/powerpc/kernel/syscall_64.c | 4 ++--
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index d0bb238805e6..94b3db203ec3 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -165,16 +165,13 @@ syscall_restore_regs:
        b       .Lsyscall_restore_regs_cont
 
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
-_GLOBAL(tabort_syscall)
+_GLOBAL(tabort_syscall) /* (unsigned long nip, unsigned long msr) */
        /* Firstly we need to enable TM in the kernel */
        mfmsr   r10
        li      r9, 1
        rldimi  r10, r9, MSR_TM_LG, 63-MSR_TM_LG
        mtmsrd  r10, 0
 
-       ld      r11,_NIP(r13)
-       ld      r12,_MSR(r13)
-
        /* tabort, this dooms the transaction, nothing else */
        li      r9, (TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT)
        TABORT(R9)
@@ -188,8 +185,8 @@ _GLOBAL(tabort_syscall)
        li      r9, MSR_RI
        andc    r10, r10, r9
        mtmsrd  r10, 1
-       mtspr   SPRN_SRR0, r11
-       mtspr   SPRN_SRR1, r12
+       mtspr   SPRN_SRR0, r3
+       mtspr   SPRN_SRR1, r4
        RFI_TO_USER
        b       .       /* prevent speculative execution */
 #endif
diff --git a/arch/powerpc/kernel/syscall_64.c b/arch/powerpc/kernel/syscall_64.c
index cfe458adde07..69a4ef13973b 100644
--- a/arch/powerpc/kernel/syscall_64.c
+++ b/arch/powerpc/kernel/syscall_64.c
@@ -15,7 +15,7 @@
 #include <asm/time.h>
 #include <asm/unistd.h>
 
-extern void __noreturn tabort_syscall(void);
+extern void __noreturn tabort_syscall(unsigned long nip, unsigned long msr);
 
 typedef long (*syscall_fn)(long, long, long, long, long, long);
 
@@ -30,7 +30,7 @@ notrace long system_call_exception(long r3, long r4, long r5, 
long r6, long r7,
 
        if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) &&
            unlikely(regs->msr & MSR_TS_T))
-               tabort_syscall();
+               tabort_syscall(regs->nip, regs->msr);
 
        account_cpu_user_entry();
 
-- 
2.23.0