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authorJose E. Marchesi <jose.marchesi@oracle.com>2013-11-18 04:37:05 -0800
committerJose E. Marchesi <jose.marchesi@oracle.com>2013-11-18 04:37:05 -0800
commitd0b5971ae7b8709c28a7a1638413426d8749d976 (patch)
treeed6837627bce0dc681f157afa2651fe563b02de4 /gdb
parent4b4589ada7e88f2f36d264a173d95ed5994b3acb (diff)
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sparc: support single-stepping over longjmp calls.
2013-11-18 Jose E. Marchesi <jose.marchesi@oracle.com> * sparc-tdep.c (sparc_is_annulled_branch_insn): New function. * sparc-tdep.h: And its prototype. * sparc64-linux-tdep.c (sparc64_linux_get_longjmp_target): New function. (sparc64_linux_init_abi): Register the get_longjmp_target hook.
Diffstat (limited to 'gdb')
-rw-r--r--gdb/ChangeLog9
-rw-r--r--gdb/sparc-tdep.c31
-rw-r--r--gdb/sparc-tdep.h2
-rw-r--r--gdb/sparc64-linux-tdep.c47
4 files changed, 89 insertions, 0 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 7fc09e0..2042e49 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,12 @@
+2013-11-18 Jose E. Marchesi <jose.marchesi@oracle.com>
+
+ * sparc-tdep.c (sparc_is_annulled_branch_insn): New function.
+ * sparc-tdep.h: And its prototype.
+
+ * sparc64-linux-tdep.c (sparc64_linux_get_longjmp_target): New
+ function.
+ (sparc64_linux_init_abi): Register the get_longjmp_target hook.
+
2013-11-18 Pedro Alves <palves@redhat.com>
* dwarf2-frame.c (read_addr_from_reg): Remove stale comment and
diff --git a/gdb/sparc-tdep.c b/gdb/sparc-tdep.c
index 53014a0..1a200e0 100644
--- a/gdb/sparc-tdep.c
+++ b/gdb/sparc-tdep.c
@@ -121,6 +121,37 @@ sparc_is_unimp_insn (CORE_ADDR pc)
return ((insn & 0xc1c00000) == 0);
}
+/* Return non-zero if the instruction corresponding to PC is an
+ "annulled" branch, i.e. the annul bit is set. */
+
+int
+sparc_is_annulled_branch_insn (CORE_ADDR pc)
+{
+ /* The branch instructions featuring an annul bit can be identified
+ by the following bit patterns:
+
+ OP=0
+ OP2=1: Branch on Integer Condition Codes with Prediction (BPcc).
+ OP2=2: Branch on Integer Condition Codes (Bcc).
+ OP2=5: Branch on FP Condition Codes with Prediction (FBfcc).
+ OP2=6: Branch on FP Condition Codes (FBcc).
+ OP2=3 && Bit28=0:
+ Branch on Integer Register with Prediction (BPr).
+
+ This leaves out ILLTRAP (OP2=0), SETHI/NOP (OP2=4) and the V8
+ coprocessor branch instructions (Op2=7). */
+
+ const unsigned long insn = sparc_fetch_instruction (pc);
+ const unsigned op2 = X_OP2 (insn);
+
+ if ((X_OP (insn) == 0)
+ && ((op2 == 1) || (op2 == 2) || (op2 == 5) || (op2 == 6)
+ || ((op2 == 3) && ((insn & 0x10000000) == 0))))
+ return X_A (insn);
+ else
+ return 0;
+}
+
/* OpenBSD/sparc includes StackGhost, which according to the author's
website http://stackghost.cerias.purdue.edu "... transparently and
automatically protects applications' stack frames; more
diff --git a/gdb/sparc-tdep.h b/gdb/sparc-tdep.h
index cafc627..6fd7641 100644
--- a/gdb/sparc-tdep.h
+++ b/gdb/sparc-tdep.h
@@ -220,6 +220,8 @@ extern void sparc32_collect_fpregset (const struct sparc_fpregset *fpregset,
const struct regcache *regcache,
int regnum, void *fpregs);
+extern int sparc_is_annulled_branch_insn (CORE_ADDR pc);
+
/* Functions and variables exported from sparc-sol2-tdep.c. */
/* Register offsets for Solaris 2. */
diff --git a/gdb/sparc64-linux-tdep.c b/gdb/sparc64-linux-tdep.c
index 3f53f6c..f6ddff0 100644
--- a/gdb/sparc64-linux-tdep.c
+++ b/gdb/sparc64-linux-tdep.c
@@ -233,6 +233,50 @@ sparc64_linux_get_syscall_number (struct gdbarch *gdbarch,
}
+/* Implement the "get_longjmp_target" gdbarch method. */
+
+static int
+sparc64_linux_get_longjmp_target (struct frame_info *frame, CORE_ADDR *pc)
+{
+ struct gdbarch *gdbarch = get_frame_arch (frame);
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+ CORE_ADDR jb_addr;
+ gdb_byte buf[8];
+
+ jb_addr = get_frame_register_unsigned (frame, SPARC_O0_REGNUM);
+
+ /* setjmp and longjmp in SPARC64 are implemented in glibc using the
+ setcontext and getcontext system calls respectively. These
+ system calls operate on ucontext_t structures, which happen to
+ partially have the same structure than jmp_buf. However the
+ ucontext returned by getcontext, and thus the jmp_buf structure
+ returned by setjmp, contains the context of the trap instruction
+ in the glibc __[sig]setjmp wrapper, not the context of the user
+ code calling setjmp.
+
+ %o7 in the jmp_buf structure is stored at offset 18*8 in the
+ mc_gregs array, which is itself located at offset 32 into
+ jmp_buf. See bits/setjmp.h. This register contains the address
+ of the 'call setjmp' instruction in user code.
+
+ In order to determine the longjmp target address in the
+ initiating frame we need to examine the call instruction itself,
+ in particular whether the annul bit is set. If it is not set
+ then we need to jump over the instruction at the delay slot. */
+
+ if (target_read_memory (jb_addr + 32 + (18 * 8), buf, 8))
+ return 0;
+
+ *pc = extract_unsigned_integer (buf, 8, gdbarch_byte_order (gdbarch));
+
+ if (!sparc_is_annulled_branch_insn (*pc))
+ *pc += 4; /* delay slot insn */
+ *pc += 4; /* call insn */
+
+ return 1;
+}
+
+
static void
sparc64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
@@ -272,6 +316,9 @@ sparc64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
/* Make sure we can single-step over signal return system calls. */
tdep->step_trap = sparc64_linux_step_trap;
+ /* Make sure we can single-step over longjmp calls. */
+ set_gdbarch_get_longjmp_target (gdbarch, sparc64_linux_get_longjmp_target);
+
set_gdbarch_write_pc (gdbarch, sparc64_linux_write_pc);
/* Functions for 'catch syscall'. */