/* * Code for replacing ftrace calls with jumps. * * Copyright (C) 2007-2008 Steven Rostedt * * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box. * * Added function graph tracer code, taken from x86 that was written * by Frederic Weisbecker, and ported to PPC by Steven Rostedt. * */ #define pr_fmt(fmt) "ftrace-powerpc: " fmt #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_DYNAMIC_FTRACE static unsigned int ftrace_call_replace(unsigned long ip, unsigned long addr, int link) { unsigned int op; addr = ppc_function_entry((void *)addr); /* if (link) set op to 'bl' else 'b' */ op = create_branch((unsigned int *)ip, addr, link ? 1 : 0); return op; } static int ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new) { unsigned int replaced; /* * Note: Due to modules and __init, code can * disappear and change, we need to protect against faulting * as well as code changing. We do this by using the * probe_kernel_* functions. * * No real locking needed, this code is run through * kstop_machine, or before SMP starts. */ /* read the text we want to modify */ if (probe_kernel_read(&replaced, (void *)ip, MCOUNT_INSN_SIZE)) return -EFAULT; /* Make sure it is what we expect it to be */ if (replaced != old) { pr_err("%p: replaced (%#x) != old (%#x)", (void *)ip, replaced, old); return -EINVAL; } /* replace the text with the new text */ if (patch_instruction((unsigned int *)ip, new)) return -EPERM; return 0; } /* * Helper functions that are the same for both PPC64 and PPC32. */ static int test_24bit_addr(unsigned long ip, unsigned long addr) { addr = ppc_function_entry((void *)addr); /* use the create_branch to verify that this offset can be branched */ return create_branch((unsigned int *)ip, addr, 0); } #ifdef CONFIG_MODULES static int is_bl_op(unsigned int op) { return (op & 0xfc000003) == 0x48000001; } static unsigned long find_bl_target(unsigned long ip, unsigned int op) { static int offset; offset = (op & 0x03fffffc); /* make it signed */ if (offset & 0x02000000) offset |= 0xfe000000; return ip + (long)offset; } #ifdef CONFIG_PPC64 static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { unsigned long entry, ptr, tramp; unsigned long ip = rec->ip; unsigned int op, pop; /* 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); pr_devel("ip:%lx jumps to %lx", ip, 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; } /* * Our original call site looks like: * * bl * ld r2,XX(r1) * * Milton Miller pointed out that we can not simply nop the branch. * If a task was preempted when calling a trace function, the nops * will remove the way to restore the TOC in r2 and the r2 TOC will * get corrupted. * * Use a b +8 to jump over the load. */ pop = PPC_INST_BRANCH | 8; /* b +8 */ /* * Check what is in the next instruction. We can see ld r2,40(r1), but * on first pass after boot we will see mflr r0. */ if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) { pr_err("Fetching op failed.\n"); return -EFAULT; } if (op != PPC_INST_LD_TOC) { unsigned int inst; if (probe_kernel_read(&inst, (void *)(ip - 4), 4)) { pr_err("Fetching instruction at %lx failed.\n", ip - 4); return -EFAULT; } /* We expect either a mlfr r0, or a std r0, LRSAVE(r1) */ if (inst != PPC_INST_MFLR && inst != PPC_INST_STD_LR) { pr_err("Unexpected instructions around bl _mcount\n" "when enabling dynamic ftrace!\t" "(%08x,bl,%08x)\n", inst, op); return -EINVAL; } /* When using -mkernel_profile there is no load to jump over */ pop = PPC_INST_NOP; } if (patch_instruction((unsigned int *)ip, pop)) { pr_err("Patching NOP failed.\n"); return -EPERM; } return 0; } #else /* !PPC64 */ static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { unsigned int op; unsigned int jmp[4]; unsigned long ip = rec->ip; unsigned long tramp; if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE)) 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); /* * On PPC32 the trampoline looks like: * 0x3d, 0x80, 0x00, 0x00 lis r12,sym@ha * 0x39, 0x8c, 0x00, 0x00 addi r12,r12,sym@l * 0x7d, 0x89, 0x03, 0xa6 mtctr r12 * 0x4e, 0x80, 0x04, 0x20 bctr */ pr_devel("ip:%lx jumps to %lx", ip, tramp); /* Find where the trampoline jumps to */ if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) { pr_err("Failed to read %lx\n", tramp); return -EFAULT; } pr_devel(" %08x %08x ", jmp[0], jmp[1]); /* verify that this is what we expect it to be */ if (((jmp[0] & 0xffff0000) != 0x3d800000) || ((jmp[1] & 0xffff0000) != 0x398c0000) || (jmp[2] != 0x7d8903a6) || (jmp[3] != 0x4e800420)) { pr_err("Not a trampoline\n"); return -EINVAL; } tramp = (jmp[1] & 0xffff) | ((jmp[0] & 0xffff) << 16); if (tramp & 0x8000) tramp -= 0x10000; pr_devel(" %lx ", tramp); if (tramp != addr) { pr_err("Trampoline location %08lx does not match addr\n", tramp); return -EINVAL; } op = PPC_INST_NOP; if (patch_instruction((unsigned int *)ip, op)) return -EPERM; return 0; } #endif /* PPC64 */ #endif /* CONFIG_MODULES */ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, 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)) { /* within range */ old = ftrace_call_replace(ip, addr, 1); new = PPC_INST_NOP; return ftrace_modify_code(ip, old, new); } #ifdef CONFIG_MODULES /* * Out of range jumps are called from modules. * We should either already have a pointer to the module * or it has been passed in. */ if (!rec->arch.mod) { if (!mod) { pr_err("No module loaded addr=%lx\n", addr); return -EFAULT; } rec->arch.mod = mod; } else if (mod) { if (mod != rec->arch.mod) { pr_err("Record mod %p not equal to passed in mod %p\n", rec->arch.mod, mod); return -EINVAL; } /* nothing to do if mod == rec->arch.mod */ } else mod = rec->arch.mod; return __ftrace_make_nop(mod, rec, addr); #else /* We should not get here without modules */ return -EINVAL; #endif /* CONFIG_MODULES */ } #ifdef CONFIG_MODULES #ifdef CONFIG_PPC64 /* * Examine the existing instructions for __ftrace_make_call. * They should effectively be a NOP, and follow formal constraints, * depending on the ABI. Return false if they don't. */ #ifndef CC_USING_MPROFILE_KERNEL static int expected_nop_sequence(void *ip, unsigned int op0, unsigned int op1) { /* * We expect to see: * * b +8 * ld r2,XX(r1) * * The load offset is different depending on the ABI. For simplicity * just mask it out when doing the compare. */ if ((op0 != 0x48000008) || ((op1 & 0xffff0000) != 0xe8410000)) return 0; return 1; } #else static int expected_nop_sequence(void *ip, unsigned int op0, unsigned int op1) { /* look for patched "NOP" on ppc64 with -mprofile-kernel */ if (op0 != PPC_INST_NOP) return 0; return 1; } #endif static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { unsigned int op[2]; void *ip = (void *)rec->ip; /* read where this goes */ if (probe_kernel_read(op, ip, sizeof(op))) return -EFAULT; if (!expected_nop_sequence(ip, op[0], op[1])) { pr_err("Unexpected call sequence at %p: %x %x\n", ip, op[0], op[1]); return -EINVAL; } /* If we never set up a trampoline to ftrace_caller, then bail */ if (!rec->arch.mod->arch.tramp) { pr_err("No ftrace trampoline\n"); return -EINVAL; } /* Ensure branch is within 24 bits */ if (!create_branch(ip, rec->arch.mod->arch.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)) { pr_err("REL24 out of range!\n"); return -EINVAL; } 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) { unsigned int op; unsigned long ip = rec->ip; /* read where this goes */ if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE)) return -EFAULT; /* It should be pointing to a nop */ if (op != PPC_INST_NOP) { pr_err("Expected NOP but have %x\n", op); return -EINVAL; } /* If we never set up a trampoline to ftrace_caller, then bail */ if (!rec->arch.mod->arch.tramp) { pr_err("No ftrace trampoline\n"); return -EINVAL; } /* create the branch to the trampoline */ op = create_branch((unsigned int *)ip, rec->arch.mod->arch.tramp, BRANCH_SET_LINK); if (!op) { pr_err("REL24 out of range!\n"); return -EINVAL; } pr_devel("write to %lx\n", rec->ip); if (patch_instruction((unsigned int *)ip, op)) return -EPERM; return 0; } #endif /* CONFIG_PPC64 */ #endif /* CONFIG_MODULES */ int ftrace_make_call(struct dyn_ftrace *rec, 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)) { /* within range */ old = PPC_INST_NOP; 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. * Being that we are converting from nop, it had better * already have a module defined. */ if (!rec->arch.mod) { pr_err("No module loaded\n"); return -EINVAL; } return __ftrace_make_call(rec, addr); #else /* We should not get here without modules */ return -EINVAL; #endif /* CONFIG_MODULES */ } int ftrace_update_ftrace_func(ftrace_func_t func) { unsigned long ip = (unsigned long)(&ftrace_call); unsigned int old, new; int ret; old = *(unsigned int *)&ftrace_call; new = ftrace_call_replace(ip, (unsigned long)func, 1); ret = ftrace_modify_code(ip, old, new); return ret; } static int __ftrace_replace_code(struct dyn_ftrace *rec, int enable) { unsigned long ftrace_addr = (unsigned long)FTRACE_ADDR; int ret; ret = ftrace_update_record(rec, enable); switch (ret) { case FTRACE_UPDATE_IGNORE: return 0; case FTRACE_UPDATE_MAKE_CALL: return ftrace_make_call(rec, ftrace_addr); case FTRACE_UPDATE_MAKE_NOP: return ftrace_make_nop(NULL, rec, ftrace_addr); } return 0; } void ftrace_replace_code(int enable) { struct ftrace_rec_iter *iter; struct dyn_ftrace *rec; int ret; for (iter = ftrace_rec_iter_start(); iter; iter = ftrace_rec_iter_next(iter)) { rec = ftrace_rec_iter_record(iter); ret = __ftrace_replace_code(rec, enable); if (ret) { ftrace_bug(ret, rec); return; } } } /* * Use the default ftrace_modify_all_code, but without * stop_machine(). */ void arch_ftrace_update_code(int command) { ftrace_modify_all_code(command); } int __init ftrace_dyn_arch_init(void) { return 0; } #endif /* CONFIG_DYNAMIC_FTRACE */ #ifdef CONFIG_FUNCTION_GRAPH_TRACER #ifdef CONFIG_DYNAMIC_FTRACE extern void ftrace_graph_call(void); extern void ftrace_graph_stub(void); int ftrace_enable_ftrace_graph_caller(void) { unsigned long ip = (unsigned long)(&ftrace_graph_call); unsigned long addr = (unsigned long)(&ftrace_graph_caller); unsigned long stub = (unsigned long)(&ftrace_graph_stub); unsigned int old, new; old = ftrace_call_replace(ip, stub, 0); new = ftrace_call_replace(ip, addr, 0); return ftrace_modify_code(ip, old, new); } int ftrace_disable_ftrace_graph_caller(void) { unsigned long ip = (unsigned long)(&ftrace_graph_call); unsigned long addr = (unsigned long)(&ftrace_graph_caller); unsigned long stub = (unsigned long)(&ftrace_graph_stub); unsigned int old, new; old = ftrace_call_replace(ip, addr, 0); new = ftrace_call_replace(ip, stub, 0); return ftrace_modify_code(ip, old, new); } #endif /* CONFIG_DYNAMIC_FTRACE */ /* * Hook the return address and push it in the stack of return addrs * in current thread info. Return the address we want to divert to. */ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip) { struct ftrace_graph_ent trace; unsigned long return_hooker; if (unlikely(ftrace_graph_is_dead())) goto out; if (unlikely(atomic_read(¤t->tracing_graph_pause))) goto out; return_hooker = ppc_function_entry(return_to_handler); trace.func = ip; trace.depth = current->curr_ret_stack + 1; /* Only trace if the calling function expects to */ if (!ftrace_graph_entry(&trace)) goto out; if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY) goto out; parent = return_hooker; out: return parent; } #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ #if defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_PPC64) unsigned long __init arch_syscall_addr(int nr) { return sys_call_table[nr*2]; } #endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_PPC64 */ #ifdef PPC64_ELF_ABI_v1 char *arch_ftrace_match_adjust(char *str, const char *search) { if (str[0] == '.' && search[0] != '.') return str + 1; else return str; } #endif /* PPC64_ELF_ABI_v1 */