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Message-ID: <d7409df92b315e950f7837f7f86614c46360842a.1724153301.git.christophe.leroy@csgroup.eu>
Date: Tue, 20 Aug 2024 13:29:30 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Michael Ellerman <mpe@...erman.id.au>,
Nicholas Piggin <npiggin@...il.com>,
Naveen N Rao <naveen@...nel.org>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
linux-kernel@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/32: Implement validation of emergency stack
VMAP stack added an emergency stack on powerpc/32 for when there is
a stack overflow, but failed to add stack validation for that
emergency stack. That validation is required for show stack.
Implement it.
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
arch/powerpc/include/asm/thread_info.h | 4 ++++
arch/powerpc/kernel/process.c | 20 ++++++++++++++++++--
2 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 15c5691dd218..d2f356e57387 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -226,6 +226,10 @@ static inline int arch_within_stack_frames(const void * const stack,
return BAD_STACK;
}
+#ifdef CONFIG_VMAP_STACK
+extern void *emergency_ctx[];
+#endif
+
#endif /* !__ASSEMBLY__ */
#endif /* __KERNEL__ */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3b506d4c55f3..b27e2f69930c 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -2177,10 +2177,10 @@ static inline int valid_irq_stack(unsigned long sp, struct task_struct *p,
return 0;
}
+#ifdef CONFIG_PPC64
static inline int valid_emergency_stack(unsigned long sp, struct task_struct *p,
unsigned long nbytes)
{
-#ifdef CONFIG_PPC64
unsigned long stack_page;
unsigned long cpu = task_cpu(p);
@@ -2208,10 +2208,26 @@ static inline int valid_emergency_stack(unsigned long sp, struct task_struct *p,
if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;
# endif
-#endif
return 0;
}
+#else
+static inline int valid_emergency_stack(unsigned long sp, struct task_struct *p,
+ unsigned long nbytes)
+{
+ unsigned long stack_page;
+ unsigned long cpu = task_cpu(p);
+
+ if (!IS_ENABLED(CONFIG_VMAP_STACK))
+ return 0;
+
+ stack_page = (unsigned long)emergency_ctx[cpu] - THREAD_SIZE;
+ if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
+ return 1;
+
+ return 0;
+}
+#endif
/*
* validate the stack frame of a particular minimum size, used for when we are
--
2.44.0
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