[PATCH][SH] Signal handler unwinding for SH-Linux

Chung-Lin Tang
2012-04-29T08:05:26Z

[-- Attachment #1: Type: text/plain, Size: 1108 bytes --]

Hi,

This patch adds support for unwinding across signal handlers for
SH/Linux. The implementation is quite straightforward, following the
overall pattern for recognizing signal frames using the 'tramp_frame'
facilities. Currently, only 32-bit SH support is implemented.

The test results show improvement on many sighandler related tests, with
no regressions. Some gdb.base/sigbpt.exp tests change from FAIL->KFAIL,
though I'm not completely sure what that indicates.

Thanks,
Chung-Lin

2012-04-29 Chung-Lin Tang <cltang@codesourcery.com>

* sh-linux-tdep.c: Include trad-frame.h and tramp-frame.h.
(sh_linux_sigtramp_cache): New function.
(sh_linux_sigreturn_init): New function.
(sh_linux_rt_sigreturn_init): New function.
(SH_MOVW,SH_TRAP,SH_OR_R0_R0): New symbols for instruction
patterns.
(SH_NR_SIGRETURN,SH_NR_RT_SIGRETURN): New symbols for sigreturn
syscall codes.
(sh_linux_sigreturn_tramp_frame): New tramp_frame definition.
(sh_linux_rt_sigreturn_tramp_frame): Likewise.
(sh_linux_init_abi): Add init calls to register new tramp_frame
definitions under 32-bit SH, update comments.

[-- Attachment #2: sh-sighandler-unwind.patch --]
[-- Type: text/plain, Size: 4837 bytes --]

Index: gdb/sh-linux-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/sh-linux-tdep.c,v
retrieving revision 1.13
diff -u -p -r1.13 sh-linux-tdep.c
--- gdb/sh-linux-tdep.c 4 Jan 2012 08:17:10 -0000 1.13
+++ gdb/sh-linux-tdep.c 29 Apr 2012 07:45:43 -0000
@@ -23,6 +23,9 @@
#include "solib-svr4.h"
#include "symtab.h"

+#include "trad-frame.h"
+#include "tramp-frame.h"
+
#include "glibc-tdep.h"
#include "sh-tdep.h"
#include "linux-tdep.h"
@@ -70,6 +73,110 @@ static const struct sh_corefile_regmap f
{-1 /* Terminator. */, 0}
};

+/* SH signal handler frame support. */
+
+static void
+sh_linux_sigtramp_cache (struct frame_info *this_frame,
+ struct trad_frame_cache *this_cache,
+ CORE_ADDR func, int regs_offset)
+{
+ int i;
+ struct gdbarch *gdbarch = get_frame_arch (this_frame);
+ CORE_ADDR base = get_frame_register_unsigned (this_frame,
+ gdbarch_sp_regnum (gdbarch));
+ CORE_ADDR regs = base + regs_offset;
+
+ for (i = 0; i < 18; i++)
+ trad_frame_set_reg_addr (this_cache, i, regs + i * 4);
+
+ trad_frame_set_reg_addr (this_cache, SR_REGNUM, regs + 18 * 4);
+ trad_frame_set_reg_addr (this_cache, GBR_REGNUM, regs + 19 * 4);
+ trad_frame_set_reg_addr (this_cache, MACH_REGNUM, regs + 20 * 4);
+ trad_frame_set_reg_addr (this_cache, MACL_REGNUM, regs + 21 * 4);
+
+ /* Restore FP state if we have an FPU. */
+ if (gdbarch_fp0_regnum (gdbarch) != -1)
+ {
+ CORE_ADDR fpregs = regs + 22 * 4;
+ for (i = FR0_REGNUM; i <= FP_LAST_REGNUM; i++)
+ trad_frame_set_reg_addr (this_cache, i, fpregs + i * 4);
+ trad_frame_set_reg_addr (this_cache, FPSCR_REGNUM, fpregs + 32 * 4);
+ trad_frame_set_reg_addr (this_cache, FPUL_REGNUM, fpregs + 33 * 4);
+ }
+
+ /* Save a frame ID. */
+ trad_frame_set_id (this_cache, frame_id_build (base, func));
+}
+
+static void
+sh_linux_sigreturn_init (const struct tramp_frame *self,
+ struct frame_info *this_frame,
+ struct trad_frame_cache *this_cache,
+ CORE_ADDR func)
+{
+ /* SH 32-bit sigframe: sigcontext at start of sigframe,
+ registers start after a single 'oldmask' word. */
+ sh_linux_sigtramp_cache (this_frame, this_cache, func, 4);
+}
+
+static void
+sh_linux_rt_sigreturn_init (const struct tramp_frame *self,
+ struct frame_info *this_frame,
+ struct trad_frame_cache *this_cache,
+ CORE_ADDR func)
+{
+ /* SH 32-bit rt_sigframe: starts with a siginfo (128 bytes), then
+ we can find sigcontext embedded within a ucontext (offset 20 bytes).
+ Then registers start after a single 'oldmask' word. */
+ sh_linux_sigtramp_cache (this_frame, this_cache, func,
+ 128 /* sizeof (struct siginfo) */
+ + 20 /* offsetof (struct ucontext, uc_mcontext) */
+ + 4 /* oldmask word at start of sigcontext */);
+}
+
+/* Instruction patterns. */
+#define SH_MOVW 0x9305
+#define SH_TRAP 0xc300
+#define SH_OR_R0_R0 0x200b
+
+/* SH sigreturn syscall numbers. */
+#define SH_NR_SIGRETURN 0x0077
+#define SH_NR_RT_SIGRETURN 0x00ad
+
+static struct tramp_frame sh_linux_sigreturn_tramp_frame = {
+ SIGTRAMP_FRAME,
+ 2,
+ {
+ { SH_MOVW, 0xffff },
+ { SH_TRAP, 0xff00 }, /* #imm argument part filtered out. */
+ { SH_OR_R0_R0, 0xffff },
+ { SH_OR_R0_R0, 0xffff },
+ { SH_OR_R0_R0, 0xffff },
+ { SH_OR_R0_R0, 0xffff },
+ { SH_OR_R0_R0, 0xffff },
+ { SH_NR_SIGRETURN, 0xffff },
+ { TRAMP_SENTINEL_INSN }
+ },
+ sh_linux_sigreturn_init
+};
+
+static struct tramp_frame sh_linux_rt_sigreturn_tramp_frame = {
+ SIGTRAMP_FRAME,
+ 2,
+ {
+ { SH_MOVW, 0xffff },
+ { SH_TRAP, 0xff00 }, /* #imm argument part filtered out. */
+ { SH_OR_R0_R0, 0xffff },
+ { SH_OR_R0_R0, 0xffff },
+ { SH_OR_R0_R0, 0xffff },
+ { SH_OR_R0_R0, 0xffff },
+ { SH_OR_R0_R0, 0xffff },
+ { SH_NR_RT_SIGRETURN, 0xffff },
+ { TRAMP_SENTINEL_INSN }
+ },
+ sh_linux_rt_sigreturn_init
+};
+
static void
sh_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
@@ -84,13 +191,17 @@ sh_linux_init_abi (struct gdbarch_info i
set_gdbarch_fetch_tls_load_module_address (gdbarch,
svr4_fetch_objfile_link_map);

- /* Core files are supported for 32-bit SH only, at present. */
+ /* Core files and signal handler frame unwinding are supported for
+ 32-bit SH only, at present. */
if (info.bfd_arch_info->mach != bfd_mach_sh5)
{
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

tdep->core_gregmap = (struct sh_corefile_regmap *)gregs_table;
tdep->core_fpregmap = (struct sh_corefile_regmap *)fpregs_table;
+
+ tramp_frame_prepend_unwinder (gdbarch, &sh_linux_sigreturn_tramp_frame);
+ tramp_frame_prepend_unwinder (gdbarch, &sh_linux_rt_sigreturn_tramp_frame);
}
}