void-packages/srcpkgs/linux5.10/patches/ppc-stack-traces-early-boot.patch

37 lines
1.3 KiB
Diff

From 0ecf6a9e47d825b7dddfebca738386b809e59a94 Mon Sep 17 00:00:00 2001
From: Michael Ellerman <mpe@ellerman.id.au>
Date: Wed, 3 Feb 2021 00:02:06 +1100
Subject: powerpc/64: Make stack tracing work during very early boot
If we try to stack trace very early during boot, either due to a
WARN/BUG or manual dump_stack(), we will oops in
valid_emergency_stack() when we try to dereference the paca_ptrs
array.
The fix is simple, we just return false if paca_ptrs isn't allocated
yet. The stack pointer definitely isn't part of any emergency stack
because we haven't allocated any yet.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210202130207.1303975-1-mpe@ellerman.id.au
---
arch/powerpc/kernel/process.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 8520ed5ae144d..e296440e9d16a 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -2047,6 +2047,9 @@ static inline int valid_emergency_stack(unsigned long sp, struct task_struct *p,
unsigned long stack_page;
unsigned long cpu = task_cpu(p);
+ if (!paca_ptrs)
+ return 0;
+
stack_page = (unsigned long)paca_ptrs[cpu]->emergency_sp - THREAD_SIZE;
if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;
--
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