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9cdc3b6a29
Select the HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS to provide the
register_ftrace_direct[_multi] interfaces allowing users to register
the customed trampoline (direct_caller) as the mcount for one or more
target functions. And modify_ftrace_direct[_multi] are also provided
for modifying direct_caller.
There are a few cases to distinguish:
- If a direct call ops is the only one tracing a function AND the direct
called trampoline is within the reach of a 'bl' instruction
-> the ftrace patchsite jumps to the trampoline
- Else
-> the ftrace patchsite jumps to the ftrace_regs_caller trampoline points
to ftrace_list_ops so it iterates over all registered ftrace ops,
including the direct call ops and calls its call_direct_funcs handler
which stores the direct called trampoline's address in the ftrace_regs
and the ftrace_regs_caller trampoline will return to that address
instead of returning to the traced function
Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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| include | ||
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| lib | ||
| mm | ||
| net | ||
| pci | ||
| power | ||
| vdso | ||
| Kbuild | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||