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x86/kprobes: Get rid of kretprobe_trampoline_holder()

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The kretprobe_trampoline_holder() wrapper around kretprobe_trampoline()
isn't used anywhere and adds some unnecessary frame pointer instructions
which never execute.  Instead, just make kretprobe_trampoline() a proper
ELF function.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/92d921b102fb865a7c254cfde9e4a0a72b9a781e.1453405861.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf 2016-01-21 16:49:28 -06:00 committed by Ingo Molnar
parent d21001cc15
commit c1c355ce14
1 changed files with 28 additions and 29 deletions
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57
arch/x86/kernel/kprobes/core.c
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@ -671,38 +671,37 @@ NOKPROBE_SYMBOL(kprobe_int3_handler);
* When a retprobed function returns, this code saves registers and
* calls trampoline_handler() runs, which calls the kretprobe's handler.
*/
static void __used kretprobe_trampoline_holder(void)
{
asm volatile (
".global kretprobe_trampoline\n"
"kretprobe_trampoline: \n"
asm(
".global kretprobe_trampoline\n"
".type kretprobe_trampoline, @function\n"
"kretprobe_trampoline:\n"
#ifdef CONFIG_X86_64
/* We don't bother saving the ss register */
" pushq %rsp\n"
" pushfq\n"
SAVE_REGS_STRING
" movq %rsp, %rdi\n"
" call trampoline_handler\n"
/* Replace saved sp with true return address. */
" movq %rax, 152(%rsp)\n"
RESTORE_REGS_STRING
" popfq\n"
/* We don't bother saving the ss register */
" pushq %rsp\n"
" pushfq\n"
SAVE_REGS_STRING
" movq %rsp, %rdi\n"
" call trampoline_handler\n"
/* Replace saved sp with true return address. */
" movq %rax, 152(%rsp)\n"
RESTORE_REGS_STRING
" popfq\n"
#else
" pushf\n"
SAVE_REGS_STRING
" movl %esp, %eax\n"
" call trampoline_handler\n"
/* Move flags to cs */
" movl 56(%esp), %edx\n"
" movl %edx, 52(%esp)\n"
/* Replace saved flags with true return address. */
" movl %eax, 56(%esp)\n"
RESTORE_REGS_STRING
" popf\n"
" pushf\n"
SAVE_REGS_STRING
" movl %esp, %eax\n"
" call trampoline_handler\n"
/* Move flags to cs */
" movl 56(%esp), %edx\n"
" movl %edx, 52(%esp)\n"
/* Replace saved flags with true return address. */
" movl %eax, 56(%esp)\n"
RESTORE_REGS_STRING
" popf\n"
#endif
" ret\n");
}
NOKPROBE_SYMBOL(kretprobe_trampoline_holder);
" ret\n"
".size kretprobe_trampoline, .-kretprobe_trampoline\n"
);
NOKPROBE_SYMBOL(kretprobe_trampoline);
/*