kpatch/kmod/trampoline.S
Josh Poimboeuf 4feb144e98 It's alive...
The end-to-end patching works.  From object analysis to generation to
runtime patching.  It's still missing the scripting piece that will only
take a patch and kernel source dir as input.
2013-01-16 11:28:59 -06:00

68 lines
1.5 KiB
ArmAsm

#include <linux/linkage.h>
#include <asm/calling.h>
GLOBAL(kpatch_trampoline)
pushq %rcx
pushq %rdi
callq kpatch_ftrace_hacks
leaq kpatch_funcs, %r10
/*
* TODO: if preemption is possible then we'll need to think about how
* to ensure atomic access to the array and how to ensure activeness
* safety here. if preemption is enabled then we need to make sure the
* IP isn't inside kpatch_trampoline for any task.
*/
/* TODO: save/restore flags? */
/* find new function in func_list */
popq %rdi
loop:
movq (%r10), %r9
cmpq %r9, %rdi
je found
/*
* Check for the rare case where we don't have a new function to call.
* This can happen in the small window of time during patch module
* insmod after it has called register_ftrace_function() but before it
* has called stop_machine() to do the activeness safety check and the
* array update. In this case we just return and let the old function
* run.
*/
cmpq $0, %r9
je bail
addq $40, %r10 /* FIXME http://docs.blackfin.uclinux.org/doku.php?id=toolchain:gas:structs */
jmp loop
found:
/* get new function address */
movq 8(%r10), %r10
/* restore regs owned by original calling function */
popq %rax
movq RBP(%rax), %rbp
movq RBX(%rax), %rbx
movq R12(%rax), %r12
movq R13(%rax), %r13
movq R14(%rax), %r14
movq R15(%rax), %r15
/* restore arg registers and stack for new function */
movq RDI(%rax), %rdi
movq RSI(%rax), %rsi
movq RDX(%rax), %rdx
movq RCX(%rax), %rcx
movq RSP(%rax), %rsp
/* jump to new function */
jmpq *%r10
bail:
ret