* sparc-linux-tdep.c (PSR_SYSCALL): Define.

	(sparc_linux_write_pc): New function.
	(sparc32_linux_init_abi): Register it.
	* sparc64-linux-tdep.c (TSTATE_SYSCALL): Define.
	(sparc64_linux_write_pc): New function.
	(sparc64_linux_init_abi): Register it.

3 files changed, 63 insertions, 0 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ab2dc68..0a25359 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,12 @@
 2008-05-11  David S. Miller  <davem@davemloft.net>
 
+	* sparc-linux-tdep.c (PSR_SYSCALL): Define.
+	(sparc_linux_write_pc): New function.
+	(sparc32_linux_init_abi): Register it.
+	* sparc64-linux-tdep.c (TSTATE_SYSCALL): Define.
+	(sparc64_linux_write_pc): New function.
+	(sparc64_linux_init_abi): Register it.
+
  	* sparc-linux-tdep.c, sparc64-linux-tdep.c: Use
 	dwarf2_append_unwinders(), not dwarf2_frame_sniffer.
 
diff --git a/gdb/sparc-linux-tdep.c b/gdb/sparc-linux-tdep.c
index 83d7589..c619ab1 100644
--- a/gdb/sparc-linux-tdep.c
+++ b/gdb/sparc-linux-tdep.c
@@ -211,6 +211,32 @@ sparc32_linux_collect_core_fpregset (const struct regset *regset,
   sparc32_collect_fpregset (regcache, regnum, fpregs);
 }
 
+/* Set the program counter for process PTID to PC.  */
+
+#define PSR_SYSCALL	0x00004000
+
+static void
+sparc_linux_write_pc (struct regcache *regcache, CORE_ADDR pc)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
+  ULONGEST psr;
+
+  regcache_cooked_write_unsigned (regcache, tdep->pc_regnum, pc);
+  regcache_cooked_write_unsigned (regcache, tdep->npc_regnum, pc + 4);
+
+  /* Clear the "in syscall" bit to prevent the kernel from
+     messing with the PCs we just installed, if we happen to be
+     within an interrupted system call that the kernel wants to
+     restart.
+
+     Note that after we return from the dummy call, the PSR et al.
+     registers will be automatically restored, and the kernel
+     continues to restart the system call at this point.  */
+  regcache_cooked_read_unsigned (regcache, SPARC32_PSR_REGNUM, &psr);
+  psr &= ~PSR_SYSCALL;
+  regcache_cooked_write_unsigned (regcache, SPARC32_PSR_REGNUM, psr);
+}
+
 
 
 static void
@@ -251,6 +277,8 @@ sparc32_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 
   /* Hook in the DWARF CFI frame unwinder.  */
   dwarf2_append_unwinders (gdbarch);
+
+  set_gdbarch_write_pc (gdbarch, sparc_linux_write_pc);
 }
 
 /* Provide a prototype to silence -Wmissing-prototypes.  */
diff --git a/gdb/sparc64-linux-tdep.c b/gdb/sparc64-linux-tdep.c
index 9f752b3..05218e1 100644
--- a/gdb/sparc64-linux-tdep.c
+++ b/gdb/sparc64-linux-tdep.c
@@ -174,6 +174,32 @@ sparc64_linux_collect_core_fpregset (const struct regset *regset,
   sparc64_collect_fpregset (regcache, regnum, fpregs);
 }
 
+/* Set the program counter for process PTID to PC.  */
+
+#define TSTATE_SYSCALL	0x0000000000000020ULL
+
+static void
+sparc64_linux_write_pc (struct regcache *regcache, CORE_ADDR pc)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
+  ULONGEST state;
+
+  regcache_cooked_write_unsigned (regcache, tdep->pc_regnum, pc);
+  regcache_cooked_write_unsigned (regcache, tdep->npc_regnum, pc + 4);
+
+  /* Clear the "in syscall" bit to prevent the kernel from
+     messing with the PCs we just installed, if we happen to be
+     within an interrupted system call that the kernel wants to
+     restart.
+
+     Note that after we return from the dummy call, the TSTATE et al.
+     registers will be automatically restored, and the kernel
+     continues to restart the system call at this point.  */
+  regcache_cooked_read_unsigned (regcache, SPARC64_STATE_REGNUM, &state);
+  state &= ~TSTATE_SYSCALL;
+  regcache_cooked_write_unsigned (regcache, SPARC64_STATE_REGNUM, state);
+}
+
 
 
 static void
@@ -211,6 +237,8 @@ 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;
+
+  set_gdbarch_write_pc (gdbarch, sparc64_linux_write_pc);
 }