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-rw-r--r--tapsets.cxx138
1 files changed, 85 insertions, 53 deletions
diff --git a/tapsets.cxx b/tapsets.cxx
index a5717d16..4b6305b2 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -4593,6 +4593,7 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
s.op->newline() << "static struct stap_uprobe {";
s.op->newline(1) << "union { struct uprobe up; struct uretprobe urp; };";
s.op->newline() << "int spec_index;"; // index into stap_uprobe_specs; <0 == free && unregistered
+ s.op->newline() << "unsigned long sdt_sem_address;";
s.op->newline(-1) << "} stap_uprobes [MAXUPROBES];"; // XXX: consider a slab cache or somesuch
s.op->newline() << "DEFINE_MUTEX(stap_uprobes_lock);"; // protects against concurrent registration/unregistration
@@ -4651,14 +4652,6 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
s.op->assert_0_indent();
- s.op->newline() << "unsigned long sdt_sem_address [] = {";
- for (unsigned i =0; i<probes.size(); i++)
- s.op->line() << "0,";
- s.op->line() << "0};";
- s.op->newline() << "unsigned long sdt_sem_tid [] = {";
- for (unsigned i =0; i<probes.size(); i++)
- s.op->line() << "0,";
- s.op->line() << "0};";
s.op->newline() << "static const struct stap_uprobe_spec {"; // NB: read-only structure
s.op->newline(1) << "unsigned tfi;"; // index into stap_uprobe_finders[]
s.op->newline() << "unsigned return_p:1;";
@@ -4761,13 +4754,15 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
s.op->newline(1) << "int handled_p = 0;";
s.op->newline() << "int slotted_p = 0;";
s.op->newline() << "const struct stap_uprobe_spec *sups = &stap_uprobe_specs [spec_index];";
+ s.op->newline() << "struct stap_uprobe *sup;";
+ s.op->newline() << "pid_t sdt_sem_pid;";
s.op->newline() << "int rc = 0;";
s.op->newline() << "int i;";
s.op->newline() << "if (likely(sups->tfi != tfi)) continue;";
// skip probes with an address beyond this map event; should not
// happen unless a shlib/exec got mmapped in weirdly piecemeal
- s.op->newline() << "if (likely(sups->address >= length)) continue;";
+ s.op->newline() << "if (likely((vm_flags & VM_EXEC) && ((sups->address >= length) || (sups->sdt_sem_offset >= length)))) continue;";
// Found a uprobe_spec for this stap_uprobe_tf. Need to lock the
// stap_uprobes[] array to allocate a free spot, but then we can
@@ -4775,10 +4770,11 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
s.op->newline() << "mutex_lock (& stap_uprobes_lock);";
s.op->newline() << "for (i=0; i<MAXUPROBES; i++) {"; // XXX: slow linear search
- s.op->newline(1) << "struct stap_uprobe *sup = & stap_uprobes[i];";
+ s.op->newline(1) << "sup = & stap_uprobes[i];";
// register new uprobe
- s.op->newline() << "if (sup->spec_index < 0) {";
+ // We make two passes for semaphores; see _stap_uprobe_change_semaphore_plus
+ s.op->newline() << "if (sup->spec_index < 0 || (sups->sdt_sem_offset && vm_flags & VM_WRITE && sup->spec_index == spec_index)) {";
s.op->newline(1) << "#if (UPROBES_API_VERSION < 2)";
// See PR6829 comment.
s.op->newline() << "if (sup->spec_index == -1 && sup->up.kdata != NULL) continue;";
@@ -4803,28 +4799,18 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
// was full (registration; MAXUPROBES) or that no matching entry was
// found (unregistration; should not happen).
- s.op->newline() << "if (sups->sdt_sem_offset && (sdt_sem_tid[spec_index] != tsk->tgid || sdt_sem_address[spec_index] == 0)) {";
+ s.op->newline() << "sdt_sem_pid = (sups->return_p ? sup->urp.u.pid : sup->up.pid);";
+ s.op->newline() << "if (sups->sdt_sem_offset && (sdt_sem_pid != tsk->tgid || sup->sdt_sem_address == 0)) {";
s.op->indent(1);
// If the probe is in the executable itself, the offset *is* the address.
s.op->newline() << "if (vm_flags & VM_EXECUTABLE) {";
s.op->indent(1);
- s.op->newline() << "sdt_sem_address[spec_index] = relocation + sups->sdt_sem_offset;";
- s.op->newline() << "sdt_sem_tid[spec_index] = tsk->tgid;";
+ s.op->newline() << "sup->sdt_sem_address = relocation + sups->sdt_sem_offset;";
s.op->newline(-1) << "}";
- // If the probe is in a .so, we have to calculate the address
- // when the initial mmap maps the entire solib, e.g.
- // 7f089885a000-7f089885b000 rw-p- libtcl.so
- // A subsequent mmap maps in the writeable segment where the
- // semaphore control variable lives, which is when the variable is set.
- // 7f089850d000-7f0898647000 r-xp- libtcl.so
- // 7f0898647000-7f0898846000 ---p libtcl.so
- // 7f0898846000-7f089885b000 rw-p- libtcl.so
- // If the task changes, then recalculate the address.
s.op->newline() << "else {";
s.op->indent(1);
- s.op->newline() << "sdt_sem_address[spec_index] = (relocation - offset) + sups->sdt_sem_offset;";
- s.op->newline() << "sdt_sem_tid[spec_index] = tsk->tgid;";
+ s.op->newline() << "sup->sdt_sem_address = (relocation - offset) + sups->sdt_sem_offset;";
s.op->newline(-1) << "}";
s.op->newline(-1) << "}"; // sdt_sem_offset
@@ -4841,23 +4827,9 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
s.op->newline() << "sup->up.handler = &enter_uprobe_probe;";
s.op->newline() << "rc = register_uprobe (& sup->up);";
- s.op->newline() << "if (sdt_sem_address[spec_index]) {";
- s.op->newline(1) << "unsigned short sdt_semaphore = 0;"; // NB: fixed size
- s.op->newline() << "if (get_user (sdt_semaphore, (unsigned short __user*) sdt_sem_address[spec_index]) == 0) {";
- // We have an executable or a writeable segment of a .so
- s.op->newline(1) << "if (vm_flags == 0 || vm_flags & VM_WRITE) {";
- s.op->newline(1) << "sdt_semaphore ++;";
- s.op->newline() << "put_user (sdt_semaphore, (unsigned short __user*) sdt_sem_address[spec_index]);";
- s.op->newline(-1) << "}";
- s.op->newline(-1) << "}"; // sdt_sem_address
- // XXX: error handling in __access_process_vm!
- // XXX: need to analyze possibility of race condition
-
s.op->newline(-1) << "}";
- s.op->newline(-1) << "}";
-
- s.op->newline() << "if (rc && !(vm_flags & VM_WRITE)) {"; // failed to register
+ s.op->newline() << "if (rc) {"; // failed to register
s.op->newline(1) << "_stp_warn (\"u*probe failed %s[%d] '%s' addr %p rc %d\\n\", tsk->comm, tsk->tgid, sups->pp, (void*)(relocation + sups->address), rc);";
// NB: we need to release this slot, so we need to borrow the mutex temporarily.
s.op->newline() << "mutex_lock (& stap_uprobes_lock);";
@@ -4890,6 +4862,59 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
s.op->assert_0_indent();
+ s.op->newline();
+ s.op->newline() << "static int stap_uprobe_change_semaphore_plus (struct task_struct *tsk, unsigned long relocation, unsigned long length, const struct stap_uprobe_tf *stf) {";
+ s.op->newline(1) << "int tfi = (stf - stap_uprobe_finders);";
+ s.op->newline() << "int spec_index;";
+ s.op->newline() << "int rc = 0;";
+ s.op->newline() << "struct stap_uprobe *sup;";
+ s.op->newline() << "int i;";
+
+ // We make two passes for semaphores.
+ // The first pass, stap_uprobe_change_plus, calculates the address of the
+ // semaphore. If the probe is in a .so, we calculate the
+ // address when the initial mmap maps the entire solib, e.g.
+ // 7f089885a000-7f089885b000 rw-p- libtcl.so
+ // A subsequent mmap maps in the writeable segment where the
+ // semaphore control variable lives, e.g.
+ // 7f089850d000-7f0898647000 r-xp- libtcl.so
+ // 7f0898647000-7f0898846000 ---p libtcl.so
+ // 7f0898846000-7f089885b000 rw-p- libtcl.so
+ // The second pass, stap_uprobe_change_semaphore_plus, sets the semaphore.
+ // If the probe is in a .so this will be when the writeable segment of the .so
+ // is mapped in. If the task changes, then recalculate the address.
+
+ s.op->newline() << "for (i=0; i<MAXUPROBES; i++) {"; // XXX: slow linear search
+ s.op->newline(1) << "sup = & stap_uprobes[i];";
+ s.op->newline() << "if (sup->spec_index == -1) continue;";
+ s.op->newline() << "if (sup->sdt_sem_address != 0 && !(sup->up.pid == tsk->tgid "
+ << "&& sup->sdt_sem_address >= relocation && sup->sdt_sem_address < relocation+length)) continue;";
+
+ s.op->newline() << "if (sup->sdt_sem_address) {";
+ s.op->newline(1) << "unsigned short sdt_semaphore = 0;"; // NB: fixed size
+ s.op->newline() << "if ((rc = get_user (sdt_semaphore, (unsigned short __user*) sup->sdt_sem_address)) == 0) {";
+ s.op->newline(1) << "sdt_semaphore ++;";
+
+ s.op->newline() << "#ifdef DEBUG_UPROBES";
+ s.op->newline() << "{";
+ s.op->newline(1) << "const struct stap_uprobe_spec *sups = &stap_uprobe_specs [sup->spec_index];";
+ s.op->newline() << "_stp_dbug(__FUNCTION__,__LINE__, \"+semaphore %#x @ %#lx spec %d idx %d task %d\\n\", "
+ << "sdt_semaphore, sup->sdt_sem_address, sup->spec_index, i, tsk->tgid);";
+ s.op->newline(-1) << "}";
+ s.op->newline() << "#endif";
+
+ s.op->newline() << "rc = put_user (sdt_semaphore, (unsigned short __user*) sup->sdt_sem_address);";
+ s.op->newline(-1) << "}";
+ // XXX: need to analyze possibility of race condition
+
+ s.op->newline(-1) << "}";
+ s.op->newline(-1) << "}";
+ s.op->newline() << "return rc;";
+ s.op->newline(-1) << "}";
+
+ s.op->assert_0_indent();
+
+
// Removing/unmapping a uprobe is simpler than adding one (in the _plus function above).
// We need not care about stap_uprobe_finders or anything, we just scan through stap_uprobes[]
// for a live probe within the given address range, and kill it.
@@ -4989,9 +5014,12 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
s.op->newline() << "#endif";
// ET_EXEC events are modeled as if shlib events, but with 0 relocation bases
- s.op->newline() << "if (register_p)";
- s.op->newline(1) << "return stap_uprobe_change_plus (tsk, 0, TASK_SIZE, stf, 0, 0);";
- s.op->newline(-1) << "else";
+ s.op->newline() << "if (register_p) {";
+ // s.op->newline(1) << "return stap_uprobe_change_plus (tsk, 0, TASK_SIZE, stf, 0, 0);";
+ s.op->newline(1) << "int rc = stap_uprobe_change_plus (tsk, 0, TASK_SIZE, stf, 0, 0);";
+ s.op->newline() << "stap_uprobe_change_semaphore_plus (tsk, 0, TASK_SIZE, stf);";
+ s.op->newline() << "return rc;";
+ s.op->newline(-1) << "} else";
s.op->newline(1) << "return stap_uprobe_change_minus (tsk, 0, TASK_SIZE, stf);";
s.op->indent(-1);
s.op->newline(-1) << "}";
@@ -5008,14 +5036,19 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
// 2 - the shared library we're interested in
s.op->newline() << "if (path == NULL || strcmp (path, stf->pathname)) return 0;";
// 3 - mapping should be executable or writeable (for semaphore in .so)
- s.op->newline() << "if (!((vm_flags & VM_EXEC) || (vm_flags & VM_WRITE))) return 0;";
-
- s.op->newline() << "#ifdef DEBUG_TASK_FINDER_VMA";
- s.op->newline() << "_stp_dbug (__FUNCTION__,__LINE__, \"+mmap pid %d path %s addr %p length %u offset %p stf %p %p path %s\\n\", "
+ s.op->newline() << "if (vm_flags & VM_EXEC) {";
+ s.op->newline(1) << "#ifdef DEBUG_TASK_FINDER_VMA";
+ s.op->newline() << "_stp_dbug (__FUNCTION__,__LINE__, \"+mmap R-X pid %d path %s addr %p length %u offset %p stf %p %p path %s\\n\", "
<< "tsk->tgid, path, (void *) addr, (unsigned)length, (void*) offset, tgt, stf, stf->pathname);";
s.op->newline() << "#endif";
-
s.op->newline() << "return stap_uprobe_change_plus (tsk, addr, length, stf, offset, vm_flags);";
+ s.op->newline(-1) << "} else if (vm_flags & VM_WRITE) {";
+ s.op->newline(1) << "#ifdef DEBUG_TASK_FINDER_VMA";
+ s.op->newline() << "_stp_dbug (__FUNCTION__,__LINE__, \"+mmap RW- pid %d path %s addr %p length %u offset %p stf %p %p path %s\\n\", "
+ << "tsk->tgid, path, (void *) addr, (unsigned)length, (void*) offset, tgt, stf, stf->pathname);";
+ s.op->newline() << "#endif";
+ s.op->newline() << "return stap_uprobe_change_semaphore_plus (tsk, addr, length, stf);";
+ s.op->newline(-1) << "} else return 0;";
s.op->newline(-1) << "}";
s.op->assert_0_indent();
@@ -5093,7 +5126,7 @@ uprobe_derived_probe_group::emit_module_exit (systemtap_session& s)
s.op->newline() << "if (sup->spec_index < 0) continue;"; // free slot
// PR10655: decrement that ENABLED semaphore
- s.op->newline() << "if (sdt_sem_address[sup->spec_index]) {";
+ s.op->newline() << "if (sup->sdt_sem_address) {";
s.op->newline(1) << "unsigned short sdt_semaphore;"; // NB: fixed size
s.op->newline() << "pid_t pid = (sups->return_p ? sup->urp.u.pid : sup->up.pid);";
s.op->newline() << "struct task_struct *tsk;";
@@ -5113,14 +5146,13 @@ uprobe_derived_probe_group::emit_module_exit (systemtap_session& s)
s.op->newline() << "#endif /* 2.6.31 */";
s.op->newline() << "if (tsk) {"; // just in case the thing exited while we weren't watching
- s.op->newline(1) << "if (get_user (sdt_semaphore, (unsigned short __user*) sdt_sem_address[sup->spec_index]) == 0) {";
+ s.op->newline(1) << "if (get_user (sdt_semaphore, (unsigned short __user*) sup->sdt_sem_address) == 0) {";
s.op->newline(1) << "sdt_semaphore --;";
s.op->newline() << "#ifdef DEBUG_UPROBES";
- s.op->newline() << "_stp_dbug (__FUNCTION__,__LINE__, \"-semaphore %#x @ %#lx\\n\", sdt_semaphore, sdt_sem_address[sup->spec_index]);";
+ s.op->newline() << "_stp_dbug (__FUNCTION__,__LINE__, \"-semaphore %#x @ %#lx\\n\", sdt_semaphore, sup->sdt_sem_address);";
s.op->newline() << "#endif";
- s.op->newline() << "put_user (sdt_semaphore, (unsigned short __user*) sdt_sem_address[sup->spec_index]);";
+ s.op->newline() << "put_user (sdt_semaphore, (unsigned short __user*) sup->sdt_sem_address);";
s.op->newline(-1) << "}";
- // XXX: error handling in __access_process_vm!
// XXX: need to analyze possibility of race condition
s.op->newline(-1) << "}";
s.op->newline() << "rcu_read_unlock();";
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