38 lines
1.3 KiB
Diff
38 lines
1.3 KiB
Diff
From 0ecf6a9e47d825b7dddfebca738386b809e59a94 Mon Sep 17 00:00:00 2001
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From: Michael Ellerman <mpe@ellerman.id.au>
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Date: Wed, 3 Feb 2021 00:02:06 +1100
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Subject: powerpc/64: Make stack tracing work during very early boot
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If we try to stack trace very early during boot, either due to a
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WARN/BUG or manual dump_stack(), we will oops in
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valid_emergency_stack() when we try to dereference the paca_ptrs
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array.
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The fix is simple, we just return false if paca_ptrs isn't allocated
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yet. The stack pointer definitely isn't part of any emergency stack
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because we haven't allocated any yet.
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Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Link: https://lore.kernel.org/r/20210202130207.1303975-1-mpe@ellerman.id.au
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---
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arch/powerpc/kernel/process.c | 3 +++
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1 file changed, 3 insertions(+)
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diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
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index 8520ed5ae144d..e296440e9d16a 100644
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--- a/arch/powerpc/kernel/process.c
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+++ b/arch/powerpc/kernel/process.c
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@@ -2047,6 +2047,9 @@ static inline int valid_emergency_stack(unsigned long sp, struct task_struct *p,
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unsigned long stack_page;
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unsigned long cpu = task_cpu(p);
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+ if (!paca_ptrs)
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+ return 0;
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+
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stack_page = (unsigned long)paca_ptrs[cpu]->emergency_sp - THREAD_SIZE;
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if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
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return 1;
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--
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cgit 1.2.3-1.el7
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