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Re: [offbyone RFC] Merge i386newframe
- From: Michal Ludvig <mludvig at suse dot cz>
- To: GDB Patches <gdb-patches at sources dot redhat dot com>
- Cc: Andrew Cagney <ac131313 at redhat dot com>,Mark Kettenis <kettenis at chello dot nl>
- Date: Fri, 14 Mar 2003 16:43:12 +0100
- Subject: Re: [offbyone RFC] Merge i386newframe
- Organization: SuSE CR
- References: <3E6FAF64.7070304@suse.cz>
Hi all,
I've reworked the merge a little to avoid the need to reorder
frame.c:get_prev_frame() and fixed the 'next' and 'return' bugs that
were in the prevoius one. Now it passes the testsuite even better than
the i386newframe code did :-)
I'm sorry I'm short of time to write more now.
Andrew and Mark, please look around the patch and tell me your opinions.
Have a nice weekend,
Michal Ludvig
--
* SuSE CR, s.r.o * mludvig at suse dot cz
* (+420) 296.545.373 * http://www.suse.cz
Index: i386-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/i386-tdep.c,v
retrieving revision 1.117
diff -u -p -r1.117 i386-tdep.c
--- i386-tdep.c 12 Mar 2003 16:50:44 -0000 1.117
+++ i386-tdep.c 14 Mar 2003 15:37:22 -0000
@@ -40,6 +40,7 @@
#include "reggroups.h"
#include "dummy-frame.h"
#include "osabi.h"
+#include "frame-unwind.h"
#include "i386-tdep.h"
#include "i387-tdep.h"
@@ -469,64 +470,8 @@ i386_get_frame_setup (CORE_ADDR pc)
return (-1);
}
-/* Signal trampolines don't have a meaningful frame. The frame
- pointer value we use is actually the frame pointer of the calling
- frame -- that is, the frame which was in progress when the signal
- trampoline was entered. GDB mostly treats this frame pointer value
- as a magic cookie. We detect the case of a signal trampoline by
- testing for get_frame_type() == SIGTRAMP_FRAME, which is set based
- on PC_IN_SIGTRAMP.
-
- When a signal trampoline is invoked from a frameless function, we
- essentially have two frameless functions in a row. In this case,
- we use the same magic cookie for three frames in a row. We detect
- this case by seeing whether the next frame is a SIGTRAMP_FRAME,
- and, if it does, checking whether the current frame is actually
- frameless. In this case, we need to get the PC by looking at the
- SP register value stored in the signal context.
-
- This should work in most cases except in horrible situations where
- a signal occurs just as we enter a function but before the frame
- has been set up. Incidentally, that's just what happens when we
- call a function from GDB with a signal pending (there's a test in
- the testsuite that makes this happen). Therefore we pretend that
- we have a frameless function if we're stopped at the start of a
- function. */
-
-/* Return non-zero if we're dealing with a frameless signal, that is,
- a signal trampoline invoked from a frameless function. */
-
-int
-i386_frameless_signal_p (struct frame_info *frame)
-{
- return (get_next_frame (frame)
- && get_frame_type (get_next_frame (frame)) == SIGTRAMP_FRAME
- && (frameless_look_for_prologue (frame)
- || get_frame_pc (frame) == get_pc_function_start (get_frame_pc (frame))));
-}
-
-/* Return the chain-pointer for FRAME. In the case of the i386, the
- frame's nominal address is the address of a 4-byte word containing
- the calling frame's address. */
-
-static CORE_ADDR
-i386_frame_chain (struct frame_info *frame)
-{
- if (pc_in_dummy_frame (get_frame_pc (frame)))
- return get_frame_base (frame);
-
- if (get_frame_type (frame) == SIGTRAMP_FRAME
- || i386_frameless_signal_p (frame))
- return get_frame_base (frame);
-
- if (! inside_entry_file (get_frame_pc (frame)))
- return read_memory_unsigned_integer (get_frame_base (frame), 4);
-
- return 0;
-}
-
/* Determine whether the function invocation represented by FRAME does
- not have a from on the stack associated with it. If it does not,
+ not have a frame on the stack associated with it. If it does not,
return non-zero, otherwise return zero. */
static int
@@ -538,66 +483,16 @@ i386_frameless_function_invocation (stru
return frameless_look_for_prologue (frame);
}
-/* Assuming FRAME is for a sigtramp routine, return the saved program
- counter. */
-
-static CORE_ADDR
-i386_sigtramp_saved_pc (struct frame_info *frame)
-{
- struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
- CORE_ADDR addr;
-
- addr = tdep->sigcontext_addr (frame);
- return read_memory_unsigned_integer (addr + tdep->sc_pc_offset, 4);
-}
-
-/* Assuming FRAME is for a sigtramp routine, return the saved stack
- pointer. */
-
-static CORE_ADDR
-i386_sigtramp_saved_sp (struct frame_info *frame)
-{
- struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
- CORE_ADDR addr;
-
- addr = tdep->sigcontext_addr (frame);
- return read_memory_unsigned_integer (addr + tdep->sc_sp_offset, 4);
-}
-
-/* Return the saved program counter for FRAME. */
-
-static CORE_ADDR
-i386_frame_saved_pc (struct frame_info *frame)
-{
- if (pc_in_dummy_frame (get_frame_pc (frame)))
- {
- ULONGEST pc;
-
- frame_unwind_unsigned_register (frame, PC_REGNUM, &pc);
- return pc;
- }
-
- if (get_frame_type (frame) == SIGTRAMP_FRAME)
- return i386_sigtramp_saved_pc (frame);
-
- if (i386_frameless_signal_p (frame))
- {
- CORE_ADDR sp = i386_sigtramp_saved_sp (get_next_frame (frame));
- return read_memory_unsigned_integer (sp, 4);
- }
-
- return read_memory_unsigned_integer (get_frame_base (frame) + 4, 4);
-}
-
/* Immediately after a function call, return the saved pc. */
static CORE_ADDR
i386_saved_pc_after_call (struct frame_info *frame)
{
- if (get_frame_type (frame) == SIGTRAMP_FRAME)
- return i386_sigtramp_saved_pc (frame);
+ char buf[4];
- return read_memory_unsigned_integer (read_register (SP_REGNUM), 4);
+ /* Our frame unwinder handles this just fine. */
+ frame_unwind_register (frame, PC_REGNUM, buf);
+ return extract_address (buf, 4);
}
/* Return number of args passed to a frame.
@@ -674,72 +569,6 @@ i386_frame_num_args (struct frame_info *
#endif
}
-/* Parse the first few instructions the function to see what registers
- were stored.
-
- We handle these cases:
-
- The startup sequence can be at the start of the function, or the
- function can start with a branch to startup code at the end.
-
- %ebp can be set up with either the 'enter' instruction, or "pushl
- %ebp, movl %esp, %ebp" (`enter' is too slow to be useful, but was
- once used in the System V compiler).
-
- Local space is allocated just below the saved %ebp by either the
- 'enter' instruction, or by "subl $<size>, %esp". 'enter' has a 16
- bit unsigned argument for space to allocate, and the 'addl'
- instruction could have either a signed byte, or 32 bit immediate.
-
- Next, the registers used by this function are pushed. With the
- System V compiler they will always be in the order: %edi, %esi,
- %ebx (and sometimes a harmless bug causes it to also save but not
- restore %eax); however, the code below is willing to see the pushes
- in any order, and will handle up to 8 of them.
-
- If the setup sequence is at the end of the function, then the next
- instruction will be a branch back to the start. */
-
-static void
-i386_frame_init_saved_regs (struct frame_info *fip)
-{
- long locals = -1;
- unsigned char op;
- CORE_ADDR addr;
- CORE_ADDR pc;
- int i;
-
- if (get_frame_saved_regs (fip))
- return;
-
- frame_saved_regs_zalloc (fip);
-
- pc = get_pc_function_start (get_frame_pc (fip));
- if (pc != 0)
- locals = i386_get_frame_setup (pc);
-
- if (locals >= 0)
- {
- addr = get_frame_base (fip) - 4 - locals;
- for (i = 0; i < 8; i++)
- {
- op = codestream_get ();
- if (op < 0x50 || op > 0x57)
- break;
-#ifdef I386_REGNO_TO_SYMMETRY
- /* Dynix uses different internal numbering. Ick. */
- get_frame_saved_regs (fip)[I386_REGNO_TO_SYMMETRY (op - 0x50)] = addr;
-#else
- get_frame_saved_regs (fip)[op - 0x50] = addr;
-#endif
- addr -= 4;
- }
- }
-
- get_frame_saved_regs (fip)[PC_REGNUM] = get_frame_base (fip) + 4;
- get_frame_saved_regs (fip)[FP_REGNUM] = get_frame_base (fip);
-}
-
/* Return PC of first real instruction. */
static CORE_ADDR
@@ -855,37 +684,323 @@ i386_push_return_address (CORE_ADDR pc,
write_memory (sp - 4, buf, 4);
return sp - 4;
}
+
+#define regcache_cooked_write_unsigned regcache_raw_write_unsigned
-static void
-i386_do_pop_frame (struct frame_info *frame)
+#ifdef I386_REGNO_TO_SYMMETRY
+#error "The Sequent Symmetry is no longer supported."
+#endif
+
+/* According to the System V ABI, the registers %ebp, %ebx, %edi, %esi
+ and %esp "belong" to the calling function. */
+
+/* The maximum number of saved registers. This should include all
+ registers mentioned above, and %eip. */
+#define I386_NUM_SAVED_REGISTERS 9
+
+struct i386_frame_cache
+{
+ CORE_ADDR saved_regs[I386_NUM_SAVED_REGISTERS];
+ CORE_ADDR saved_sp;
+ CORE_ADDR return_pc;
+ CORE_ADDR base;
+ int frameless;
+};
+
+/* Parse the first few instructions the function to see what registers
+ were stored.
+
+ We handle these cases:
+
+ The startup sequence can be at the start of the function, or the
+ function can start with a branch to startup code at the end.
+
+ %ebp can be set up with either the 'enter' instruction, or "pushl
+ %ebp, movl %esp, %ebp" (`enter' is too slow to be useful, but was
+ once used in the System V compiler).
+
+ Local space is allocated just below the saved %ebp by either the
+ 'enter' instruction, or by "subl $<size>, %esp". 'enter' has a 16
+ bit unsigned argument for space to allocate, and the 'addl'
+ instruction could have either a signed byte, or 32 bit immediate.
+
+ Next, the registers used by this function are pushed. With the
+ System V compiler they will always be in the order: %edi, %esi,
+ %ebx (and sometimes a harmless bug causes it to also save but not
+ restore %eax); however, the code below is willing to see the pushes
+ in any order, and will handle up to 8 of them.
+
+ If the setup sequence is at the end of the function, then the next
+ instruction will be a branch back to the start. */
+
+static struct i386_frame_cache *
+i386_frame_cache (struct frame_info *frame, void **cachep)
{
- CORE_ADDR fp;
- int regnum;
- char regbuf[I386_MAX_REGISTER_SIZE];
+ struct i386_frame_cache *cache;
+ CORE_ADDR pc, start_pc;
+
+ if (*cachep)
+ return *cachep;
+
+ cache = FRAME_OBSTACK_ZALLOC (struct i386_frame_cache);
+
+ pc = frame_pc_unwind (frame);
+ start_pc = get_pc_function_start (pc);
- fp = get_frame_base (frame);
- i386_frame_init_saved_regs (frame);
+ long locals = -1;
+
+ if (start_pc != 0)
+ locals = i386_get_frame_setup (start_pc);
- for (regnum = 0; regnum < NUM_REGS; regnum++)
+ if (locals >= 0 && pc > start_pc)
{
+ ULONGEST fp;
CORE_ADDR addr;
- addr = get_frame_saved_regs (frame)[regnum];
- if (addr)
+ unsigned char op;
+ int i;
+
+ frame_unwind_unsigned_register (frame, FP_REGNUM, &fp);
+ cache->base = fp;
+
+ addr = fp - 4 - locals;
+ for (i = 0; i < I386_NUM_SAVED_REGISTERS; i++)
+ {
+ op = codestream_get ();
+ if (op < 0x50 || op > 0x57)
+ break;
+
+ cache->saved_regs[op - 0x50] = addr;
+ addr -= 4;
+ }
+
+ cache->saved_regs[PC_REGNUM] = fp + 4;
+ cache->saved_regs[FP_REGNUM] = fp;
+ cache->saved_sp = fp + 8;
+ }
+ else
+ {
+ ULONGEST sp;
+
+ /* This function is either frameless or we're at the start
+ of the function and this function's frame hasn't been
+ setup yet. In the latter case only %eip and %esp have
+ changed, and we can determine their previous values. We
+ pretend we can do the same in the former case. */
+ cache->frameless = 1;
+
+ frame_unwind_unsigned_register (frame, SP_REGNUM, &sp);
+ cache->saved_regs[PC_REGNUM] = sp;
+ cache->saved_sp = cache->saved_regs[PC_REGNUM] + 4;
+ cache->base = sp;
+ }
+
+ *cachep = cache;
+ return cache;
+}
+
+static CORE_ADDR
+i386_frame_pc_unwind (struct frame_info *frame, void **cachep)
+{
+ struct i386_frame_cache *cache = i386_frame_cache (frame, cachep);
+
+ if (cache->return_pc == 0)
+ {
+ char buf[4];
+
+ frame_unwind_register (frame, PC_REGNUM, buf);
+ cache->return_pc = extract_address (buf, 4);
+ }
+
+ return cache->return_pc;
+}
+
+static CORE_ADDR
+i386_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
+{
+ ULONGEST pc;
+ frame_unwind_unsigned_register (next_frame, PC_REGNUM, &pc);
+ return (CORE_ADDR) pc;
+}
+
+static void
+i386_frame_this_id (struct frame_info *next_frame,
+ void **cachep,
+ struct frame_id *this_id)
+{
+ CORE_ADDR pc;
+ ULONGEST base;
+
+ gdb_assert (this_id != NULL);
+
+ *this_id = null_frame_id;
+
+ pc = frame_pc_unwind (next_frame);
+
+ frame_unwind_unsigned_register (next_frame, FP_REGNUM, &base);
+
+ if (frame_relative_level (next_frame) >= 0
+ && get_frame_type (next_frame) != DUMMY_FRAME
+ && get_frame_id (next_frame).pc == pc
+ && get_frame_id (next_frame).base == base)
+ return;
+
+ this_id->pc = pc;
+ this_id->base = base;
+}
+
+static void
+i386_frame_register_unwind (struct frame_info *frame, void **cachep,
+ int regnum, int *optimizedp,
+ enum lval_type *lvalp, CORE_ADDR *addrp,
+ int *realnump, void *valuep)
+{
+ /* FIXME: kettenis/20030302: I don't understand why the cache isn't
+ already initialized. */
+ struct i386_frame_cache *cache = i386_frame_cache (frame, cachep);
+
+ gdb_assert (cache);
+ gdb_assert (regnum >= 0);
+
+ if (regnum == PC_REGNUM)
+ {
+ CORE_ADDR pc;
+ *optimizedp = 0;
+ *lvalp = not_lval;
+ *addrp = 0;
+ *realnump = -1;
+ pc = i386_frame_pc_unwind (frame, cachep);
+ if (valuep)
+ store_address (valuep, 4, pc);
+ }
+
+ if (regnum < I386_NUM_SAVED_REGISTERS && cache->saved_regs[regnum] != 0)
+ {
+ *optimizedp = 0;
+ *lvalp = lval_memory;
+ *addrp = cache->saved_regs[regnum];
+ *realnump = -1;
+ if (valuep)
{
- read_memory (addr, regbuf, REGISTER_RAW_SIZE (regnum));
- deprecated_write_register_gen (regnum, regbuf);
+ /* Read the value in from memory. */
+ read_memory (*addrp, valuep,
+ register_size (current_gdbarch, regnum));
}
+ return;
}
- write_register (FP_REGNUM, read_memory_integer (fp, 4));
- write_register (PC_REGNUM, read_memory_integer (fp + 4, 4));
- write_register (SP_REGNUM, fp + 8);
- flush_cached_frames ();
+
+ frame_register (frame, regnum, optimizedp, lvalp, addrp, realnump, valuep);
+}
+
+static struct i386_frame_cache *
+i386_sigtramp_cache (struct frame_info *frame, void **cachep)
+{
+ struct i386_frame_cache *cache;
+ CORE_ADDR pc, start_pc, addr;
+ struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
+ int sc_offset, regnum;
+
+ if (*cachep)
+ return *cachep;
+
+ cache = FRAME_OBSTACK_ZALLOC (struct i386_frame_cache);
+
+ pc = frame_pc_unwind (frame);
+ start_pc = get_pc_function_start (pc);
+ addr = tdep->sigcontext_addr (frame->prev);
+
+ for (regnum=0; regnum<=PS_REGNUM; regnum++)
+ {
+ /* See <asm/sigcontext.h> for details on how registers are stored
+ in the sigcontext. */
+ if (regnum < PC_REGNUM)
+ sc_offset = (11 - regnum);
+ else if (regnum == PC_REGNUM)
+ sc_offset = 14;
+ else if (regnum == PS_REGNUM)
+ sc_offset = 16;
+ else
+ break;
+
+ sc_offset *= 4;
+
+ if (regnum < sizeof (cache->saved_regs))
+ cache->saved_regs[regnum] = addr + sc_offset;
+ }
+
+ cache->base = addr;
+
+ *cachep = cache;
+ return cache;
}
static void
-i386_pop_frame (void)
+i386_sigtramp_register_unwind (struct frame_info *frame, void **cachep,
+ int regnum, int *optimizedp,
+ enum lval_type *lvalp, CORE_ADDR *addrp,
+ int *realnump, void *valuep)
+{
+ struct i386_frame_cache *cache = i386_sigtramp_cache (frame, cachep);
+
+ gdb_assert (cache);
+ gdb_assert (regnum >= 0);
+
+ if (regnum < I386_NUM_SAVED_REGISTERS && cache->saved_regs[regnum] != 0)
+ {
+ *optimizedp = 0;
+ *lvalp = lval_memory;
+ *addrp = cache->saved_regs[regnum];
+ *realnump = -1;
+ if (valuep)
+ read_memory (*addrp, valuep,
+ register_size (current_gdbarch, regnum));
+ return;
+ }
+
+ /* Fall back for non-saved registers. */
+ frame_register (frame, regnum, optimizedp, lvalp, addrp, realnump, valuep);
+}
+
+static struct frame_unwind i386_sigtramp_unwind = {
+ i386_frame_this_id,
+ i386_sigtramp_register_unwind
+};
+
+static struct frame_unwind i386_frame_unwind = {
+ i386_frame_this_id,
+ i386_frame_register_unwind
+};
+
+const struct frame_unwind *
+i386_frame_p (CORE_ADDR pc)
+{
+ if (gdbarch_pc_in_sigtramp (current_gdbarch, pc, NULL))
+ return &i386_sigtramp_unwind;
+ else
+ return &i386_frame_unwind;
+}
+
+static struct frame_id
+i386_unwind_dummy_id (struct gdbarch *gdbarch, struct frame_info *next_frame)
+{
+ struct frame_id id;
+ ULONGEST base;
+
+ id.pc = frame_pc_unwind (next_frame);
+ frame_unwind_unsigned_register (next_frame, FP_REGNUM, &base);
+ id.base = base;
+ return id;
+}
+
+static void
+i386_save_dummy_frame_tos (CORE_ADDR sp)
{
- generic_pop_current_frame (i386_do_pop_frame);
+ /* We can't use the saved top-of-stack to find the right dummy frame
+ when unwinding, since we can't reconstruct it properly if the
+ dummy frame is the innermost frame. To circumvent this, we fake
+ a frame pointer here. */
+
+ regcache_cooked_write_unsigned (current_regcache, FP_REGNUM, sp);
+ generic_save_dummy_frame_tos (sp);
}
@@ -1312,7 +1427,13 @@ i386_pe_skip_trampoline_code (CORE_ADDR
static int
i386_pc_in_sigtramp (CORE_ADDR pc, char *name)
{
- return (name && strcmp ("_sigtramp", name) == 0);
+ char *pname;
+ if (name)
+ pname = name;
+ else
+ find_pc_partial_function (pc, &pname, NULL, NULL);
+
+ return (name && strcmp ("_sigtramp", pname) == 0);
}
@@ -1506,10 +1627,6 @@ i386_gdbarch_init (struct gdbarch_info i
tdep = XMALLOC (struct gdbarch_tdep);
gdbarch = gdbarch_alloc (&info, tdep);
- /* NOTE: cagney/2002-12-06: This can be deleted when this arch is
- ready to unwind the PC first (see frame.c:get_prev_frame()). */
- set_gdbarch_deprecated_init_frame_pc (gdbarch, init_frame_pc_default);
-
/* The i386 default settings don't include the SSE registers.
FIXME: kettenis/20020614: They do include the FPU registers for
now, which probably is not quite right. */
@@ -1591,14 +1708,12 @@ i386_gdbarch_init (struct gdbarch_info i
set_gdbarch_extract_return_value (gdbarch, i386_extract_return_value);
set_gdbarch_push_arguments (gdbarch, i386_push_arguments);
set_gdbarch_push_return_address (gdbarch, i386_push_return_address);
- set_gdbarch_pop_frame (gdbarch, i386_pop_frame);
set_gdbarch_store_struct_return (gdbarch, i386_store_struct_return);
set_gdbarch_store_return_value (gdbarch, i386_store_return_value);
set_gdbarch_extract_struct_value_address (gdbarch,
i386_extract_struct_value_address);
set_gdbarch_use_struct_convention (gdbarch, i386_use_struct_convention);
- set_gdbarch_deprecated_frame_init_saved_regs (gdbarch, i386_frame_init_saved_regs);
set_gdbarch_skip_prologue (gdbarch, i386_skip_prologue);
/* Stack grows downward. */
@@ -1608,16 +1723,9 @@ i386_gdbarch_init (struct gdbarch_info i
set_gdbarch_decr_pc_after_break (gdbarch, 1);
set_gdbarch_function_start_offset (gdbarch, 0);
- /* The following redefines make backtracing through sigtramp work.
- They manufacture a fake sigtramp frame and obtain the saved pc in
- sigtramp from the sigcontext structure which is pushed by the
- kernel on the user stack, along with a pointer to it. */
-
set_gdbarch_frame_args_skip (gdbarch, 8);
set_gdbarch_frameless_function_invocation (gdbarch,
i386_frameless_function_invocation);
- set_gdbarch_frame_chain (gdbarch, i386_frame_chain);
- set_gdbarch_deprecated_frame_saved_pc (gdbarch, i386_frame_saved_pc);
set_gdbarch_saved_pc_after_call (gdbarch, i386_saved_pc_after_call);
set_gdbarch_frame_num_args (gdbarch, i386_frame_num_args);
set_gdbarch_pc_in_sigtramp (gdbarch, i386_pc_in_sigtramp);
@@ -1629,12 +1737,19 @@ i386_gdbarch_init (struct gdbarch_info i
set_gdbarch_print_insn (gdbarch, i386_print_insn);
+ set_gdbarch_unwind_dummy_id (gdbarch, i386_unwind_dummy_id);
+ set_gdbarch_save_dummy_frame_tos (gdbarch, i386_save_dummy_frame_tos);
+
+ set_gdbarch_unwind_pc (gdbarch, i386_unwind_pc);
+
/* Add the i386 register groups. */
i386_add_reggroups (gdbarch);
set_gdbarch_register_reggroup_p (gdbarch, i386_register_reggroup_p);
/* Hook in ABI-specific overrides, if they have been registered. */
gdbarch_init_osabi (info, gdbarch);
+
+ frame_unwind_append_predicate (gdbarch, i386_frame_p);
return gdbarch;
}