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330 lines
7.1 KiB
330 lines
7.1 KiB
/* SPDX-License-Identifier: GPL-2.0-or-later */ |
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/* |
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* Split from ftrace_64.S |
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*/ |
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#include <linux/magic.h> |
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#include <asm/ppc_asm.h> |
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#include <asm/asm-offsets.h> |
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#include <asm/ftrace.h> |
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#include <asm/ppc-opcode.h> |
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#include <asm/export.h> |
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#include <asm/thread_info.h> |
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#include <asm/bug.h> |
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#include <asm/ptrace.h> |
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/* |
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* |
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* ftrace_caller()/ftrace_regs_caller() is the function that replaces _mcount() |
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* when ftrace is active. |
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* |
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* We arrive here after a function A calls function B, and we are the trace |
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* function for B. When we enter r1 points to A's stack frame, B has not yet |
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* had a chance to allocate one yet. |
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* |
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* Additionally r2 may point either to the TOC for A, or B, depending on |
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* whether B did a TOC setup sequence before calling us. |
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* |
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* On entry the LR points back to the _mcount() call site, and r0 holds the |
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* saved LR as it was on entry to B, ie. the original return address at the |
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* call site in A. |
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* |
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* Our job is to save the register state into a struct pt_regs (on the stack) |
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* and then arrange for the ftrace function to be called. |
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*/ |
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_GLOBAL(ftrace_regs_caller) |
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/* Save the original return address in A's stack frame */ |
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std r0,LRSAVE(r1) |
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/* Create our stack frame + pt_regs */ |
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stdu r1,-SWITCH_FRAME_SIZE(r1) |
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/* Save all gprs to pt_regs */ |
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SAVE_GPR(0, r1) |
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SAVE_10GPRS(2, r1) |
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/* Ok to continue? */ |
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lbz r3, PACA_FTRACE_ENABLED(r13) |
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cmpdi r3, 0 |
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beq ftrace_no_trace |
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SAVE_10GPRS(12, r1) |
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SAVE_10GPRS(22, r1) |
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/* Save previous stack pointer (r1) */ |
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addi r8, r1, SWITCH_FRAME_SIZE |
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std r8, GPR1(r1) |
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/* Load special regs for save below */ |
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mfmsr r8 |
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mfctr r9 |
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mfxer r10 |
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mfcr r11 |
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/* Get the _mcount() call site out of LR */ |
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mflr r7 |
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/* Save it as pt_regs->nip */ |
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std r7, _NIP(r1) |
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/* Save the read LR in pt_regs->link */ |
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std r0, _LINK(r1) |
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/* Save callee's TOC in the ABI compliant location */ |
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std r2, 24(r1) |
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ld r2,PACATOC(r13) /* get kernel TOC in r2 */ |
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addis r3,r2,function_trace_op@toc@ha |
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addi r3,r3,function_trace_op@toc@l |
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ld r5,0(r3) |
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#ifdef CONFIG_LIVEPATCH |
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mr r14,r7 /* remember old NIP */ |
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#endif |
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/* Calculate ip from nip-4 into r3 for call below */ |
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subi r3, r7, MCOUNT_INSN_SIZE |
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/* Put the original return address in r4 as parent_ip */ |
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mr r4, r0 |
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/* Save special regs */ |
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std r8, _MSR(r1) |
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std r9, _CTR(r1) |
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std r10, _XER(r1) |
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std r11, _CCR(r1) |
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/* Load &pt_regs in r6 for call below */ |
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addi r6, r1 ,STACK_FRAME_OVERHEAD |
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/* ftrace_call(r3, r4, r5, r6) */ |
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.globl ftrace_regs_call |
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ftrace_regs_call: |
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bl ftrace_stub |
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nop |
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/* Load ctr with the possibly modified NIP */ |
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ld r3, _NIP(r1) |
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mtctr r3 |
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#ifdef CONFIG_LIVEPATCH |
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cmpd r14, r3 /* has NIP been altered? */ |
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#endif |
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/* Restore gprs */ |
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REST_GPR(0,r1) |
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REST_10GPRS(2,r1) |
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REST_10GPRS(12,r1) |
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REST_10GPRS(22,r1) |
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/* Restore possibly modified LR */ |
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ld r0, _LINK(r1) |
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mtlr r0 |
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/* Restore callee's TOC */ |
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ld r2, 24(r1) |
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/* Pop our stack frame */ |
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addi r1, r1, SWITCH_FRAME_SIZE |
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#ifdef CONFIG_LIVEPATCH |
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/* Based on the cmpd above, if the NIP was altered handle livepatch */ |
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bne- livepatch_handler |
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#endif |
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ftrace_caller_common: |
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER |
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.globl ftrace_graph_call |
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ftrace_graph_call: |
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b ftrace_graph_stub |
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_GLOBAL(ftrace_graph_stub) |
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#endif |
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bctr /* jump after _mcount site */ |
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_GLOBAL(ftrace_stub) |
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blr |
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ftrace_no_trace: |
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mflr r3 |
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mtctr r3 |
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REST_GPR(3, r1) |
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addi r1, r1, SWITCH_FRAME_SIZE |
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mtlr r0 |
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bctr |
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_GLOBAL(ftrace_caller) |
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/* Save the original return address in A's stack frame */ |
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std r0, LRSAVE(r1) |
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/* Create our stack frame + pt_regs */ |
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stdu r1, -SWITCH_FRAME_SIZE(r1) |
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/* Save all gprs to pt_regs */ |
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SAVE_8GPRS(3, r1) |
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lbz r3, PACA_FTRACE_ENABLED(r13) |
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cmpdi r3, 0 |
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beq ftrace_no_trace |
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/* Get the _mcount() call site out of LR */ |
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mflr r7 |
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std r7, _NIP(r1) |
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/* Save callee's TOC in the ABI compliant location */ |
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std r2, 24(r1) |
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ld r2, PACATOC(r13) /* get kernel TOC in r2 */ |
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addis r3, r2, function_trace_op@toc@ha |
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addi r3, r3, function_trace_op@toc@l |
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ld r5, 0(r3) |
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/* Calculate ip from nip-4 into r3 for call below */ |
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subi r3, r7, MCOUNT_INSN_SIZE |
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/* Put the original return address in r4 as parent_ip */ |
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mr r4, r0 |
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/* Set pt_regs to NULL */ |
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li r6, 0 |
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/* ftrace_call(r3, r4, r5, r6) */ |
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.globl ftrace_call |
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ftrace_call: |
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bl ftrace_stub |
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nop |
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ld r3, _NIP(r1) |
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mtctr r3 |
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/* Restore gprs */ |
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REST_8GPRS(3,r1) |
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/* Restore callee's TOC */ |
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ld r2, 24(r1) |
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/* Pop our stack frame */ |
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addi r1, r1, SWITCH_FRAME_SIZE |
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/* Reload original LR */ |
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ld r0, LRSAVE(r1) |
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mtlr r0 |
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/* Handle function_graph or go back */ |
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b ftrace_caller_common |
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#ifdef CONFIG_LIVEPATCH |
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/* |
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* This function runs in the mcount context, between two functions. As |
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* such it can only clobber registers which are volatile and used in |
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* function linkage. |
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* |
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* We get here when a function A, calls another function B, but B has |
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* been live patched with a new function C. |
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* |
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* On entry: |
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* - we have no stack frame and can not allocate one |
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* - LR points back to the original caller (in A) |
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* - CTR holds the new NIP in C |
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* - r0, r11 & r12 are free |
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*/ |
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livepatch_handler: |
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ld r12, PACA_THREAD_INFO(r13) |
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/* Allocate 3 x 8 bytes */ |
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ld r11, TI_livepatch_sp(r12) |
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addi r11, r11, 24 |
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std r11, TI_livepatch_sp(r12) |
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/* Save toc & real LR on livepatch stack */ |
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std r2, -24(r11) |
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mflr r12 |
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std r12, -16(r11) |
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/* Store stack end marker */ |
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lis r12, STACK_END_MAGIC@h |
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ori r12, r12, STACK_END_MAGIC@l |
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std r12, -8(r11) |
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/* Put ctr in r12 for global entry and branch there */ |
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mfctr r12 |
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bctrl |
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/* |
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* Now we are returning from the patched function to the original |
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* caller A. We are free to use r11, r12 and we can use r2 until we |
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* restore it. |
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*/ |
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ld r12, PACA_THREAD_INFO(r13) |
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ld r11, TI_livepatch_sp(r12) |
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/* Check stack marker hasn't been trashed */ |
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lis r2, STACK_END_MAGIC@h |
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ori r2, r2, STACK_END_MAGIC@l |
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ld r12, -8(r11) |
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1: tdne r12, r2 |
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EMIT_BUG_ENTRY 1b, __FILE__, __LINE__ - 1, 0 |
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/* Restore LR & toc from livepatch stack */ |
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ld r12, -16(r11) |
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mtlr r12 |
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ld r2, -24(r11) |
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/* Pop livepatch stack frame */ |
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ld r12, PACA_THREAD_INFO(r13) |
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subi r11, r11, 24 |
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std r11, TI_livepatch_sp(r12) |
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/* Return to original caller of live patched function */ |
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blr |
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#endif /* CONFIG_LIVEPATCH */ |
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER |
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_GLOBAL(ftrace_graph_caller) |
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stdu r1, -112(r1) |
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/* with -mprofile-kernel, parameter regs are still alive at _mcount */ |
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std r10, 104(r1) |
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std r9, 96(r1) |
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std r8, 88(r1) |
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std r7, 80(r1) |
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std r6, 72(r1) |
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std r5, 64(r1) |
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std r4, 56(r1) |
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std r3, 48(r1) |
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/* Save callee's TOC in the ABI compliant location */ |
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std r2, 24(r1) |
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ld r2, PACATOC(r13) /* get kernel TOC in r2 */ |
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addi r5, r1, 112 |
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mfctr r4 /* ftrace_caller has moved local addr here */ |
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std r4, 40(r1) |
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mflr r3 /* ftrace_caller has restored LR from stack */ |
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subi r4, r4, MCOUNT_INSN_SIZE |
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bl prepare_ftrace_return |
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nop |
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/* |
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* prepare_ftrace_return gives us the address we divert to. |
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* Change the LR to this. |
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*/ |
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mtlr r3 |
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ld r0, 40(r1) |
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mtctr r0 |
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ld r10, 104(r1) |
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ld r9, 96(r1) |
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ld r8, 88(r1) |
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ld r7, 80(r1) |
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ld r6, 72(r1) |
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ld r5, 64(r1) |
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ld r4, 56(r1) |
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ld r3, 48(r1) |
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/* Restore callee's TOC */ |
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ld r2, 24(r1) |
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addi r1, r1, 112 |
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mflr r0 |
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std r0, LRSAVE(r1) |
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bctr |
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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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