Le 24/05/2020 à 11:38, Aneesh Kumar K.V a écrit :
With Hard Lockup watchdog, we can hit a BUG() if we take a watchdog
interrupt when in OPAL mode. This happens in show_instructions()
where the kernel takes the watchdog NMI IPI with MSR_IR == 0.
With that show_instructions() updates the variable pc in the loop
and the second iterations will result in BUG().
We hit the BUG_ON due the below check in __va()
#define __va(x)
\
({ \
VIRTUAL_BUG_ON((unsigned long)(x) >= PAGE_OFFSET); \
(void *)(unsigned long)((phys_addr_t)(x) | PAGE_OFFSET); \
})
Fixes: 4dd7554a6456 ("powerpc/64: Add VIRTUAL_BUG_ON checks for __va and __pa
addresses")
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
If still relevant, this series needs rebase.
Patch 1 was applied with changes, at least patch 3 won't apply
Thanks
Christophe
---
arch/powerpc/kernel/process.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 048d64c4e115..93bf4a766707 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1253,29 +1253,32 @@ struct task_struct *__switch_to(struct task_struct
*prev,
static void show_instructions(struct pt_regs *regs)
{
int i;
+ unsigned long nip = regs->nip;
unsigned long pc = regs->nip - (NR_INSN_TO_PRINT * 3 / 4 * sizeof(int));
printk("Instruction dump:");
+#if !defined(CONFIG_BOOKE)
+ /* If executing with the IMMU off, adjust pc rather
+ * than print XXXXXXXX.
+ */
+ if (!(regs->msr & MSR_IR)) {
+ pc = (unsigned long)phys_to_virt(pc);
+ nip = (unsigned long)phys_to_virt(regs->nip);
+ }
+#endif
+
for (i = 0; i < NR_INSN_TO_PRINT; i++) {
int instr;
if (!(i % 8))
pr_cont("\n");
-#if !defined(CONFIG_BOOKE)
- /* If executing with the IMMU off, adjust pc rather
- * than print XXXXXXXX.
- */
- if (!(regs->msr & MSR_IR))
- pc = (unsigned long)phys_to_virt(pc);
-#endif
-
if (!__kernel_text_address(pc) ||
probe_kernel_address((const void *)pc, instr)) {
pr_cont("XXXXXXXX ");
} else {
- if (regs->nip == pc)
+ if (nip == pc)
pr_cont("<%08x> ", instr);
else
pr_cont("%08x ", instr);
