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authorlouis.wang <liang26812@gmail.com>2021-02-24 13:25:53 +0100
committerRussell King <rmk+kernel@armlinux.org.uk>2021-03-25 11:27:42 +0100
commit8252ca87c7a2111502ee13994956f8c309faad7f (patch)
treef774625967534b6779cf69c4f47bb1a427e57074
parentARM: 9064/1: hw_breakpoint: Do not directly check the event's overflow_handle... (diff)
downloadlinux-8252ca87c7a2111502ee13994956f8c309faad7f.tar.xz
linux-8252ca87c7a2111502ee13994956f8c309faad7f.zip
ARM: 9066/1: ftrace: pause/unpause function graph tracer in cpu_suspend()
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 <liang26812@gmail.com> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
-rw-r--r--arch/arm/kernel/suspend.c19
1 files changed, 18 insertions, 1 deletions
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>
@@ -26,12 +27,22 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
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
* resume (indicated by a zero return code), we need to switch
* 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