x86/ftrace: Implement DYNAMIC_FTRACE_WITH_JMP

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Implement the DYNAMIC_FTRACE_WITH_JMP for x86_64. In ftrace_call_replace,
we will use JMP32_INSN_OPCODE instead of CALL_INSN_OPCODE if the address
should use "jmp".

Meanwhile, adjust the direct call in the ftrace_regs_caller. The RSB is
balanced in the "jmp" mode. Take the function "foo" for example:

 original_caller:
 call foo -> foo:
         call fentry -> fentry:
                 [do ftrace callbacks ]
                 move tramp_addr to stack
                 RET -> tramp_addr
                         tramp_addr:
                         [..]
                         call foo_body -> foo_body:
                                 [..]
                                 RET -> back to tramp_addr
                         [..]
                         RET -> back to original_caller

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20251118123639.688444-3-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

...

This commit is contained in:

Menglong Dong 2025-11-18 20:36:30 +08:00 • committed by Alexei Starovoitov

parent 25e4e3565d

commit 0c3772a8db

3 changed files with 18 additions and 2 deletions

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1

arch/x86/Kconfig

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7

arch/x86/kernel/ftrace.c

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12

arch/x86/kernel/ftrace_64.S

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