PR10458. User actual breakpoint address for [ku]probe[ret].

Setup the pt_regs REG_IP to the actual breakpoint address before
entering a probe handler for [ku]probe[ret] (and restore it after
returning). This helps getting symbol resolution and backtraces
more correct and makes it more conform with other probe handlers
like the iutrace and profile timers that also provide pt_regs
(which untill now exhibited off-by-one errors while unwinding).

* tapsets.cxx (dwarf_derived_probe_group::emit_module_decls):
  Setup REG_IP correctly before calling enter_kprobe_probe
  and enter_kretprobe_probe, and restore afterwards.
  (uprobe_derived_probe_group::emit_module_decls): Likewise for
  enter_uprobe_probe and enter_uretprobe_probe.
  (kprobe_derived_probe_group::emit_module_decls): Likewise for
  enter_kprobe2_probe and enter_kretprobe2_probe.
* runtime/unwind/i386.h (arch_unw_init_frame_info): Initialize
  info->call_frame to zero.
* runtime/unwind/x86_64.h (arch_unw_init_frame_info): Likewise.

1 files changed, 66 insertions, 0 deletions

diff --git a/tapsets.cxx b/tapsets.cxx
index 2d68ddd4..bd33fb0b 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -2986,7 +2986,18 @@ dwarf_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->line() << "];";
   common_probe_entryfn_prologue (s.op, "STAP_SESSION_RUNNING", "sdp->pp");
   s.op->newline() << "c->regs = regs;";
+
+  // Make it look like the IP is set as it wouldn't have been replaced
+  // by a breakpoint instruction when calling real probe handler. Reset
+  // IP regs on return, so we don't confuse kprobes. PR10458
+  s.op->newline() << "{";
+  s.op->indent(1);
+  s.op->newline() << "unsigned long kprobes_ip = REG_IP(c->regs);";
+  s.op->newline() << "REG_IP(regs) = (unsigned long) inst->addr;";
   s.op->newline() << "(*sdp->ph) (c);";
+  s.op->newline() << "REG_IP(regs) = kprobes_ip;";
+  s.op->newline(-1) << "}";
+
   common_probe_entryfn_epilogue (s.op);
   s.op->newline() << "return 0;";
   s.op->newline(-1) << "}";
@@ -3009,7 +3020,18 @@ dwarf_derived_probe_group::emit_module_decls (systemtap_session& s)
   common_probe_entryfn_prologue (s.op, "STAP_SESSION_RUNNING", "sdp->pp");
   s.op->newline() << "c->regs = regs;";
   s.op->newline() << "c->pi = inst;"; // for assisting runtime's backtrace logic
+
+  // Make it look like the IP is set as it wouldn't have been replaced
+  // by a breakpoint instruction when calling real probe handler. Reset
+  // IP regs on return, so we don't confuse kprobes. PR10458
+  s.op->newline() << "{";
+  s.op->indent(1);
+  s.op->newline() << "unsigned long kprobes_ip = REG_IP(c->regs);";
+  s.op->newline() << "REG_IP(regs) = (unsigned long) inst->rp->kp.addr;";
   s.op->newline() << "(*sdp->ph) (c);";
+  s.op->newline() << "REG_IP(regs) = kprobes_ip;";
+  s.op->newline(-1) << "}";
+
   common_probe_entryfn_epilogue (s.op);
   s.op->newline() << "return 0;";
   s.op->newline(-1) << "}";
@@ -4381,7 +4403,18 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "if (sup->spec_index < 0 ||"
                   << "sup->spec_index >= " << probes.size() << ") return;"; // XXX: should not happen
   s.op->newline() << "c->regs = regs;";
+
+  // Make it look like the IP is set as it would in the actual user
+  // task when calling real probe handler. Reset IP regs on return, so
+  // we don't confuse uprobes. PR10458
+  s.op->newline() << "{";
+  s.op->indent(1);
+  s.op->newline() << "unsigned long uprobes_ip = REG_IP(c->regs);";
+  s.op->newline() << "REG_IP(regs) = inst->vaddr;";
   s.op->newline() << "(*sups->ph) (c);";
+  s.op->newline() << "REG_IP(regs) = uprobes_ip;";
+  s.op->newline(-1) << "}";
+
   common_probe_entryfn_epilogue (s.op);
   s.op->newline(-1) << "}";
 
@@ -4393,7 +4426,18 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
                   << "sup->spec_index >= " << probes.size() << ") return;"; // XXX: should not happen
   // XXX: kretprobes saves "c->pi = inst;" too
   s.op->newline() << "c->regs = regs;";
+
+  // Make it look like the IP is set as it would in the actual user
+  // task when calling real probe handler. Reset IP regs on return, so
+  // we don't confuse uprobes. PR10458
+  s.op->newline() << "{";
+  s.op->indent(1);
+  s.op->newline() << "unsigned long uprobes_ip = REG_IP(c->regs);";
+  s.op->newline() << "REG_IP(regs) = inst->rp->u.vaddr;";
   s.op->newline() << "(*sups->ph) (c);";
+  s.op->newline() << "REG_IP(regs) = uprobes_ip;";
+  s.op->newline(-1) << "}";
+
   common_probe_entryfn_epilogue (s.op);
   s.op->newline(-1) << "}";
 
@@ -4882,7 +4926,18 @@ kprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->line() << "];";
   common_probe_entryfn_prologue (s.op, "STAP_SESSION_RUNNING", "sdp->pp");
   s.op->newline() << "c->regs = regs;";
+
+  // Make it look like the IP is set as it wouldn't have been replaced
+  // by a breakpoint instruction when calling real probe handler. Reset
+  // IP regs on return, so we don't confuse kprobes. PR10458
+  s.op->newline() << "{";
+  s.op->indent(1);
+  s.op->newline() << "unsigned long kprobes_ip = REG_IP(c->regs);";
+  s.op->newline() << "REG_IP(regs) = (unsigned long) inst->addr;";
   s.op->newline() << "(*sdp->ph) (c);";
+  s.op->newline() << "REG_IP(regs) = kprobes_ip;";
+  s.op->newline(-1) << "}";
+
   common_probe_entryfn_epilogue (s.op);
   s.op->newline() << "return 0;";
   s.op->newline(-1) << "}";
@@ -4905,7 +4960,18 @@ kprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   common_probe_entryfn_prologue (s.op, "STAP_SESSION_RUNNING", "sdp->pp");
   s.op->newline() << "c->regs = regs;";
   s.op->newline() << "c->pi = inst;"; // for assisting runtime's backtrace logic
+
+  // Make it look like the IP is set as it wouldn't have been replaced
+  // by a breakpoint instruction when calling real probe handler. Reset
+  // IP regs on return, so we don't confuse kprobes. PR10458
+  s.op->newline() << "{";
+  s.op->indent(1);
+  s.op->newline() << "unsigned long kprobes_ip = REG_IP(c->regs);";
+  s.op->newline() << "REG_IP(regs) = (unsigned long) inst->rp->kp.addr;";
   s.op->newline() << "(*sdp->ph) (c);";
+  s.op->newline() << "REG_IP(regs) = kprobes_ip;";
+  s.op->newline(-1) << "}";
+
   common_probe_entryfn_epilogue (s.op);
   s.op->newline() << "return 0;";
   s.op->newline(-1) << "}";