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stackleak: Mark stackleak_track_stack() as notrace
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Function graph tracing recurses into itself when stackleak is enabled,
causing the ftrace graph selftest to run for up to 90 seconds and
trigger the softlockup watchdog.

Breakpoint 2, ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:200
200             mcount_get_lr_addr        x0    //     pointer to function's saved lr
(gdb) bt
\#0  ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:200
\rib#1  0xffffff80081d5280 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:153
\rib#2  0xffffff8008555484 in stackleak_track_stack () at ../kernel/stackleak.c:106
\rib#3  0xffffff8008421ff8 in ftrace_ops_test (ops=0xffffff8009eaa840 <graph_ops>, ip=18446743524091297036, regs=<optimized out>) at ../kernel/trace/ftrace.c:1507
\rib#4  0xffffff8008428770 in __ftrace_ops_list_func (regs=<optimized out>, ignored=<optimized out>, parent_ip=<optimized out>, ip=<optimized out>) at ../kernel/trace/ftrace.c:6286
\rib#5  ftrace_ops_no_ops (ip=18446743524091297036, parent_ip=18446743524091242824) at ../kernel/trace/ftrace.c:6321
\rib#6  0xffffff80081d5280 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:153
\rib#7  0xffffff800832fd10 in irq_find_mapping (domain=0xffffffc03fc4bc80, hwirq=27) at ../kernel/irq/irqdomain.c:876
\rib#8  0xffffff800832294c in __handle_domain_irq (domain=0xffffffc03fc4bc80, hwirq=27, lookup=true, regs=0xffffff800814b840) at ../kernel/irq/irqdesc.c:650
\rib#9  0xffffff80081d52b4 in ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:205

Rework so we mark stackleak_track_stack as notrace

Co-developed-by: Arnd Bergmann <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
Signed-off-by: Anders Roxell <[email protected]>
Acked-by: Steven Rostedt (VMware) <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
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@roxell @kees
roxell authored and kees committed Dec 6, 2018
1 parent ef1a840 commit e9c7d65
Showing 1 changed file with 1 addition and 1 deletion.
2 changes: 1 addition & 1 deletion kernel/stackleak.c
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Original file line number Diff line number Diff line change
Expand Up @@ -104,7 +104,7 @@ asmlinkage void notrace stackleak_erase(void)
}
NOKPROBE_SYMBOL(stackleak_erase);

void __used stackleak_track_stack(void)
void __used notrace stackleak_track_stack(void)
{
/*
* N.B. stackleak_erase() fills the kernel stack with the poison value,
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