Author: markj Date: Tue Aug 28 20:21:36 2018 New Revision: 338359 URL: https://svnweb.freebsd.org/changeset/base/338359
Log: Allow multiple FBT probes to share a tracepoint. With GNU ifuncs, multiple FBT probes may correspond to the same instruction. fbt_invop() assumed that this could not happen and would return after the first probe found in the global FBT hash table, which might not be the one that's enabled. Fix the problem on x86 by linking probes that share a tracepoint and having each linked probe fire when the tracepoint is hit. PR: 230846 Approved by: re (gjb) Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D16921 Modified: head/sys/cddl/dev/fbt/aarch64/fbt_isa.c head/sys/cddl/dev/fbt/arm/fbt_isa.c head/sys/cddl/dev/fbt/fbt.c head/sys/cddl/dev/fbt/fbt.h head/sys/cddl/dev/fbt/mips/fbt_isa.c head/sys/cddl/dev/fbt/powerpc/fbt_isa.c head/sys/cddl/dev/fbt/riscv/fbt_isa.c head/sys/cddl/dev/fbt/x86/fbt_isa.c Modified: head/sys/cddl/dev/fbt/aarch64/fbt_isa.c ============================================================================== --- head/sys/cddl/dev/fbt/aarch64/fbt_isa.c Tue Aug 28 18:50:34 2018 (r338358) +++ head/sys/cddl/dev/fbt/aarch64/fbt_isa.c Tue Aug 28 20:21:36 2018 (r338359) @@ -152,7 +152,7 @@ again: fbt->fbtp_id = dtrace_probe_create(fbt_id, modname, name, FBT_RETURN, 3, fbt); } else { - retfbt->fbtp_next = fbt; + retfbt->fbtp_probenext = fbt; fbt->fbtp_id = retfbt->fbtp_id; } retfbt = fbt; Modified: head/sys/cddl/dev/fbt/arm/fbt_isa.c ============================================================================== --- head/sys/cddl/dev/fbt/arm/fbt_isa.c Tue Aug 28 18:50:34 2018 (r338358) +++ head/sys/cddl/dev/fbt/arm/fbt_isa.c Tue Aug 28 20:21:36 2018 (r338359) @@ -165,7 +165,7 @@ again: fbt->fbtp_id = dtrace_probe_create(fbt_id, modname, name, FBT_RETURN, 2, fbt); } else { - retfbt->fbtp_next = fbt; + retfbt->fbtp_probenext = fbt; fbt->fbtp_id = retfbt->fbtp_id; } retfbt = fbt; Modified: head/sys/cddl/dev/fbt/fbt.c ============================================================================== --- head/sys/cddl/dev/fbt/fbt.c Tue Aug 28 18:50:34 2018 (r338358) +++ head/sys/cddl/dev/fbt/fbt.c Tue Aug 28 20:21:36 2018 (r338359) @@ -156,7 +156,7 @@ fbt_doubletrap(void) for (i = 0; i < fbt_probetab_size; i++) { fbt = fbt_probetab[i]; - for (; fbt != NULL; fbt = fbt->fbtp_next) + for (; fbt != NULL; fbt = fbt->fbtp_probenext) fbt_patch_tracepoint(fbt, fbt->fbtp_savedval); } } @@ -205,39 +205,52 @@ fbt_provide_module(void *arg, modctl_t *lf) } static void +fbt_destroy_one(fbt_probe_t *fbt) +{ + fbt_probe_t *hash, *hashprev, *next; + int ndx; + + ndx = FBT_ADDR2NDX(fbt->fbtp_patchpoint); + for (hash = fbt_probetab[ndx], hashprev = NULL; hash != NULL; + hash = hash->fbtp_hashnext, hashprev = hash) { + if (hash == fbt) { + if ((next = fbt->fbtp_tracenext) != NULL) + next->fbtp_hashnext = hash->fbtp_hashnext; + else + next = hash->fbtp_hashnext; + if (hashprev != NULL) + hashprev->fbtp_hashnext = next; + else + fbt_probetab[ndx] = next; + goto free; + } else if (hash->fbtp_patchpoint == fbt->fbtp_patchpoint) { + for (next = hash; next->fbtp_tracenext != NULL; + next = next->fbtp_tracenext) { + if (fbt == next->fbtp_tracenext) { + next->fbtp_tracenext = + fbt->fbtp_tracenext; + goto free; + } + } + } + } + panic("probe %p not found in hash table", fbt); +free: + free(fbt, M_FBT); +} + +static void fbt_destroy(void *arg, dtrace_id_t id, void *parg) { - fbt_probe_t *fbt = parg, *next, *hash, *last; + fbt_probe_t *fbt = parg, *next; modctl_t *ctl; - int ndx; do { ctl = fbt->fbtp_ctl; - ctl->fbt_nentries--; - /* - * Now we need to remove this probe from the fbt_probetab. - */ - ndx = FBT_ADDR2NDX(fbt->fbtp_patchpoint); - last = NULL; - hash = fbt_probetab[ndx]; - - while (hash != fbt) { - ASSERT(hash != NULL); - last = hash; - hash = hash->fbtp_hashnext; - } - - if (last != NULL) { - last->fbtp_hashnext = fbt->fbtp_hashnext; - } else { - fbt_probetab[ndx] = fbt->fbtp_hashnext; - } - - next = fbt->fbtp_next; - free(fbt, M_FBT); - + next = fbt->fbtp_probenext; + fbt_destroy_one(fbt); fbt = next; } while (fbt != NULL); } @@ -265,14 +278,16 @@ fbt_enable(void *arg, dtrace_id_t id, void *parg) return; } - for (; fbt != NULL; fbt = fbt->fbtp_next) + for (; fbt != NULL; fbt = fbt->fbtp_probenext) { fbt_patch_tracepoint(fbt, fbt->fbtp_patchval); + fbt->fbtp_enabled++; + } } static void fbt_disable(void *arg, dtrace_id_t id, void *parg) { - fbt_probe_t *fbt = parg; + fbt_probe_t *fbt = parg, *hash; modctl_t *ctl = fbt->fbtp_ctl; ASSERT(ctl->nenabled > 0); @@ -281,8 +296,21 @@ fbt_disable(void *arg, dtrace_id_t id, void *parg) if ((ctl->loadcnt != fbt->fbtp_loadcnt)) return; - for (; fbt != NULL; fbt = fbt->fbtp_next) - fbt_patch_tracepoint(fbt, fbt->fbtp_savedval); + for (; fbt != NULL; fbt = fbt->fbtp_probenext) { + fbt->fbtp_enabled--; + + for (hash = fbt_probetab[FBT_ADDR2NDX(fbt->fbtp_patchpoint)]; + hash != NULL; hash = hash->fbtp_hashnext) { + if (hash->fbtp_patchpoint == fbt->fbtp_patchpoint) { + for (; hash != NULL; hash = hash->fbtp_tracenext) + if (hash->fbtp_enabled > 0) + break; + break; + } + } + if (hash == NULL) + fbt_patch_tracepoint(fbt, fbt->fbtp_savedval); + } } static void @@ -296,7 +324,7 @@ fbt_suspend(void *arg, dtrace_id_t id, void *parg) if ((ctl->loadcnt != fbt->fbtp_loadcnt)) return; - for (; fbt != NULL; fbt = fbt->fbtp_next) + for (; fbt != NULL; fbt = fbt->fbtp_probenext) fbt_patch_tracepoint(fbt, fbt->fbtp_savedval); } @@ -311,7 +339,7 @@ fbt_resume(void *arg, dtrace_id_t id, void *parg) if ((ctl->loadcnt != fbt->fbtp_loadcnt)) return; - for (; fbt != NULL; fbt = fbt->fbtp_next) + for (; fbt != NULL; fbt = fbt->fbtp_probenext) fbt_patch_tracepoint(fbt, fbt->fbtp_patchval); } Modified: head/sys/cddl/dev/fbt/fbt.h ============================================================================== --- head/sys/cddl/dev/fbt/fbt.h Tue Aug 28 18:50:34 2018 (r338358) +++ head/sys/cddl/dev/fbt/fbt.h Tue Aug 28 20:21:36 2018 (r338359) @@ -34,9 +34,18 @@ #include "fbt_isa.h" +/* + * fbt_probe is a bit of a misnomer. One of these structures is created for + * each trace point of an FBT probe. A probe might have multiple trace points + * (e.g., a function with multiple return instructions), and different probes + * might have a trace point at the same address (e.g., GNU ifuncs). + */ typedef struct fbt_probe { - struct fbt_probe *fbtp_hashnext; - fbt_patchval_t *fbtp_patchpoint; + struct fbt_probe *fbtp_hashnext; /* global hash table linkage */ + struct fbt_probe *fbtp_tracenext; /* next probe for tracepoint */ + struct fbt_probe *fbtp_probenext; /* next tracepoint for probe */ + int fbtp_enabled; + fbt_patchval_t *fbtp_patchpoint; int8_t fbtp_rval; fbt_patchval_t fbtp_patchval; fbt_patchval_t fbtp_savedval; @@ -46,7 +55,6 @@ typedef struct fbt_probe { modctl_t *fbtp_ctl; int fbtp_loadcnt; int fbtp_symindx; - struct fbt_probe *fbtp_next; } fbt_probe_t; struct linker_file; Modified: head/sys/cddl/dev/fbt/mips/fbt_isa.c ============================================================================== --- head/sys/cddl/dev/fbt/mips/fbt_isa.c Tue Aug 28 18:50:34 2018 (r338358) +++ head/sys/cddl/dev/fbt/mips/fbt_isa.c Tue Aug 28 20:21:36 2018 (r338359) @@ -142,7 +142,7 @@ again: fbt->fbtp_id = dtrace_probe_create(fbt_id, modname, name, FBT_RETURN, 3, fbt); } else { - retfbt->fbtp_next = fbt; + retfbt->fbtp_probenext = fbt; fbt->fbtp_id = retfbt->fbtp_id; } retfbt = fbt; Modified: head/sys/cddl/dev/fbt/powerpc/fbt_isa.c ============================================================================== --- head/sys/cddl/dev/fbt/powerpc/fbt_isa.c Tue Aug 28 18:50:34 2018 (r338358) +++ head/sys/cddl/dev/fbt/powerpc/fbt_isa.c Tue Aug 28 20:21:36 2018 (r338359) @@ -208,7 +208,7 @@ again: fbt->fbtp_id = dtrace_probe_create(fbt_id, modname, name, FBT_RETURN, FBT_AFRAMES, fbt); } else { - retfbt->fbtp_next = fbt; + retfbt->fbtp_probenext = fbt; fbt->fbtp_id = retfbt->fbtp_id; } Modified: head/sys/cddl/dev/fbt/riscv/fbt_isa.c ============================================================================== --- head/sys/cddl/dev/fbt/riscv/fbt_isa.c Tue Aug 28 18:50:34 2018 (r338358) +++ head/sys/cddl/dev/fbt/riscv/fbt_isa.c Tue Aug 28 20:21:36 2018 (r338359) @@ -141,7 +141,7 @@ again: fbt->fbtp_id = dtrace_probe_create(fbt_id, modname, name, FBT_RETURN, 3, fbt); } else { - retfbt->fbtp_next = fbt; + retfbt->fbtp_probenext = fbt; fbt->fbtp_id = retfbt->fbtp_id; } retfbt = fbt; Modified: head/sys/cddl/dev/fbt/x86/fbt_isa.c ============================================================================== --- head/sys/cddl/dev/fbt/x86/fbt_isa.c Tue Aug 28 18:50:34 2018 (r338358) +++ head/sys/cddl/dev/fbt/x86/fbt_isa.c Tue Aug 28 20:21:36 2018 (r338359) @@ -67,6 +67,7 @@ fbt_invop(uintptr_t addr, struct trapframe *frame, uin uintptr_t *stack; uintptr_t arg0, arg1, arg2, arg3, arg4; fbt_probe_t *fbt; + int8_t fbtrval; #ifdef __amd64__ stack = (uintptr_t *)frame->tf_rsp; @@ -78,7 +79,11 @@ fbt_invop(uintptr_t addr, struct trapframe *frame, uin cpu = &solaris_cpu[curcpu]; fbt = fbt_probetab[FBT_ADDR2NDX(addr)]; for (; fbt != NULL; fbt = fbt->fbtp_hashnext) { - if ((uintptr_t)fbt->fbtp_patchpoint == addr) { + if ((uintptr_t)fbt->fbtp_patchpoint != addr) + continue; + fbtrval = fbt->fbtp_rval; + for (; fbt != NULL; fbt = fbt->fbtp_tracenext) { + ASSERT(fbt->fbtp_rval == fbtrval); if (fbt->fbtp_roffset == 0) { #ifdef __amd64__ /* fbt->fbtp_rval == DTRACE_INVOP_PUSHQ_RBP */ @@ -135,9 +140,8 @@ fbt_invop(uintptr_t addr, struct trapframe *frame, uin rval, 0, 0, 0); cpu->cpu_dtrace_caller = 0; } - - return (fbt->fbtp_rval); } + return (fbtrval); } return (0); @@ -162,7 +166,7 @@ fbt_provide_module_function(linker_file_t lf, int symi { char *modname = opaque; const char *name = symval->name; - fbt_probe_t *fbt, *retfbt; + fbt_probe_t *fbt, *hash, *retfbt; int j; int size; uint8_t *instr, *limit; @@ -224,8 +228,18 @@ fbt_provide_module_function(linker_file_t lf, int symi fbt->fbtp_patchval = FBT_PATCHVAL; fbt->fbtp_symindx = symindx; - fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)]; - fbt_probetab[FBT_ADDR2NDX(instr)] = fbt; + for (hash = fbt_probetab[FBT_ADDR2NDX(instr)]; hash != NULL; + hash = hash->fbtp_hashnext) { + if (hash->fbtp_patchpoint == fbt->fbtp_patchpoint) { + fbt->fbtp_tracenext = hash->fbtp_tracenext; + hash->fbtp_tracenext = fbt; + break; + } + } + if (hash == NULL) { + fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)]; + fbt_probetab[FBT_ADDR2NDX(instr)] = fbt; + } lf->fbt_nentries++; @@ -301,7 +315,7 @@ again: fbt->fbtp_id = dtrace_probe_create(fbt_id, modname, name, FBT_RETURN, 3, fbt); } else { - retfbt->fbtp_next = fbt; + retfbt->fbtp_probenext = fbt; fbt->fbtp_id = retfbt->fbtp_id; } _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "[email protected]"
