/* SPDX-License-Identifier: GPL-2.0-or-later */ /* * Split from ftrace_64.S */ #include #include #include #include #include #include #include #include #include /* * * 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 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 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 */