diff options
| author | Tiejun Chen <tiejun.chen@windriver.com> | 2012-09-16 23:54:30 +0000 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2012-09-18 15:32:42 +1000 |
| commit | a9c4e541ea9b22944da356f2a9258b4eddcc953b (patch) | |
| tree | 3231ff5c12366200c5f5d48e654415e628a231f0 /arch/powerpc/kernel/entry_64.S | |
| parent | f0d1128fcb919a73941a54f80efab04fa3160dfe (diff) | |
powerpc/kprobe: Complete kprobe and migrate exception frame
We can't emulate stwu since that may corrupt current exception stack.
So we will have to do real store operation in the exception return code.
Firstly we'll allocate a trampoline exception frame below the kprobed
function stack and copy the current exception frame to the trampoline.
Then we can do this real store operation to implement 'stwu', and reroute
the trampoline frame to r1 to complete this exception migration.
Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/entry_64.S')
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index b40e0b4815b..0e931aaffca 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -593,6 +593,41 @@ _GLOBAL(ret_from_except_lite) b .ret_from_except resume_kernel: + /* check current_thread_info, _TIF_EMULATE_STACK_STORE */ + CURRENT_THREAD_INFO(r9, r1) + ld r8,TI_FLAGS(r9) + andis. r8,r8,_TIF_EMULATE_STACK_STORE@h + beq+ 1f + + addi r8,r1,INT_FRAME_SIZE /* Get the kprobed function entry */ + + lwz r3,GPR1(r1) + subi r3,r3,INT_FRAME_SIZE /* dst: Allocate a trampoline exception frame */ + mr r4,r1 /* src: current exception frame */ + mr r1,r3 /* Reroute the trampoline frame to r1 */ + + /* Copy from the original to the trampoline. */ + li r5,INT_FRAME_SIZE/8 /* size: INT_FRAME_SIZE */ + li r6,0 /* start offset: 0 */ + mtctr r5 +2: ldx r0,r6,r4 + stdx r0,r6,r3 + addi r6,r6,8 + bdnz 2b + + /* Do real store operation to complete stwu */ + lwz r5,GPR1(r1) + std r8,0(r5) + + /* Clear _TIF_EMULATE_STACK_STORE flag */ + lis r11,_TIF_EMULATE_STACK_STORE@h + addi r5,r9,TI_FLAGS + ldarx r4,0,r5 + andc r4,r4,r11 + stdcx. r4,0,r5 + bne- 0b +1: + #ifdef CONFIG_PREEMPT /* Check if we need to preempt */ andi. r0,r4,_TIF_NEED_RESCHED |