blob: b4e2b7165f79b0d45da686ea8fe77da4dca109ca [file] [log] [blame]
* Split from ftrace_64.S
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
#include <linux/magic.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/ftrace.h>
#include <asm/ppc-opcode.h>
#include <asm/export.h>
#include <asm/thread_info.h>
#include <asm/bug.h>
#include <asm/ptrace.h>
* ftrace_caller() is the function that replaces _mcount() when ftrace is
* active.
* We arrive here after a function A calls function B, and we are the trace
* function for B. When we enter r1 points to A's stack frame, B has not yet
* had a chance to allocate one yet.
* Additionally r2 may point either to the TOC for A, or B, depending on
* whether B did a TOC setup sequence before calling us.
* On entry the LR points back to the _mcount() call site, and r0 holds the
* saved LR as it was on entry to B, ie. the original return address at the
* call site in A.
* Our job is to save the register state into a struct pt_regs (on the stack)
* and then arrange for the ftrace function to be called.
/* Save the original return address in A's stack frame */
std r0,LRSAVE(r1)
/* Create our stack frame + pt_regs */
stdu r1,-SWITCH_FRAME_SIZE(r1)
/* Save all gprs to pt_regs */
SAVE_GPR(0, r1)
SAVE_10GPRS(2, r1)
SAVE_10GPRS(12, r1)
SAVE_10GPRS(22, r1)
/* Save previous stack pointer (r1) */
addi r8, r1, SWITCH_FRAME_SIZE
std r8, GPR1(r1)
/* Load special regs for save below */
mfmsr r8
mfctr r9
mfxer r10
mfcr r11
/* Get the _mcount() call site out of LR */
mflr r7
/* Save it as pt_regs->nip */
std r7, _NIP(r1)
/* Save the read LR in pt_regs->link */
std r0, _LINK(r1)
/* Save callee's TOC in the ABI compliant location */
std r2, 24(r1)
ld r2,PACATOC(r13) /* get kernel TOC in r2 */
addis r3,r2,function_trace_op@toc@ha
addi r3,r3,function_trace_op@toc@l
ld r5,0(r3)
mr r14,r7 /* remember old NIP */
/* Calculate ip from nip-4 into r3 for call below */
subi r3, r7, MCOUNT_INSN_SIZE
/* Put the original return address in r4 as parent_ip */
mr r4, r0
/* Save special regs */
std r8, _MSR(r1)
std r9, _CTR(r1)
std r10, _XER(r1)
std r11, _CCR(r1)
/* Load &pt_regs in r6 for call below */
/* ftrace_call(r3, r4, r5, r6) */
.globl ftrace_call
bl ftrace_stub
/* Load the possibly modified NIP */
ld r15, _NIP(r1)
cmpd r14, r15 /* has NIP been altered? */
/* NIP has not been altered, skip over further checks */
beq 1f
/* Check if there is an active kprobe on us */
subi r3, r14, 4
bl is_current_kprobe_addr
* If r3 == 1, then this is a kprobe/jprobe.
* else, this is livepatched function.
* The conditional branch for livepatch_handler below will use the
* result of this comparison. For kprobe/jprobe, we just need to branch to
* the new NIP, not call livepatch_handler. The branch below is bne, so we
* want CR0[EQ] to be true if this is a kprobe/jprobe. Which means we want
* CR0[EQ] = (r3 == 1).
cmpdi r3, 1
/* Load CTR with the possibly modified NIP */
mtctr r15
/* Restore gprs */
/* Restore possibly modified LR */
ld r0, _LINK(r1)
mtlr r0
/* Restore callee's TOC */
ld r2, 24(r1)
/* Pop our stack frame */
addi r1, r1, SWITCH_FRAME_SIZE
* Based on the cmpd or cmpdi above, if the NIP was altered and we're
* not on a kprobe/jprobe, then handle livepatch.
bne- livepatch_handler
.globl ftrace_graph_call
b ftrace_graph_stub
bctr /* jump after _mcount site */
* This function runs in the mcount context, between two functions. As
* such it can only clobber registers which are volatile and used in
* function linkage.
* We get here when a function A, calls another function B, but B has
* been live patched with a new function C.
* On entry:
* - we have no stack frame and can not allocate one
* - LR points back to the original caller (in A)
* - CTR holds the new NIP in C
* - r0, r11 & r12 are free
/* Allocate 3 x 8 bytes */
ld r11, TI_livepatch_sp(r12)
addi r11, r11, 24
std r11, TI_livepatch_sp(r12)
/* Save toc & real LR on livepatch stack */
std r2, -24(r11)
mflr r12
std r12, -16(r11)
/* Store stack end marker */
lis r12, STACK_END_MAGIC@h
ori r12, r12, STACK_END_MAGIC@l
std r12, -8(r11)
/* Put ctr in r12 for global entry and branch there */
mfctr r12
* Now we are returning from the patched function to the original
* caller A. We are free to use r11, r12 and we can use r2 until we
* restore it.
ld r11, TI_livepatch_sp(r12)
/* Check stack marker hasn't been trashed */
ori r2, r2, STACK_END_MAGIC@l
ld r12, -8(r11)
1: tdne r12, r2
EMIT_BUG_ENTRY 1b, __FILE__, __LINE__ - 1, 0
/* Restore LR & toc from livepatch stack */
ld r12, -16(r11)
mtlr r12
ld r2, -24(r11)
/* Pop livepatch stack frame */
subi r11, r11, 24
std r11, TI_livepatch_sp(r12)
/* Return to original caller of live patched function */
stdu r1, -112(r1)
/* with -mprofile-kernel, parameter regs are still alive at _mcount */
std r10, 104(r1)
std r9, 96(r1)
std r8, 88(r1)
std r7, 80(r1)
std r6, 72(r1)
std r5, 64(r1)
std r4, 56(r1)
std r3, 48(r1)
/* Save callee's TOC in the ABI compliant location */
std r2, 24(r1)
ld r2, PACATOC(r13) /* get kernel TOC in r2 */
mfctr r4 /* ftrace_caller has moved local addr here */
std r4, 40(r1)
mflr r3 /* ftrace_caller has restored LR from stack */
subi r4, r4, MCOUNT_INSN_SIZE
bl prepare_ftrace_return
* prepare_ftrace_return gives us the address we divert to.
* Change the LR to this.
mtlr r3
ld r0, 40(r1)
mtctr r0
ld r10, 104(r1)
ld r9, 96(r1)
ld r8, 88(r1)
ld r7, 80(r1)
ld r6, 72(r1)
ld r5, 64(r1)
ld r4, 56(r1)
ld r3, 48(r1)
/* Restore callee's TOC */
ld r2, 24(r1)
addi r1, r1, 112
mflr r0
std r0, LRSAVE(r1)