Searched hist:de818bd4522c40ea02a81b387d2fa86f989c9623 (Results 1 – 2 of 2) sorted by relevance
| /openbmc/linux/arch/arm/kernel/ |
| H A D | suspend.c | diff 8252ca87c7a2111502ee13994956f8c309faad7f Wed Feb 24 06:25:53 CST 2021 louis.wang <liang26812@gmail.com> 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>
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| /openbmc/linux/arch/arm64/kernel/ |
| H A D | suspend.c | diff de818bd4522c40ea02a81b387d2fa86f989c9623 Tue Nov 17 05:50:51 CST 2015 Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> arm64: kernel: pause/unpause function graph tracer in cpu_suspend()
The function graph tracer adds instrumentation that is required to trace
both entry and exit of a function. In particular the function graph
tracer updates the "return address" of a function in order to insert
a trace callback on function exit.
Kernel power management functions like cpu_suspend() are called
upon power down entry with functions called "finishers" that are in turn
called to trigger the power down sequence but they may not return to the
kernel through the normal return path.
When the core resumes from low-power it returns to the cpu_suspend()
function through the cpu_resume path, which leaves the trace stack frame
set-up by the function tracer in an incosistent state upon return to the
kernel when tracing is enabled.
This patch fixes the issue by pausing/resuming the function graph
tracer on the thread executing cpu_suspend() (ie the function call that
subsequently triggers the "suspend finishers"), 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.
Fixes: 819e50e25d0c ("arm64: Add ftrace support")
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reported-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: <stable@vger.kernel.org> # 3.16+
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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