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Commit c3d6324f authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Alexei Starovoitov
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x86/alternatives: Teach text_poke_bp() to emulate instructions



In preparation for static_call and variable size jump_label support,
teach text_poke_bp() to emulate instructions, namely:

  JMP32, JMP8, CALL, NOP2, NOP_ATOMIC5, INT3

The current text_poke_bp() takes a @handler argument which is used as
a jump target when the temporary INT3 is hit by a different CPU.

When patching CALL instructions, this doesn't work because we'd miss
the PUSH of the return address. Instead, teach poke_int3_handler() to
emulate an instruction, typically the instruction we're patching in.

This fits almost all text_poke_bp() users, except
arch_unoptimize_kprobe() which restores random text, and for that site
we have to build an explicit emulate instruction.

Tested-by: default avatarAlexei Starovoitov <ast@kernel.org>
Tested-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: default avatarDaniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191111132457.529086974@infradead.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
(cherry picked from commit 8c7eebc10687af45ac8e40ad1bac0cf7893dba9f)
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 808c9f7e
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