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
This commit is contained in:
parent
4ec2e460b5
commit
c208cb9923
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=338359
@ -152,7 +152,7 @@ fbt_provide_module_function(linker_file_t lf, int symindx,
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fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
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name, FBT_RETURN, 3, fbt);
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} else {
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retfbt->fbtp_next = fbt;
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retfbt->fbtp_probenext = fbt;
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fbt->fbtp_id = retfbt->fbtp_id;
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}
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retfbt = fbt;
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@ -165,7 +165,7 @@ fbt_provide_module_function(linker_file_t lf, int symindx,
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fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
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name, FBT_RETURN, 2, fbt);
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} else {
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retfbt->fbtp_next = fbt;
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retfbt->fbtp_probenext = fbt;
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fbt->fbtp_id = retfbt->fbtp_id;
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}
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retfbt = fbt;
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@ -156,7 +156,7 @@ fbt_doubletrap(void)
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for (i = 0; i < fbt_probetab_size; i++) {
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fbt = fbt_probetab[i];
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for (; fbt != NULL; fbt = fbt->fbtp_next)
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for (; fbt != NULL; fbt = fbt->fbtp_probenext)
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fbt_patch_tracepoint(fbt, fbt->fbtp_savedval);
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}
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}
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@ -204,40 +204,53 @@ fbt_provide_module(void *arg, modctl_t *lf)
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(void) linker_file_function_listall(lf, fbt_provide_module_function, modname);
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}
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static void
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fbt_destroy_one(fbt_probe_t *fbt)
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{
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fbt_probe_t *hash, *hashprev, *next;
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int ndx;
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ndx = FBT_ADDR2NDX(fbt->fbtp_patchpoint);
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for (hash = fbt_probetab[ndx], hashprev = NULL; hash != NULL;
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hash = hash->fbtp_hashnext, hashprev = hash) {
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if (hash == fbt) {
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if ((next = fbt->fbtp_tracenext) != NULL)
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next->fbtp_hashnext = hash->fbtp_hashnext;
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else
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next = hash->fbtp_hashnext;
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if (hashprev != NULL)
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hashprev->fbtp_hashnext = next;
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else
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fbt_probetab[ndx] = next;
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goto free;
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} else if (hash->fbtp_patchpoint == fbt->fbtp_patchpoint) {
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for (next = hash; next->fbtp_tracenext != NULL;
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next = next->fbtp_tracenext) {
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if (fbt == next->fbtp_tracenext) {
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next->fbtp_tracenext =
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fbt->fbtp_tracenext;
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goto free;
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}
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}
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}
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}
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panic("probe %p not found in hash table", fbt);
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free:
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free(fbt, M_FBT);
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}
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static void
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fbt_destroy(void *arg, dtrace_id_t id, void *parg)
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{
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fbt_probe_t *fbt = parg, *next, *hash, *last;
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fbt_probe_t *fbt = parg, *next;
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modctl_t *ctl;
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int ndx;
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do {
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ctl = fbt->fbtp_ctl;
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ctl->fbt_nentries--;
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/*
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* Now we need to remove this probe from the fbt_probetab.
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*/
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ndx = FBT_ADDR2NDX(fbt->fbtp_patchpoint);
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last = NULL;
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hash = fbt_probetab[ndx];
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while (hash != fbt) {
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ASSERT(hash != NULL);
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last = hash;
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hash = hash->fbtp_hashnext;
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}
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if (last != NULL) {
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last->fbtp_hashnext = fbt->fbtp_hashnext;
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} else {
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fbt_probetab[ndx] = fbt->fbtp_hashnext;
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}
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next = fbt->fbtp_next;
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free(fbt, M_FBT);
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next = fbt->fbtp_probenext;
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fbt_destroy_one(fbt);
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fbt = next;
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} while (fbt != NULL);
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}
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@ -265,14 +278,16 @@ fbt_enable(void *arg, dtrace_id_t id, void *parg)
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return;
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}
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for (; fbt != NULL; fbt = fbt->fbtp_next)
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for (; fbt != NULL; fbt = fbt->fbtp_probenext) {
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fbt_patch_tracepoint(fbt, fbt->fbtp_patchval);
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fbt->fbtp_enabled++;
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}
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}
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static void
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fbt_disable(void *arg, dtrace_id_t id, void *parg)
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{
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fbt_probe_t *fbt = parg;
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fbt_probe_t *fbt = parg, *hash;
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modctl_t *ctl = fbt->fbtp_ctl;
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ASSERT(ctl->nenabled > 0);
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@ -281,8 +296,21 @@ fbt_disable(void *arg, dtrace_id_t id, void *parg)
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if ((ctl->loadcnt != fbt->fbtp_loadcnt))
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return;
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for (; fbt != NULL; fbt = fbt->fbtp_next)
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fbt_patch_tracepoint(fbt, fbt->fbtp_savedval);
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for (; fbt != NULL; fbt = fbt->fbtp_probenext) {
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fbt->fbtp_enabled--;
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for (hash = fbt_probetab[FBT_ADDR2NDX(fbt->fbtp_patchpoint)];
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hash != NULL; hash = hash->fbtp_hashnext) {
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if (hash->fbtp_patchpoint == fbt->fbtp_patchpoint) {
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for (; hash != NULL; hash = hash->fbtp_tracenext)
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if (hash->fbtp_enabled > 0)
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break;
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break;
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}
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}
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if (hash == NULL)
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fbt_patch_tracepoint(fbt, fbt->fbtp_savedval);
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}
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}
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static void
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@ -296,7 +324,7 @@ fbt_suspend(void *arg, dtrace_id_t id, void *parg)
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if ((ctl->loadcnt != fbt->fbtp_loadcnt))
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return;
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for (; fbt != NULL; fbt = fbt->fbtp_next)
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for (; fbt != NULL; fbt = fbt->fbtp_probenext)
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fbt_patch_tracepoint(fbt, fbt->fbtp_savedval);
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}
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@ -311,7 +339,7 @@ fbt_resume(void *arg, dtrace_id_t id, void *parg)
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if ((ctl->loadcnt != fbt->fbtp_loadcnt))
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return;
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for (; fbt != NULL; fbt = fbt->fbtp_next)
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for (; fbt != NULL; fbt = fbt->fbtp_probenext)
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fbt_patch_tracepoint(fbt, fbt->fbtp_patchval);
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}
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@ -34,9 +34,18 @@
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#include "fbt_isa.h"
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/*
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* fbt_probe is a bit of a misnomer. One of these structures is created for
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* each trace point of an FBT probe. A probe might have multiple trace points
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* (e.g., a function with multiple return instructions), and different probes
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* might have a trace point at the same address (e.g., GNU ifuncs).
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*/
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typedef struct fbt_probe {
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struct fbt_probe *fbtp_hashnext;
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fbt_patchval_t *fbtp_patchpoint;
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struct fbt_probe *fbtp_hashnext; /* global hash table linkage */
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struct fbt_probe *fbtp_tracenext; /* next probe for tracepoint */
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struct fbt_probe *fbtp_probenext; /* next tracepoint for probe */
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int fbtp_enabled;
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fbt_patchval_t *fbtp_patchpoint;
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int8_t fbtp_rval;
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fbt_patchval_t fbtp_patchval;
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fbt_patchval_t fbtp_savedval;
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@ -46,7 +55,6 @@ typedef struct fbt_probe {
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modctl_t *fbtp_ctl;
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int fbtp_loadcnt;
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int fbtp_symindx;
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struct fbt_probe *fbtp_next;
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} fbt_probe_t;
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struct linker_file;
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fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
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name, FBT_RETURN, 3, fbt);
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} else {
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retfbt->fbtp_next = fbt;
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retfbt->fbtp_probenext = fbt;
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fbt->fbtp_id = retfbt->fbtp_id;
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}
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retfbt = fbt;
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@ -208,7 +208,7 @@ fbt_provide_module_function(linker_file_t lf, int symindx,
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fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
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name, FBT_RETURN, FBT_AFRAMES, fbt);
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} else {
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retfbt->fbtp_next = fbt;
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retfbt->fbtp_probenext = fbt;
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fbt->fbtp_id = retfbt->fbtp_id;
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}
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fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
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name, FBT_RETURN, 3, fbt);
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} else {
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retfbt->fbtp_next = fbt;
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retfbt->fbtp_probenext = fbt;
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fbt->fbtp_id = retfbt->fbtp_id;
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}
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retfbt = fbt;
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@ -67,6 +67,7 @@ fbt_invop(uintptr_t addr, struct trapframe *frame, uintptr_t rval)
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uintptr_t *stack;
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uintptr_t arg0, arg1, arg2, arg3, arg4;
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fbt_probe_t *fbt;
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int8_t fbtrval;
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#ifdef __amd64__
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stack = (uintptr_t *)frame->tf_rsp;
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@ -78,7 +79,11 @@ fbt_invop(uintptr_t addr, struct trapframe *frame, uintptr_t rval)
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cpu = &solaris_cpu[curcpu];
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fbt = fbt_probetab[FBT_ADDR2NDX(addr)];
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for (; fbt != NULL; fbt = fbt->fbtp_hashnext) {
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if ((uintptr_t)fbt->fbtp_patchpoint == addr) {
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if ((uintptr_t)fbt->fbtp_patchpoint != addr)
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continue;
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fbtrval = fbt->fbtp_rval;
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for (; fbt != NULL; fbt = fbt->fbtp_tracenext) {
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ASSERT(fbt->fbtp_rval == fbtrval);
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if (fbt->fbtp_roffset == 0) {
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#ifdef __amd64__
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/* fbt->fbtp_rval == DTRACE_INVOP_PUSHQ_RBP */
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@ -135,9 +140,8 @@ fbt_invop(uintptr_t addr, struct trapframe *frame, uintptr_t rval)
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rval, 0, 0, 0);
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cpu->cpu_dtrace_caller = 0;
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}
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return (fbt->fbtp_rval);
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}
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return (fbtrval);
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}
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return (0);
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@ -162,7 +166,7 @@ fbt_provide_module_function(linker_file_t lf, int symindx,
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{
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char *modname = opaque;
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const char *name = symval->name;
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fbt_probe_t *fbt, *retfbt;
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fbt_probe_t *fbt, *hash, *retfbt;
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int j;
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int size;
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uint8_t *instr, *limit;
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@ -224,8 +228,18 @@ fbt_provide_module_function(linker_file_t lf, int symindx,
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fbt->fbtp_patchval = FBT_PATCHVAL;
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fbt->fbtp_symindx = symindx;
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fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];
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fbt_probetab[FBT_ADDR2NDX(instr)] = fbt;
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for (hash = fbt_probetab[FBT_ADDR2NDX(instr)]; hash != NULL;
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hash = hash->fbtp_hashnext) {
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if (hash->fbtp_patchpoint == fbt->fbtp_patchpoint) {
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fbt->fbtp_tracenext = hash->fbtp_tracenext;
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hash->fbtp_tracenext = fbt;
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break;
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}
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}
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if (hash == NULL) {
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fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];
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fbt_probetab[FBT_ADDR2NDX(instr)] = fbt;
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}
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lf->fbt_nentries++;
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@ -301,7 +315,7 @@ fbt_provide_module_function(linker_file_t lf, int symindx,
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fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
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name, FBT_RETURN, 3, fbt);
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} else {
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retfbt->fbtp_next = fbt;
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retfbt->fbtp_probenext = fbt;
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fbt->fbtp_id = retfbt->fbtp_id;
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}
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