[PUSHED v2 1/2] arc: Add support for signal handlers
Shahab Vahedi
shahab.vahedi@gmail.com
Tue Dec 22 11:13:39 GMT 2020
From: Anton Kolesov <Anton.Kolesov@synopsys.com>
This patch adds the necessary infrastructure to handle signal frames for
ARC architecture. It is fairly similar to what any other architecture
would have. Linux specific parts will be in a separate patch.
v2 [1]:
- Make the logic of "arc_sigtramp_frame_sniffer ()" simpler.
[1] Tom's remark for the first version
https://sourceware.org/pipermail/gdb-patches/2020-November/173221.html
gdb/ChangeLog:
* arc-tdep.c (arc_make_sigtramp_frame_cache): New function.
(arc_sigtramp_frame_this_id): Likewise.
(arc_sigtramp_frame_prev_register): Likewise.
(arc_sigtramp_frame_sniffer): Likewise.
(arc_siftramp_frame_unwind): New global variable.
(arc_gdbarch_init): Use sigtramp capabilities.
(arc_dump_tdep): Print sigtramp fields.
* arc-tdep.h (gdbarch_tdep): Add sigtramp fields.
---
gdb/arc-tdep.c | 123 +++++++++++++++++++++++++++++++++++++++++++++++++
gdb/arc-tdep.h | 13 ++++++
2 files changed, 136 insertions(+)
diff --git a/gdb/arc-tdep.c b/gdb/arc-tdep.c
index bcc73590087..2dced431452 100644
--- a/gdb/arc-tdep.c
+++ b/gdb/arc-tdep.c
@@ -1843,6 +1843,104 @@ arc_dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
reg->how = DWARF2_FRAME_REG_CFA;
}
+/* Signal trampoline frame unwinder. Allows frame unwinding to happen
+ from within signal handlers. */
+
+static struct arc_frame_cache *
+arc_make_sigtramp_frame_cache (struct frame_info *this_frame)
+{
+ if (arc_debug)
+ debug_printf ("arc: sigtramp_frame_cache\n");
+
+ struct gdbarch_tdep *tdep = gdbarch_tdep (get_frame_arch (this_frame));
+
+ /* Allocate new frame cache instance and space for saved register info. */
+ struct arc_frame_cache *cache = FRAME_OBSTACK_ZALLOC (struct arc_frame_cache);
+ cache->saved_regs = trad_frame_alloc_saved_regs (this_frame);
+
+ /* Get the stack pointer and use it as the frame base. */
+ cache->prev_sp = arc_frame_base_address (this_frame, NULL);
+
+ /* If the ARC-private target-dependent info doesn't have a table of
+ offsets of saved register contents within an OS signal context
+ structure, then there is nothing to analyze. */
+ if (tdep->sc_reg_offset == NULL)
+ return cache;
+
+ /* Find the address of the sigcontext structure. */
+ CORE_ADDR addr = tdep->sigcontext_addr (this_frame);
+
+ /* For each register, if its contents have been saved within the
+ sigcontext structure, determine the address of those contents. */
+ gdb_assert (tdep->sc_num_regs <= (ARC_LAST_REGNUM + 1));
+ for (int i = 0; i < tdep->sc_num_regs; i++)
+ {
+ if (tdep->sc_reg_offset[i] != ARC_OFFSET_NO_REGISTER)
+ cache->saved_regs[i].addr = addr + tdep->sc_reg_offset[i];
+ }
+
+ return cache;
+}
+
+/* Implement the "this_id" frame_unwind method for signal trampoline
+ frames. */
+
+static void
+arc_sigtramp_frame_this_id (struct frame_info *this_frame,
+ void **this_cache, struct frame_id *this_id)
+{
+ if (arc_debug)
+ debug_printf ("arc: sigtramp_frame_this_id\n");
+
+ if (*this_cache == NULL)
+ *this_cache = arc_make_sigtramp_frame_cache (this_frame);
+
+ struct gdbarch *gdbarch = get_frame_arch (this_frame);
+ struct arc_frame_cache *cache = (struct arc_frame_cache *) *this_cache;
+ CORE_ADDR stack_addr = cache->prev_sp;
+ CORE_ADDR code_addr
+ = get_frame_register_unsigned (this_frame, gdbarch_pc_regnum (gdbarch));
+ *this_id = frame_id_build (stack_addr, code_addr);
+}
+
+/* Get a register from a signal handler frame. */
+
+static struct value *
+arc_sigtramp_frame_prev_register (struct frame_info *this_frame,
+ void **this_cache, int regnum)
+{
+ if (arc_debug)
+ debug_printf ("arc: sigtramp_frame_prev_register (regnum = %d)\n", regnum);
+
+ /* Make sure we've initialized the cache. */
+ if (*this_cache == NULL)
+ *this_cache = arc_make_sigtramp_frame_cache (this_frame);
+
+ struct arc_frame_cache *cache = (struct arc_frame_cache *) *this_cache;
+ return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum);
+}
+
+/* Frame sniffer for signal handler frame. Only recognize a frame if we
+ have a sigcontext_addr handler in the target dependency. */
+
+static int
+arc_sigtramp_frame_sniffer (const struct frame_unwind *self,
+ struct frame_info *this_frame,
+ void **this_cache)
+{
+ struct gdbarch_tdep *tdep;
+
+ if (arc_debug)
+ debug_printf ("arc: sigtramp_frame_sniffer\n");
+
+ tdep = gdbarch_tdep (get_frame_arch (this_frame));
+
+ /* If we have a sigcontext_addr handler, then just return 1 (same as the
+ "default_frame_sniffer ()"). */
+ return (tdep->sigcontext_addr != NULL && tdep->is_sigtramp != NULL
+ && tdep->is_sigtramp (this_frame));
+}
+
/* Structure defining the ARC ordinary frame unwind functions. Since we are
the fallback unwinder, we use the default frame sniffer, which always
accepts the frame. */
@@ -1858,6 +1956,21 @@ static const struct frame_unwind arc_frame_unwind = {
NULL
};
+/* Structure defining the ARC signal frame unwind functions. Custom
+ sniffer is used, because this frame must be accepted only in the right
+ context. */
+
+static const struct frame_unwind arc_sigtramp_frame_unwind = {
+ SIGTRAMP_FRAME,
+ default_frame_unwind_stop_reason,
+ arc_sigtramp_frame_this_id,
+ arc_sigtramp_frame_prev_register,
+ NULL,
+ arc_sigtramp_frame_sniffer,
+ NULL,
+ NULL
+};
+
static const struct frame_base arc_normal_base = {
&arc_frame_unwind,
@@ -2271,6 +2384,7 @@ arc_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
/* Frame unwinders and sniffers. */
dwarf2_frame_set_init_reg (gdbarch, arc_dwarf2_frame_init_reg);
dwarf2_append_unwinders (gdbarch);
+ frame_unwind_append_unwinder (gdbarch, &arc_sigtramp_frame_unwind);
frame_unwind_append_unwinder (gdbarch, &arc_frame_unwind);
frame_base_set_default (gdbarch, &arc_normal_base);
@@ -2349,6 +2463,15 @@ arc_dump_tdep (struct gdbarch *gdbarch, struct ui_file *file)
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
fprintf_unfiltered (file, "arc_dump_tdep: jb_pc = %i\n", tdep->jb_pc);
+
+ fprintf_unfiltered (file, "arc_dump_tdep: is_sigtramp = <%s>\n",
+ host_address_to_string (tdep->is_sigtramp));
+ fprintf_unfiltered (file, "arc_dump_tdep: sigcontext_addr = <%s>\n",
+ host_address_to_string (tdep->sigcontext_addr));
+ fprintf_unfiltered (file, "arc_dump_tdep: sc_reg_offset = <%s>\n",
+ host_address_to_string (tdep->sc_reg_offset));
+ fprintf_unfiltered (file, "arc_dump_tdep: sc_num_regs = %d\n",
+ tdep->sc_num_regs);
}
/* This command accepts single argument - address of instruction to
diff --git a/gdb/arc-tdep.h b/gdb/arc-tdep.h
index 09fcbeab9c7..5ee5cf85c6c 100644
--- a/gdb/arc-tdep.h
+++ b/gdb/arc-tdep.h
@@ -124,6 +124,19 @@ struct gdbarch_tdep
/* Whether target has hardware (aka zero-delay) loops. */
bool has_hw_loops;
+
+ /* Detect sigtramp. */
+ bool (*is_sigtramp) (struct frame_info *);
+
+ /* Get address of sigcontext for sigtramp. */
+ CORE_ADDR (*sigcontext_addr) (struct frame_info *);
+
+ /* Offset of registers in `struct sigcontext'. */
+ const int *sc_reg_offset;
+
+ /* Number of registers in sc_reg_offsets. Most likely a ARC_LAST_REGNUM,
+ but in theory it could be less, so it is kept separate. */
+ int sc_num_regs;
};
/* Utility functions used by other ARC-specific modules. */
--
2.29.2
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