x86_64: Allow breakpoints to emulate call instructions

In order to allow breakpoints to emulate call instructions, they need to push
the return address onto the stack. The x86_64 int3 handler adds a small gap
to allow the stack to grow some. Use this gap to add the return address to
be able to emulate a call instruction at the breakpoint location.

These helper functions are added:

  int3_emulate_jmp(): changes the location of the regs->ip to return there.

 (The next two are only for x86_64)
  int3_emulate_push(): to push the address onto the gap in the stack
  int3_emulate_call(): push the return address and change regs->ip

Cc: Andy Lutomirski <[email protected]>
Cc: Nicolai Stange <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: the arch/x86 maintainers <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Miroslav Benes <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Joe Lawrence <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Tim Chen <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Mimi Zohar <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Nayna Jain <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: "open list:KERNEL SELFTEST FRAMEWORK" <[email protected]>
Cc: [email protected]
Fixes: b700e7f03df5 ("livepatch: kernel: add support for live patching")
Tested-by: Nicolai Stange <[email protected]>
Reviewed-by: Nicolai Stange <[email protected]>
Reviewed-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
[ Modified to only work for x86_64 and added comment to int3_emulate_push() ]
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

0 files changed, 0 insertions, 0 deletions