From ae30cc05bed2fd7eb05e4fb53f412783f05ccb7b Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" Date: Thu, 19 Apr 2018 12:34:09 +0530 Subject: [PATCH] powerpc64/ftrace: Implement support for ftrace_regs_caller() With -mprofile-kernel, we always save the full register state in ftrace_caller(). While this works, this is inefficient if we're not interested in the register state, such as when we're using the function tracer. Rename the existing ftrace_caller() as ftrace_regs_caller() and provide a simpler implementation for ftrace_caller() that is used when registers are not required to be saved. Signed-off-by: Naveen N. Rao Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/ftrace.h | 2 - arch/powerpc/include/asm/module.h | 3 + arch/powerpc/kernel/module_64.c | 28 ++- arch/powerpc/kernel/trace/ftrace.c | 184 ++++++++++++++++-- .../powerpc/kernel/trace/ftrace_64_mprofile.S | 71 ++++++- 5 files changed, 262 insertions(+), 26 deletions(-) diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index 3b5e85a72e10..f0806a2fd451 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -49,8 +49,6 @@ extern void _mcount(void); #ifdef CONFIG_DYNAMIC_FTRACE -# define FTRACE_ADDR ((unsigned long)ftrace_caller) -# define FTRACE_REGS_ADDR FTRACE_ADDR static inline unsigned long ftrace_call_adjust(unsigned long addr) { /* reloction of mcount call site is the same as the address */ diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h index 4f6573934792..18f7214d68b7 100644 --- a/arch/powerpc/include/asm/module.h +++ b/arch/powerpc/include/asm/module.h @@ -53,6 +53,9 @@ struct mod_arch_specific { #ifdef CONFIG_DYNAMIC_FTRACE unsigned long toc; unsigned long tramp; +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + unsigned long tramp_regs; +#endif #endif /* For module function descriptor dereference */ diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index 8413be31d6a4..f7667e2ebfcb 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -280,6 +280,10 @@ static unsigned long get_stubs_size(const Elf64_Ehdr *hdr, #ifdef CONFIG_DYNAMIC_FTRACE /* make the trampoline to the ftrace_caller */ relocs++; +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + /* an additional one for ftrace_regs_caller */ + relocs++; +#endif #endif pr_debug("Looks like a total of %lu stubs, max\n", relocs); @@ -765,7 +769,8 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, * via the paca (in r13). The target (ftrace_caller()) is responsible for * saving and restoring the toc before returning. */ -static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me) +static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, + struct module *me, unsigned long addr) { struct ppc64_stub_entry *entry; unsigned int i, num_stubs; @@ -792,9 +797,10 @@ static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module memcpy(entry->jump, stub_insns, sizeof(stub_insns)); /* Stub uses address relative to kernel toc (from the paca) */ - reladdr = (unsigned long)ftrace_caller - kernel_toc_addr(); + reladdr = addr - kernel_toc_addr(); if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { - pr_err("%s: Address of ftrace_caller out of range of kernel_toc.\n", me->name); + pr_err("%s: Address of %ps out of range of kernel_toc.\n", + me->name, (void *)addr); return 0; } @@ -802,22 +808,30 @@ static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module entry->jump[2] |= PPC_LO(reladdr); /* Eventhough we don't use funcdata in the stub, it's needed elsewhere. */ - entry->funcdata = func_desc((unsigned long)ftrace_caller); + entry->funcdata = func_desc(addr); entry->magic = STUB_MAGIC; return (unsigned long)entry; } #else -static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me) +static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, + struct module *me, unsigned long addr) { - return stub_for_addr(sechdrs, (unsigned long)ftrace_caller, me); + return stub_for_addr(sechdrs, addr, me); } #endif int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs) { mod->arch.toc = my_r2(sechdrs, mod); - mod->arch.tramp = create_ftrace_stub(sechdrs, mod); + mod->arch.tramp = create_ftrace_stub(sechdrs, mod, + (unsigned long)ftrace_caller); +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + mod->arch.tramp_regs = create_ftrace_stub(sechdrs, mod, + (unsigned long)ftrace_regs_caller); + if (!mod->arch.tramp_regs) + return -ENOENT; +#endif if (!mod->arch.tramp) return -ENOENT; diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c index 80667128db3d..79d2924e75d5 100644 --- a/arch/powerpc/kernel/trace/ftrace.c +++ b/arch/powerpc/kernel/trace/ftrace.c @@ -357,6 +357,8 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { unsigned int op[2]; void *ip = (void *)rec->ip; + unsigned long entry, ptr, tramp; + struct module *mod = rec->arch.mod; /* read where this goes */ if (probe_kernel_read(op, ip, sizeof(op))) @@ -368,19 +370,44 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) return -EINVAL; } - /* If we never set up a trampoline to ftrace_caller, then bail */ - if (!rec->arch.mod->arch.tramp) { + /* If we never set up ftrace trampoline(s), then bail */ +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + if (!mod->arch.tramp || !mod->arch.tramp_regs) { +#else + if (!mod->arch.tramp) { +#endif pr_err("No ftrace trampoline\n"); return -EINVAL; } +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + if (rec->flags & FTRACE_FL_REGS) + tramp = mod->arch.tramp_regs; + else +#endif + tramp = mod->arch.tramp; + + if (module_trampoline_target(mod, tramp, &ptr)) { + pr_err("Failed to get trampoline target\n"); + return -EFAULT; + } + + pr_devel("trampoline target %lx", ptr); + + entry = ppc_global_function_entry((void *)addr); + /* This should match what was called */ + if (ptr != entry) { + pr_err("addr %lx does not match expected %lx\n", ptr, entry); + return -EINVAL; + } + /* Ensure branch is within 24 bits */ - if (!create_branch(ip, rec->arch.mod->arch.tramp, BRANCH_SET_LINK)) { + if (!create_branch(ip, tramp, BRANCH_SET_LINK)) { pr_err("Branch out of range\n"); return -EINVAL; } - if (patch_branch(ip, rec->arch.mod->arch.tramp, BRANCH_SET_LINK)) { + if (patch_branch(ip, tramp, BRANCH_SET_LINK)) { pr_err("REL24 out of range!\n"); return -EINVAL; } @@ -388,14 +415,6 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) return 0; } -#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS -int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, - unsigned long addr) -{ - return ftrace_make_call(rec, addr); -} -#endif - #else /* !CONFIG_PPC64: */ static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) @@ -472,6 +491,137 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) #endif /* CONFIG_MODULES */ } +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +#ifdef CONFIG_MODULES +static int +__ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + unsigned int op; + unsigned long ip = rec->ip; + unsigned long entry, ptr, tramp; + struct module *mod = rec->arch.mod; + + /* If we never set up ftrace trampolines, then bail */ + if (!mod->arch.tramp || !mod->arch.tramp_regs) { + pr_err("No ftrace trampoline\n"); + return -EINVAL; + } + + /* read where this goes */ + if (probe_kernel_read(&op, (void *)ip, sizeof(int))) { + pr_err("Fetching opcode failed.\n"); + return -EFAULT; + } + + /* Make sure that that this is still a 24bit jump */ + if (!is_bl_op(op)) { + pr_err("Not expected bl: opcode is %x\n", op); + return -EINVAL; + } + + /* lets find where the pointer goes */ + tramp = find_bl_target(ip, op); + entry = ppc_global_function_entry((void *)old_addr); + + pr_devel("ip:%lx jumps to %lx", ip, tramp); + + if (tramp != entry) { + /* old_addr is not within range, so we must have used a trampoline */ + if (module_trampoline_target(mod, tramp, &ptr)) { + pr_err("Failed to get trampoline target\n"); + return -EFAULT; + } + + pr_devel("trampoline target %lx", ptr); + + /* This should match what was called */ + if (ptr != entry) { + pr_err("addr %lx does not match expected %lx\n", ptr, entry); + return -EINVAL; + } + } + + /* The new target may be within range */ + if (test_24bit_addr(ip, addr)) { + /* within range */ + if (patch_branch((unsigned int *)ip, addr, BRANCH_SET_LINK)) { + pr_err("REL24 out of range!\n"); + return -EINVAL; + } + + return 0; + } + + if (rec->flags & FTRACE_FL_REGS) + tramp = mod->arch.tramp_regs; + else + tramp = mod->arch.tramp; + + if (module_trampoline_target(mod, tramp, &ptr)) { + pr_err("Failed to get trampoline target\n"); + return -EFAULT; + } + + pr_devel("trampoline target %lx", ptr); + + entry = ppc_global_function_entry((void *)addr); + /* This should match what was called */ + if (ptr != entry) { + pr_err("addr %lx does not match expected %lx\n", ptr, entry); + return -EINVAL; + } + + /* Ensure branch is within 24 bits */ + if (!create_branch((unsigned int *)ip, tramp, BRANCH_SET_LINK)) { + pr_err("Branch out of range\n"); + return -EINVAL; + } + + if (patch_branch((unsigned int *)ip, tramp, BRANCH_SET_LINK)) { + pr_err("REL24 out of range!\n"); + return -EINVAL; + } + + return 0; +} +#endif + +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + unsigned long ip = rec->ip; + unsigned int old, new; + + /* + * If the calling address is more that 24 bits away, + * then we had to use a trampoline to make the call. + * Otherwise just update the call site. + */ + if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) { + /* within range */ + old = ftrace_call_replace(ip, old_addr, 1); + new = ftrace_call_replace(ip, addr, 1); + return ftrace_modify_code(ip, old, new); + } + +#ifdef CONFIG_MODULES + /* + * Out of range jumps are called from modules. + */ + if (!rec->arch.mod) { + pr_err("No module loaded\n"); + return -EINVAL; + } + + return __ftrace_modify_call(rec, old_addr, addr); +#else + /* We should not get here without modules */ + return -EINVAL; +#endif /* CONFIG_MODULES */ +} +#endif + int ftrace_update_ftrace_func(ftrace_func_t func) { unsigned long ip = (unsigned long)(&ftrace_call); @@ -482,6 +632,16 @@ int ftrace_update_ftrace_func(ftrace_func_t func) new = ftrace_call_replace(ip, (unsigned long)func, 1); ret = ftrace_modify_code(ip, old, new); +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + /* Also update the regs callback function */ + if (!ret) { + ip = (unsigned long)(&ftrace_regs_call); + old = *(unsigned int *)&ftrace_regs_call; + new = ftrace_call_replace(ip, (unsigned long)func, 1); + ret = ftrace_modify_code(ip, old, new); + } +#endif + return ret; } diff --git a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S index ae1cbe783ab6..ed9d7a46c3af 100644 --- a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S +++ b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S @@ -20,8 +20,8 @@ #ifdef CONFIG_DYNAMIC_FTRACE /* * - * ftrace_caller() is the function that replaces _mcount() when ftrace is - * active. + * 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 @@ -37,7 +37,7 @@ * 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) +_GLOBAL(ftrace_regs_caller) /* Save the original return address in A's stack frame */ std r0,LRSAVE(r1) @@ -100,8 +100,8 @@ _GLOBAL(ftrace_caller) addi r6, r1 ,STACK_FRAME_OVERHEAD /* ftrace_call(r3, r4, r5, r6) */ -.globl ftrace_call -ftrace_call: +.globl ftrace_regs_call +ftrace_regs_call: bl ftrace_stub nop @@ -162,6 +162,7 @@ ftrace_call: bne- livepatch_handler #endif +ftrace_caller_common: #ifdef CONFIG_FUNCTION_GRAPH_TRACER .globl ftrace_graph_call ftrace_graph_call: @@ -182,6 +183,66 @@ ftrace_no_trace: mtlr r0 bctr +_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_8GPRS(3, r1) + + lbz r3, PACA_FTRACE_ENABLED(r13) + cmpdi r3, 0 + beq ftrace_no_trace + + /* Get the _mcount() call site out of LR */ + mflr r7 + std r7, _NIP(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) + + /* 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 + + /* Set pt_regs to NULL */ + li r6, 0 + + /* ftrace_call(r3, r4, r5, r6) */ +.globl ftrace_call +ftrace_call: + bl ftrace_stub + nop + + ld r3, _NIP(r1) + mtctr r3 + + /* Restore gprs */ + REST_8GPRS(3,r1) + + /* Restore callee's TOC */ + ld r2, 24(r1) + + /* Pop our stack frame */ + addi r1, r1, SWITCH_FRAME_SIZE + + /* Reload original LR */ + ld r0, LRSAVE(r1) + mtlr r0 + + /* Handle function_graph or go back */ + b ftrace_caller_common + #ifdef CONFIG_LIVEPATCH /* * This function runs in the mcount context, between two functions. As