diff options
Diffstat (limited to 'arch/powerpc/kernel/trace/ftrace_mprofile.S')
| -rw-r--r-- | arch/powerpc/kernel/trace/ftrace_mprofile.S | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/trace/ftrace_mprofile.S b/arch/powerpc/kernel/trace/ftrace_mprofile.S new file mode 100644 index 000000000..f4a72b384 --- /dev/null +++ b/arch/powerpc/kernel/trace/ftrace_mprofile.S @@ -0,0 +1,256 @@ +/* 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 */ |