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riscv/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support

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In walk_stackframe, the pc now receives the address from calling
ftrace_graph_ret_addr instead of manual calculation.

Note that the original calculation,
        pc = frame->ra - 4
is buggy when the instruction at the return address happened to be a
compressed inst. But since it is not a critical part of ftrace, it is
ignored for now to ease the review process.

Cc: Greentime Hu <greentime@andestech.com>
Signed-off-by: Alan Kao <alankao@andestech.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This commit is contained in:
Alan Kao 2018-02-13 13:13:21 +08:00 committed by Palmer Dabbelt
parent aea4c671fb
commit b785ec129b
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2 changed files with 7 additions and 1 deletions
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2
arch/riscv/kernel/ftrace.c
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@ -151,7 +151,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
return;
err = ftrace_push_return_trace(old, self_addr, &trace.depth,
frame_pointer, NULL);
frame_pointer, parent);
if (err == -EBUSY)
return;
*parent = return_hooker;

6
arch/riscv/kernel/stacktrace.c
View File

@ -18,6 +18,7 @@
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/stacktrace.h>
#include <linux/ftrace.h>
#ifdef CONFIG_FRAME_POINTER
@ -63,7 +64,12 @@ static void notrace walk_stackframe(struct task_struct *task,
frame = (struct stackframe *)fp - 1;
sp = fp;
fp = frame->fp;
#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
(unsigned long *)(fp - 8));
#else
pc = frame->ra - 0x4;
#endif
}
}