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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Split from ftrace_64.S
*/
#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()/ftrace_regs_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.
*/
.macro ftrace_regs_entry allregs
/* Create a minimal stack frame for representing B */
PPC_STLU r1, -STACK_FRAME_MIN_SIZE(r1)
/* Create our stack frame + pt_regs */
PPC_STLU r1,-SWITCH_FRAME_SIZE(r1)
/* Save all gprs to pt_regs */
SAVE_GPR(0, r1)
SAVE_GPRS(3, 10, r1)
#ifdef CONFIG_PPC64
/* Save the original return address in A's stack frame */
std r0, LRSAVE+SWITCH_FRAME_SIZE+STACK_FRAME_MIN_SIZE(r1)
/* Ok to continue? */
lbz r3, PACA_FTRACE_ENABLED(r13)
cmpdi r3, 0
beq ftrace_no_trace
#endif
.if \allregs == 1
SAVE_GPR(2, r1)
SAVE_GPRS(11, 31, r1)
.else
#ifdef CONFIG_LIVEPATCH_64
SAVE_GPR(14, r1)
#endif
.endif
/* Save previous stack pointer (r1) */
addi r8, r1, SWITCH_FRAME_SIZE+STACK_FRAME_MIN_SIZE
PPC_STL r8, GPR1(r1)
.if \allregs == 1
/* Load special regs for save below */
mfmsr r8
mfctr r9
mfxer r10
mfcr r11
.else
/* Clear MSR to flag as ftrace_caller versus frace_regs_caller */
li r8, 0
.endif
/* Get the _mcount() call site out of LR */
mflr r7
/* Save it as pt_regs->nip */
PPC_STL r7, _NIP(r1)
/* Also save it in B's stackframe header for proper unwind */
PPC_STL r7, LRSAVE+SWITCH_FRAME_SIZE(r1)
/* Save the read LR in pt_regs->link */
PPC_STL r0, _LINK(r1)
#ifdef CONFIG_PPC64
/* Save callee's TOC in the ABI compliant location */
std r2, STK_GOT(r1)
LOAD_PACA_TOC() /* get kernel TOC in r2 */
LOAD_REG_ADDR(r3, function_trace_op)
ld r5,0(r3)
#else
lis r3,function_trace_op@ha
lwz r5,function_trace_op@l(r3)
#endif
#ifdef CONFIG_LIVEPATCH_64
mr r14, r7 /* remember old NIP */
#endif
/* 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 */
PPC_STL r8, _MSR(r1)
.if \allregs == 1
PPC_STL r9, _CTR(r1)
PPC_STL r10, _XER(r1)
PPC_STL r11, _CCR(r1)
.endif
/* Load &pt_regs in r6 for call below */
addi r6, r1, STACK_FRAME_OVERHEAD
.endm
.macro ftrace_regs_exit allregs
/* Load ctr with the possibly modified NIP */
PPC_LL r3, _NIP(r1)
mtctr r3
#ifdef CONFIG_LIVEPATCH_64
cmpd r14, r3 /* has NIP been altered? */
#endif
/* Restore gprs */
.if \allregs == 1
REST_GPRS(2, 31, r1)
.else
REST_GPRS(3, 10, r1)
#ifdef CONFIG_LIVEPATCH_64
REST_GPR(14, r1)
#endif
.endif
/* Restore possibly modified LR */
PPC_LL r0, _LINK(r1)
mtlr r0
#ifdef CONFIG_PPC64
/* Restore callee's TOC */
ld r2, STK_GOT(r1)
#endif
/* Pop our stack frame */
addi r1, r1, SWITCH_FRAME_SIZE+STACK_FRAME_MIN_SIZE
#ifdef CONFIG_LIVEPATCH_64
/* Based on the cmpd above, if the NIP was altered handle livepatch */
bne- livepatch_handler
#endif
bctr /* jump after _mcount site */
.endm
_GLOBAL(ftrace_regs_caller)
ftrace_regs_entry 1
/* ftrace_call(r3, r4, r5, r6) */
.globl ftrace_regs_call
ftrace_regs_call:
bl ftrace_stub
nop
ftrace_regs_exit 1
_GLOBAL(ftrace_caller)
ftrace_regs_entry 0
/* ftrace_call(r3, r4, r5, r6) */
.globl ftrace_call
ftrace_call:
bl ftrace_stub
nop
ftrace_regs_exit 0
_GLOBAL(ftrace_stub)
blr
#ifdef CONFIG_PPC64
ftrace_no_trace:
mflr r3
mtctr r3
REST_GPR(3, r1)
addi r1, r1, SWITCH_FRAME_SIZE+STACK_FRAME_MIN_SIZE
mtlr r0
bctr
#endif
#ifdef CONFIG_LIVEPATCH_64
/*
* 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
*/
livepatch_handler:
ld r12, PACA_THREAD_INFO(r13)
/* 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
bctrl
/*
* 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 r12, PACA_THREAD_INFO(r13)
ld r11, TI_livepatch_sp(r12)
/* Check stack marker hasn't been trashed */
lis r2, STACK_END_MAGIC@h
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 */
ld r12, PACA_THREAD_INFO(r13)
subi r11, r11, 24
std r11, TI_livepatch_sp(r12)
/* Return to original caller of live patched function */
blr
#endif /* CONFIG_LIVEPATCH */
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