[PATCH AUTOSEL 5.10 04/34] ARM: 9066/1: ftrace: pause/unpause function graph tracer in cpu_suspend()
From: Sasha Levin <sashal@kernel.org>
Date: 2021-05-12 19:53:00
Also in:
lkml, stable
Subsystem:
arm port, the rest · Maintainers:
Russell King, Linus Torvalds
From: "louis.wang" <redacted>
[ 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 de818bd4522c40ea02a81b387d2fa86f989c9623
("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 <redacted>
Signed-off-by: Russell King <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm/kernel/suspend.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/arch/arm/kernel/suspend.c b/arch/arm/kernel/suspend.c
index 24bd20564be7..43f0a3ebf390 100644
--- a/arch/arm/kernel/suspend.c
+++ b/arch/arm/kernel/suspend.c@@ -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
--
2.30.2
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