| /* |
| * 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> |
| |
| #ifdef CONFIG_DYNAMIC_FTRACE |
| /* |
| * |
| * 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. |
| */ |
| _GLOBAL(ftrace_caller) |
| /* 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) |
| |
| #ifdef CONFIG_LIVEPATCH |
| 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 */ |
| std r8, _MSR(r1) |
| std r9, _CTR(r1) |
| std r10, _XER(r1) |
| std r11, _CCR(r1) |
| |
| /* Load &pt_regs in r6 for call below */ |
| addi r6, r1 ,STACK_FRAME_OVERHEAD |
| |
| /* ftrace_call(r3, r4, r5, r6) */ |
| .globl ftrace_call |
| ftrace_call: |
| bl ftrace_stub |
| nop |
| |
| /* Load the possibly modified NIP */ |
| ld r15, _NIP(r1) |
| |
| #ifdef CONFIG_LIVEPATCH |
| cmpd r14, r15 /* has NIP been altered? */ |
| #endif |
| |
| #if defined(CONFIG_LIVEPATCH) && defined(CONFIG_KPROBES_ON_FTRACE) |
| /* 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 |
| nop |
| |
| /* |
| * 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 |
| 1: |
| #endif |
| |
| /* Load CTR with the possibly modified NIP */ |
| mtctr r15 |
| |
| /* Restore gprs */ |
| REST_GPR(0,r1) |
| REST_10GPRS(2,r1) |
| REST_10GPRS(12,r1) |
| REST_10GPRS(22,r1) |
| |
| /* 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 |
| |
| #ifdef CONFIG_LIVEPATCH |
| /* |
| * 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 |
| #endif |
| |
| #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
| .globl ftrace_graph_call |
| ftrace_graph_call: |
| b ftrace_graph_stub |
| _GLOBAL(ftrace_graph_stub) |
| #endif |
| |
| bctr /* jump after _mcount site */ |
| |
| _GLOBAL(ftrace_stub) |
| blr |
| |
| #ifdef CONFIG_LIVEPATCH |
| /* |
| * 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: |
| CURRENT_THREAD_INFO(r12, r1) |
| |
| /* 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. |
| */ |
| |
| CURRENT_THREAD_INFO(r12, r1) |
| |
| 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 */ |
| CURRENT_THREAD_INFO(r12, r1) |
| subi r11, r11, 24 |
| std r11, TI_livepatch_sp(r12) |
| |
| /* Return to original caller of live patched function */ |
| blr |
| #endif /* CONFIG_LIVEPATCH */ |
| |
| #endif /* CONFIG_DYNAMIC_FTRACE */ |
| |
| #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
| _GLOBAL(ftrace_graph_caller) |
| 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 |
| nop |
| |
| /* |
| * 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) |
| bctr |
| #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |
