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MIPS: Fix kernel hang under FUNCTION_GRAPH_TRACER and PREEMPT_TRACER 

[ Upstream commit 78cf0eb926cb1abeff2106bae67752e032fe5f3e ]

When update the latest mainline kernel with the following three configs,
the kernel hangs during startup:

(1) CONFIG_FUNCTION_GRAPH_TRACER=y
(2) CONFIG_PREEMPT_TRACER=y
(3) CONFIG_FTRACE_STARTUP_TEST=y

When update the latest mainline kernel with the above two configs (1)
and (2), the kernel starts normally, but it still hangs when execute
the following command:

echo "function_graph" > /sys/kernel/debug/tracing/current_tracer

Without CONFIG_PREEMPT_TRACER=y, the above two kinds of kernel hangs
disappeared, so it seems that CONFIG_PREEMPT_TRACER has some influences
with function_graph tracer at the first glance.

I use ejtag to find out the epc address is related with preempt_enable()
in the file arch/mips/lib/mips-atomic.c, because function tracing can
trace the preempt_{enable,disable} calls that are traced, replace them
with preempt_{enable,disable}_notrace to prevent function tracing from
going into an infinite loop, and then it can fix the kernel hang issue.

By the way, it seems that this commit is a complement and improvement of
commit f93a1a00f2 ("MIPS: Fix crash that occurs when function tracing
is enabled").

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Tiezhu Yang 2021-05-15 19:02:01 +08:00 committed by Greg Kroah-Hartman
parent eb5c4794b7
commit a450b5b6c0
1 changed files with 6 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
arch/mips/lib/mips-atomic.c
View File

@ -37,7 +37,7 @@
*/
notrace void arch_local_irq_disable(void)
{
preempt_disable();
preempt_disable_notrace();
__asm__ __volatile__(
" .set push \n"
@ -53,7 +53,7 @@ notrace void arch_local_irq_disable(void)
: /* no inputs */
: "memory");
preempt_enable();
preempt_enable_notrace();
}
EXPORT_SYMBOL(arch_local_irq_disable);
@ -61,7 +61,7 @@ notrace unsigned long arch_local_irq_save(void)
{
unsigned long flags;
preempt_disable();
preempt_disable_notrace();
__asm__ __volatile__(
" .set push \n"
@ -78,7 +78,7 @@ notrace unsigned long arch_local_irq_save(void)
: /* no inputs */
: "memory");
preempt_enable();
preempt_enable_notrace();
return flags;
}
@ -88,7 +88,7 @@ notrace void arch_local_irq_restore(unsigned long flags)
{
unsigned long __tmp1;
preempt_disable();
preempt_disable_notrace();
__asm__ __volatile__(
" .set push \n"
@ -106,7 +106,7 @@ notrace void arch_local_irq_restore(unsigned long flags)
: "0" (flags)
: "memory");
preempt_enable();
preempt_enable_notrace();
}
EXPORT_SYMBOL(arch_local_irq_restore);