diff options
Diffstat (limited to 'usr/src/uts/intel/dtrace/fasttrap_isa.c')
| -rw-r--r-- | usr/src/uts/intel/dtrace/fasttrap_isa.c | 67 |
1 files changed, 55 insertions, 12 deletions
diff --git a/usr/src/uts/intel/dtrace/fasttrap_isa.c b/usr/src/uts/intel/dtrace/fasttrap_isa.c index bf2ab2f6c6..4be5fab23e 100644 --- a/usr/src/uts/intel/dtrace/fasttrap_isa.c +++ b/usr/src/uts/intel/dtrace/fasttrap_isa.c @@ -2,9 +2,8 @@ * CDDL HEADER START * * The contents of this file are subject to the terms of the - * Common Development and Distribution License, Version 1.0 only - * (the "License"). You may not use this file except in compliance - * with the License. + * Common Development and Distribution License (the "License"). + * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. @@ -19,8 +18,9 @@ * * CDDL HEADER END */ + /* - * Copyright 2005 Sun Microsystems, Inc. All rights reserved. + * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ @@ -41,10 +41,10 @@ * Lossless User-Land Tracing on x86 * --------------------------------- * - * Most instructions' execution is not dependent on their address; for these - * instrutions it is sufficient to copy them into the user process's address - * space and execute them. To effectively single-step an instruction in - * user-land, we copy out the following sequence of instructions to scratch + * The execution of most instructions is not dependent on the address; for + * these instructions it is sufficient to copy them into the user process's + * address space and execute them. To effectively single-step an instruction + * in user-land, we copy out the following sequence of instructions to scratch * space in the user thread's ulwp_t structure. * * We then set the program counter (%eip or %rip) to point to this scratch @@ -222,8 +222,8 @@ fasttrap_anarg(struct regs *rp, int function_entry, int argno) /*ARGSUSED*/ int -fasttrap_tracepoint_init(proc_t *p, fasttrap_probe_t *probe, - fasttrap_tracepoint_t *tp, uintptr_t pc) +fasttrap_tracepoint_init(proc_t *p, fasttrap_tracepoint_t *tp, uintptr_t pc, + fasttrap_probe_type_t type) { uint8_t instr[FASTTRAP_MAX_INSTR_SIZE + 10]; size_t len = FASTTRAP_MAX_INSTR_SIZE; @@ -737,6 +737,7 @@ fasttrap_pid_probe(struct regs *rp) fasttrap_tracepoint_t *tp, tp_local; pid_t pid; dtrace_icookie_t cookie; + uint_t is_enabled = 0; /* * It's possible that a user (in a veritable orgy of bad planning) @@ -809,7 +810,7 @@ fasttrap_pid_probe(struct regs *rp) for (id = tp->ftt_ids; id != NULL; id = id->fti_next) { fasttrap_probe_t *probe = id->fti_probe; - if (probe->ftp_type == DTFTP_ENTRY) { + if (id->fti_ptype == DTFTP_ENTRY) { /* * We note that this was an entry * probe to help ustack() find the @@ -822,6 +823,15 @@ fasttrap_pid_probe(struct regs *rp) rp->r_r8); DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_ENTRY); dtrace_interrupt_enable(cookie); + } else if (id->fti_ptype == DTFTP_IS_ENABLED) { + /* + * Note that in this case, we don't + * call dtrace_probe() since it's only + * an artificial probe meant to change + * the flow of control so that it + * encounters the true probe. + */ + is_enabled = 1; } else if (probe->ftp_argmap == NULL) { dtrace_probe(probe->ftp_id, rp->r_rdi, rp->r_rsi, rp->r_rdx, rp->r_rcx, @@ -858,7 +868,7 @@ fasttrap_pid_probe(struct regs *rp) for (id = tp->ftt_ids; id != NULL; id = id->fti_next) { fasttrap_probe_t *probe = id->fti_probe; - if (probe->ftp_type == DTFTP_ENTRY) { + if (id->fti_ptype == DTFTP_ENTRY) { /* * We note that this was an entry * probe to help ustack() find the @@ -870,6 +880,15 @@ fasttrap_pid_probe(struct regs *rp) s3, s4, s5); DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_ENTRY); dtrace_interrupt_enable(cookie); + } else if (id->fti_ptype == DTFTP_IS_ENABLED) { + /* + * Note that in this case, we don't + * call dtrace_probe() since it's only + * an artificial probe meant to change + * the flow of control so that it + * encounters the true probe. + */ + is_enabled = 1; } else if (probe->ftp_argmap == NULL) { dtrace_probe(probe->ftp_id, s0, s1, s2, s3, s4); @@ -904,6 +923,29 @@ fasttrap_pid_probe(struct regs *rp) */ rp->r_pc = pc + tp->ftt_size; + /* + * If there's an is-enabled probe connected to this tracepoint it + * means that there was a 'xorl %eax, %eax' or 'xorq %rax, %rax' + * instruction that was placed there by DTrace when the binary was + * linked. As this probe is, in fact, enabled, we need to stuff 1 + * into %eax or %rax. Accordingly, we can bypass all the instruction + * emulation logic since we know the inevitable result. It's possible + * that a user could construct a scenario where the 'is-enabled' + * probe was on some other instruction, but that would be a rather + * exotic way to shoot oneself in the foot. + */ + if (is_enabled) { + rp->r_r0 = 1; + new_pc = rp->r_pc; + goto done; + } + + /* + * We emulate certain types of instructions to ensure correctness + * (in the case of position dependent instructions) or optimize + * common cases. The rest we have the thread execute back in user- + * land. + */ switch (tp->ftt_type) { case FASTTRAP_T_RET: case FASTTRAP_T_RET16: @@ -1393,6 +1435,7 @@ fasttrap_pid_probe(struct regs *rp) panic("fasttrap: mishandled an instruction"); } +done: /* * If there were no return probes when we first found the tracepoint, * we should feel no obligation to honor any return probes that were |