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ARM: 9066/1: ftrace: pause/unpause function graph tracer in cpu_suspend()

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[ Upstream commit 8252ca87c7a2111502ee13994956f8c309faad7f ]

Enabling function_graph tracer on ARM causes kernel panic, because the
function graph tracer updates the "return address" of a function in order
to insert a trace callback on function exit, it saves the function's
original return address in a return trace stack, but cpu_suspend() may not
return through the normal return path.

cpu_suspend() will resume directly via the cpu_resume path, but the return
trace stack has been set-up by the subfunctions of cpu_suspend(), which
makes the "return address" inconsistent with cpu_suspend().

This patch refers to Commit de818bd452
("arm64: kernel: pause/unpause function graph tracer in cpu_suspend()"),

fixes the issue by pausing/resuming the function graph tracer on the thread
executing cpu_suspend(), so that the function graph tracer state is kept
consistent across functions that enter power down states and never return
by effectively disabling graph tracer while they are executing.

Signed-off-by: louis.wang <liang26812@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
louis.wang 2021-02-24 13:25:53 +01:00 committed by Greg Kroah-Hartman
parent 3029ef71ab
commit ec324393a6
1 changed files with 18 additions and 1 deletions
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19
arch/arm/kernel/suspend.c
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@ -1,4 +1,5 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/ftrace.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/mm_types.h>
@ -25,6 +26,13 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
if (!idmap_pgd)
return -EINVAL;
/*
* Function graph tracer state gets incosistent when the kernel
* calls functions that never return (aka suspend finishers) hence
* disable graph tracing during their execution.
*/
pause_graph_tracing();
/*
* Provide a temporary page table with an identity mapping for
* the MMU-enable code, required for resuming. On successful
@ -32,6 +40,9 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
* back to the correct page tables.
*/
ret = __cpu_suspend(arg, fn, __mpidr);
unpause_graph_tracing();
if (ret == 0) {
cpu_switch_mm(mm->pgd, mm);
local_flush_bp_all();
@ -45,7 +56,13 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
{
u32 __mpidr = cpu_logical_map(smp_processor_id());
return __cpu_suspend(arg, fn, __mpidr);
int ret;
pause_graph_tracing();
ret = __cpu_suspend(arg, fn, __mpidr);
unpause_graph_tracing();
return ret;
}
#define idmap_pgd NULL
#endif