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authorMark Rutland <mark.rutland@arm.com>2017-08-01 18:51:15 +0100
committerMark Rutland <mark.rutland@arm.com>2017-08-15 18:36:12 +0100
commit12964443e8d1914010f9269f9f9abc4e122bc6ca (patch)
treed111b3b683530290cc4d65992456b68167916a20 /arch
parentarm64: add basic VMAP_STACK support (diff)
downloadlinux-dev-12964443e8d1914010f9269f9f9abc4e122bc6ca.tar.xz
linux-dev-12964443e8d1914010f9269f9f9abc4e122bc6ca.zip
arm64: add on_accessible_stack()
Both unwind_frame() and dump_backtrace() try to check whether a stack address is sane to access, with very similar logic. Both will need updating in order to handle overflow stacks. Factor out this logic into a helper, so that we can avoid further duplication when we add overflow stacks. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Tested-by: Laura Abbott <labbott@redhat.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com>
Diffstat (limited to '')
-rw-r--r--arch/arm64/include/asm/stacktrace.h16
-rw-r--r--arch/arm64/kernel/stacktrace.c7
-rw-r--r--arch/arm64/kernel/traps.c3
3 files changed, 18 insertions, 8 deletions
diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
index 4c68d8a81988..92ddb6d25cf3 100644
--- a/arch/arm64/include/asm/stacktrace.h
+++ b/arch/arm64/include/asm/stacktrace.h
@@ -57,4 +57,20 @@ static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp)
return (low <= sp && sp < high);
}
+/*
+ * We can only safely access per-cpu stacks from current in a non-preemptible
+ * context.
+ */
+static inline bool on_accessible_stack(struct task_struct *tsk, unsigned long sp)
+{
+ if (on_task_stack(tsk, sp))
+ return true;
+ if (tsk != current || preemptible())
+ return false;
+ if (on_irq_stack(sp))
+ return true;
+
+ return false;
+}
+
#endif /* __ASM_STACKTRACE_H */
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 35588caad9d0..3144584617e7 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -50,12 +50,7 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
if (!tsk)
tsk = current;
- /*
- * Switching between stacks is valid when tracing current and in
- * non-preemptible context.
- */
- if (!(tsk == current && !preemptible() && on_irq_stack(fp)) &&
- !on_task_stack(tsk, fp))
+ if (!on_accessible_stack(tsk, fp))
return -EINVAL;
frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 9633773ca42c..d01c5988354b 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -193,8 +193,7 @@ void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
if (in_entry_text(frame.pc)) {
stack = frame.fp - offsetof(struct pt_regs, stackframe);
- if (on_task_stack(tsk, stack) ||
- (tsk == current && !preemptible() && on_irq_stack(stack)))
+ if (on_accessible_stack(tsk, stack))
dump_mem("", "Exception stack", stack,
stack + sizeof(struct pt_regs));
}