From: Mahesh Salgaonkar mahesh@linux.vnet.ibm.com
During Machine Check interrupt on pseries platform, register r3 points RTAS extended event log passed by hypervisor. Since hypervisor uses r3 to pass pointer to rtas log, it stores the original r3 value at the start of the memory (first 8 bytes) pointed by r3. Since hypervisor stores this info and rtas log is in BE format, linux should make sure to restore r3 value in correct endian format.
Without this patch when MCE handler, after recovery, returns to code that that caused the MCE may end up with Data SLB access interrupt for invalid address followed by kernel panic or hang.
[ 62.878965] Severe Machine check interrupt [Recovered] [ 62.878968] NIP [d00000000ca301b8]: init_module+0x1b8/0x338 [bork_kernel] [ 62.878969] Initiator: CPU [ 62.878970] Error type: SLB [Multihit] [ 62.878971] Effective address: d00000000ca70000 cpu 0xa: Vector: 380 (Data SLB Access) at [c0000000fc7775b0] pc: c0000000009694c0: vsnprintf+0x80/0x480 lr: c0000000009698e0: vscnprintf+0x20/0x60 sp: c0000000fc777830 msr: 8000000002009033 dar: a803a30c000000d0 current = 0xc00000000bc9ef00 paca = 0xc00000001eca5c00 softe: 3 irq_happened: 0x01 pid = 8860, comm = insmod [c0000000fc7778b0] c0000000009698e0 vscnprintf+0x20/0x60 [c0000000fc7778e0] c00000000016b6c4 vprintk_emit+0xb4/0x4b0 [c0000000fc777960] c00000000016d40c vprintk_func+0x5c/0xd0 [c0000000fc777980] c00000000016cbb4 printk+0x38/0x4c [c0000000fc7779a0] d00000000ca301c0 init_module+0x1c0/0x338 [bork_kernel] [c0000000fc777a40] c00000000000d9c4 do_one_initcall+0x54/0x230 [c0000000fc777b00] c0000000001b3b74 do_init_module+0x8c/0x248 [c0000000fc777b90] c0000000001b2478 load_module+0x12b8/0x15b0 [c0000000fc777d30] c0000000001b29e8 sys_finit_module+0xa8/0x110 [c0000000fc777e30] c00000000000b204 system_call+0x58/0x6c --- Exception: c00 (System Call) at 00007fff8bda0644 SP (7fffdfbfe980) is in userspace
This patch fixes this issue.
Fixes: a08a53ea4c97 ("powerpc/le: Enable RTAS events support") Cc: stable@vger.kernel.org Reviewed-by: Nicholas Piggin npiggin@gmail.com Signed-off-by: Mahesh Salgaonkar mahesh@linux.vnet.ibm.com --- arch/powerpc/platforms/pseries/ras.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c index f6ba9a2a4f84..e3bd849141de 100644 --- a/arch/powerpc/platforms/pseries/ras.c +++ b/arch/powerpc/platforms/pseries/ras.c @@ -362,7 +362,7 @@ static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs) }
savep = __va(regs->gpr[3]); - regs->gpr[3] = savep[0]; /* restore original r3 */ + regs->gpr[3] = be64_to_cpu(savep[0]); /* restore original r3 */
h = (struct rtas_error_log *)&savep[1]; /* Use the per cpu buffer from paca to store rtas error log */