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author | 2023-05-01 17:19:53 +0800 | |
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committer | 2023-05-01 17:19:53 +0800 | |
commit | 9cdc3b6a299c6314485bcfb695546c11d35dac4c (patch) | |
tree | 2ede544fd74e92ec4668bf5cdfd17c2f0cad9c60 /arch/mips/kernel/i8253.c | |
parent | LoongArch: ftrace: Implement ftrace_find_callable_addr() to simplify code (diff) | |
download | linux-9cdc3b6a299c6314485bcfb695546c11d35dac4c.tar.gz linux-9cdc3b6a299c6314485bcfb695546c11d35dac4c.tar.bz2 linux-9cdc3b6a299c6314485bcfb695546c11d35dac4c.zip |
LoongArch: ftrace: Add direct call support
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>
Diffstat (limited to 'arch/mips/kernel/i8253.c')
0 files changed, 0 insertions, 0 deletions