PR10491 Don't assign to REG_IP if it isn't an lvalue (s390 and ia64).

To fixup REG_IP to show the correct value after a [ku]probe trap we
assigned the address of the actual instruction pointer of the probed
instruction. That doesn't work on architectures, s390 and ia64, where
REG_IP is not a simple lvalue. Just don't try to fixup the address in
those cases. If this isn't enough, the uprobe_stmt_num.exp testcase
will point this out.

* runtime/regs.h: Define REG_IP_LVALUE for x86_64, i386, powerpc64 and arm.
* tapsets.cxx (dwarf_derived_probe_group::emit_module_decls): Only fixup
  REG_IP when REG_IP_LVALUE is defined.
  (uprobe_derived_probe_group::emit_module_decls): Likewise.
  (kprobe_derived_probe_group::emit_module_decls): Likewise.

2 files changed, 35 insertions, 0 deletions

diff --git a/runtime/regs.h b/runtime/regs.h
index 123d7601..d80cdf0a 100644
--- a/runtime/regs.h
+++ b/runtime/regs.h
@@ -13,17 +13,20 @@
 
 #if defined  (STAPCONF_X86_UNIREGS) && (defined (__x86_64__) || defined (__i386__))
 #define REG_IP(regs) regs->ip
+#define REG_IP_LVALUE 1
 #define REG_SP(regs) regs->sp
 #define REG_FP(regs) regs->bp
 
 #elif defined  (__x86_64__)
 
 #define REG_IP(regs) regs->rip
+#define REG_IP_LVALUE 1
 #define REG_SP(regs) regs->rsp
 
 #elif defined (__i386__)
 
 #define REG_IP(regs) regs->eip
+#define REG_IP_LVALUE 1
 #define REG_SP(regs) regs->esp
 #define REG_FP(regs) regs->ebp
 
@@ -34,12 +37,14 @@
 #elif defined (__powerpc64__)
 
 #define REG_IP(regs) regs->nip
+#define REG_IP_LVALUE 1
 #define REG_SP(regs) regs->gpr[1]
 #define REG_LINK(regs) regs->link
 
 #elif defined (__arm__)
 
 #define REG_IP(regs) regs->ARM_pc
+#define REG_IP_LVALUE 1
 #define REG_SP(regs) regs->ARM_sp
 #define REG_LINK(regs) regs->ARM_lr
 
diff --git a/tapsets.cxx b/tapsets.cxx
index b1ca2998..66cb2383 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -3030,6 +3030,8 @@ dwarf_derived_probe_group::emit_module_decls (systemtap_session& s)
   // 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
+  // But only for architectures where REG_IP is a proper lvalue. PR10491
+  s.op->newline() << "#ifdef REG_IP_LVALUE";
   s.op->newline() << "{";
   s.op->indent(1);
   s.op->newline() << "unsigned long kprobes_ip = REG_IP(c->regs);";
@@ -3037,6 +3039,9 @@ dwarf_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "(*sdp->ph) (c);";
   s.op->newline() << "REG_IP(regs) = kprobes_ip;";
   s.op->newline(-1) << "}";
+  s.op->newline() << "#else";
+  s.op->newline() << "(*sdp->ph) (c);";
+  s.op->newline() << "#endif";
 
   common_probe_entryfn_epilogue (s.op);
   s.op->newline() << "return 0;";
@@ -3064,6 +3069,8 @@ dwarf_derived_probe_group::emit_module_decls (systemtap_session& s)
   // 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
+  // But only for architectures where REG_IP is a proper lvalue. PR10491
+  s.op->newline() << "#ifdef REG_IP_LVALUE";
   s.op->newline() << "{";
   s.op->indent(1);
   s.op->newline() << "unsigned long kprobes_ip = REG_IP(c->regs);";
@@ -3071,6 +3078,9 @@ dwarf_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "(*sdp->ph) (c);";
   s.op->newline() << "REG_IP(regs) = kprobes_ip;";
   s.op->newline(-1) << "}";
+  s.op->newline() << "#else";
+  s.op->newline() << "(*sdp->ph) (c);";
+  s.op->newline() << "#endif";
 
   common_probe_entryfn_epilogue (s.op);
   s.op->newline() << "return 0;";
@@ -4447,6 +4457,8 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   // 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
+  // But only for architectures where REG_IP is a proper lvalue. PR10491
+  s.op->newline() << "#ifdef REG_IP_LVALUE";
   s.op->newline() << "{";
   s.op->indent(1);
   s.op->newline() << "unsigned long uprobes_ip = REG_IP(c->regs);";
@@ -4454,6 +4466,9 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "(*sups->ph) (c);";
   s.op->newline() << "REG_IP(regs) = uprobes_ip;";
   s.op->newline(-1) << "}";
+  s.op->newline() << "#else";
+  s.op->newline() << "(*sdp->ph) (c);";
+  s.op->newline() << "#endif";
 
   common_probe_entryfn_epilogue (s.op);
   s.op->newline(-1) << "}";
@@ -4470,6 +4485,8 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   // 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
+  // But only for architectures where REG_IP is a proper lvalue. PR10491
+  s.op->newline() << "#ifdef REG_IP_LVALUE";
   s.op->newline() << "{";
   s.op->indent(1);
   s.op->newline() << "unsigned long uprobes_ip = REG_IP(c->regs);";
@@ -4477,6 +4494,9 @@ uprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "(*sups->ph) (c);";
   s.op->newline() << "REG_IP(regs) = uprobes_ip;";
   s.op->newline(-1) << "}";
+  s.op->newline() << "#else";
+  s.op->newline() << "(*sdp->ph) (c);";
+  s.op->newline() << "#endif";
 
   common_probe_entryfn_epilogue (s.op);
   s.op->newline(-1) << "}";
@@ -4970,6 +4990,8 @@ kprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   // 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
+  // But only for architectures where REG_IP is a proper lvalue. PR10491
+  s.op->newline() << "#ifdef REG_IP_LVALUE";
   s.op->newline() << "{";
   s.op->indent(1);
   s.op->newline() << "unsigned long kprobes_ip = REG_IP(c->regs);";
@@ -4977,6 +4999,9 @@ kprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "(*sdp->ph) (c);";
   s.op->newline() << "REG_IP(regs) = kprobes_ip;";
   s.op->newline(-1) << "}";
+  s.op->newline() << "#else";
+  s.op->newline() << "(*sdp->ph) (c);";
+  s.op->newline() << "#endif";
 
   common_probe_entryfn_epilogue (s.op);
   s.op->newline() << "return 0;";
@@ -5004,6 +5029,8 @@ kprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   // 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
+  // But only for architectures where REG_IP is a proper lvalue. PR10491
+  s.op->newline() << "#ifdef REG_IP_LVALUE";
   s.op->newline() << "{";
   s.op->indent(1);
   s.op->newline() << "unsigned long kprobes_ip = REG_IP(c->regs);";
@@ -5011,6 +5038,9 @@ kprobe_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "(*sdp->ph) (c);";
   s.op->newline() << "REG_IP(regs) = kprobes_ip;";
   s.op->newline(-1) << "}";
+  s.op->newline() << "#else";
+  s.op->newline() << "(*sdp->ph) (c);";
+  s.op->newline() << "#endif";
 
   common_probe_entryfn_epilogue (s.op);
   s.op->newline() << "return 0;";