In entry-values.exp, we have a test where the entry value of 'j' is
unavailable, so it is expected that printing j@entry yields
"<unavailable>". However, the actual output is:
(gdb) frame
#0 0x0000000000400540 in foo (i=0, i@entry=2, j=2, j@entry=<error reading variable: Cannot access memory at address 0x6009e8>)
The error is thrown here:
#0 throw_it (reason=RETURN_ERROR, error=MEMORY_ERROR, fmt=0x8cd550 "Cannot access memory at address %s", ap=0x7fffffffc8e8) at ../../src/gdb/exceptions.c:373
#1 0x00000000005e2f9c in throw_error (error=MEMORY_ERROR, fmt=0x8cd550 "Cannot access memory at address %s") at ../../src/gdb/exceptions.c:422
#2 0x0000000000673a5f in memory_error (status=5, memaddr=6293992) at ../../src/gdb/corefile.c:204
#3 0x0000000000673aea in read_memory (memaddr=6293992, myaddr=0x7fffffffca60 "\200\316\377\377\377\177", len=4) at ../../src/gdb/corefile.c:223
#4 0x00000000006784d1 in dwarf_expr_read_mem (baton=0x7fffffffcd50, buf=0x7fffffffca60 "\200\316\377\377\377\177", addr=6293992, len=4) at ../../src/gdb/dwarf2loc.c:334
#5 0x000000000067645e in execute_stack_op (ctx=0x1409480, op_ptr=0x7fffffffce87 "\237<\005@", op_end=0x7fffffffce88 "<\005@") at ../../src/gdb/dwarf2expr.c:1045
#6 0x0000000000674e29 in dwarf_expr_eval (ctx=0x1409480, addr=0x7fffffffce80 "\003\350\t`", len=8) at ../../src/gdb/dwarf2expr.c:364
#7 0x000000000067c5b2 in dwarf2_evaluate_loc_desc_full (type=0x10876d0, frame=0xd8ecc0, data=0x7fffffffce80 "\003\350\t`", size=8, per_cu=0xf24c40, byte_offset=0)
at ../../src/gdb/dwarf2loc.c:2236
#8 0x000000000067cc65 in dwarf2_evaluate_loc_desc (type=0x10876d0, frame=0xd8ecc0, data=0x7fffffffce80 "\003\350\t`", size=8, per_cu=0xf24c40)
at ../../src/gdb/dwarf2loc.c:2407
#9 0x000000000067a5d4 in dwarf_entry_parameter_to_value (parameter=0x13a7960, deref_size=
18446744073709551615, type=0x10876d0, caller_frame=0xd8ecc0, per_cu=0xf24c40)
at ../../src/gdb/dwarf2loc.c:1160
#10 0x000000000067a962 in value_of_dwarf_reg_entry (type=0x10876d0, frame=0xd8de70, kind=CALL_SITE_PARAMETER_DWARF_REG, kind_u=...) at ../../src/gdb/dwarf2loc.c:1310
#11 0x000000000067aaca in value_of_dwarf_block_entry (type=0x10876d0, frame=0xd8de70, block=0xf1c2d4 "Q", block_len=1) at ../../src/gdb/dwarf2loc.c:1363
#12 0x000000000067e7c9 in locexpr_read_variable_at_entry (symbol=0x13a7540, frame=0xd8de70) at ../../src/gdb/dwarf2loc.c:3326
#13 0x00000000005daab6 in read_frame_arg (sym=0x13a7540, frame=0xd8de70, argp=0x7fffffffd0e0, entryargp=0x7fffffffd100) at ../../src/gdb/stack.c:362
#14 0x00000000005db384 in print_frame_args (func=0x13a7470, frame=0xd8de70, num=-1, stream=0xea3890) at ../../src/gdb/stack.c:669
#15 0x00000000005dc338 in print_frame (frame=0xd8de70, print_level=1, print_what=SRC_AND_LOC, print_args=1, sal=...) at ../../src/gdb/stack.c:1199
#16 0x00000000005db8ee in print_frame_info (frame=0xd8de70, print_level=1, print_what=SRC_AND_LOC, print_args=1) at ../../src/gdb/stack.c:851
#17 0x00000000005da2bb in print_stack_frame (frame=0xd8de70, print_level=1, print_what=SRC_AND_LOC) at ../../src/gdb/stack.c:169
#18 0x00000000005de236 in frame_command (level_exp=0x0, from_tty=1) at ../../src/gdb/stack.c:2265
dwarf2_evaluate_loc_desc_full (frame #7) knows to handle
NOT_AVAILABLE_ERROR errors, but read_memory always throws
a generic error.
Presently, only the value machinery knows to handle unavailable
memory. We need to push the awareness down to the target_xfer layer,
making it return a finer grained error indication. We can only return
a generic -1 nowadays, which leaves the upper layers with no clue on
why the xfer failed. Use target_xfer_partial directly, rather than
propagating the error through target_read_memory so as to get a better
address to display in the error message.
(target_read_memory & friends build on top of target_read (thus the
target_xfer machinery), but turn all errors to EIO, an errno value. I
think this is a mistake, and we'd better convert all these to return a
target_xfer_error too, but that can be done separately. I looked
around a bit over memory_error calls, and the need to handle random
errno values, other than the EIOs gdb itself hardcodes, probably comes
(only) from deprecated_xfer_memory, which uses errno for error
indication, but I didn't look exhaustively. We should really get rid
of deprecated_xfer_memory and of passing down errno values as error
indication in target_read & friends methods).
Tested on x86_64 Fedora 17, native and gdbserver. Fixes the test in
the PR, which will be added to the testsuite later.
gdb/
2013-08-22 Pedro Alves <palves@redhat.com>
PR gdb/15871
* corefile.c (target_xfer_memory_error): New function.
(memory_error): Defer EIO to target_memory_error.
(read_memory): Use target_xfer_partial, and handle finer-grained
target xfer errors.
* target.c (target_xfer_error_to_string): New function.
(memory_xfer_partial_1): If memory is known to be
unavailable, return TARGET_XFER_E_UNAVAILABLE instead of -1.
(target_xfer_partial): Make extern.
* target.h (enum target_xfer_error): New enum.
(target_xfer_error_to_string): Declare function.
(target_xfer_partial): Declare function.
(struct target_ops) <xfer_partial>: Adjust describing comment.
+2013-08-22 Pedro Alves <palves@redhat.com>
+
+ PR gdb/15871
+ * corefile.c (target_xfer_memory_error): New function.
+ (memory_error): Defer EIO to target_memory_error.
+ (read_memory): Use target_xfer_partial, and handle finer-grained
+ target xfer errors.
+ * target.c (target_xfer_error_to_string): New function.
+ (memory_xfer_partial_1): If memory is known to be
+ unavailable, return TARGET_XFER_E_UNAVAILABLE instead of -1.
+ (target_xfer_partial): Make extern.
+ * target.h (enum target_xfer_error): New enum.
+ (target_xfer_error_to_string): Declare function.
+ (target_xfer_partial): Declare function.
+ (struct target_ops) <xfer_partial>: Adjust describing comment.
+
2013-08-22 Alan Modra <amodra@gmail.com>
* configure.host: Support powerpc64le-linux and powerpcle-linux hosts.
}
\f
+/* Report a target xfer memory error by throwing a suitable
+ exception. */
+
+static void
+target_xfer_memory_error (enum target_xfer_error err, CORE_ADDR memaddr)
+{
+ switch (err)
+ {
+ case TARGET_XFER_E_IO:
+ /* Actually, address between memaddr and memaddr + len was out of
+ bounds. */
+ throw_error (MEMORY_ERROR,
+ _("Cannot access memory at address %s"),
+ paddress (target_gdbarch (), memaddr));
+ case TARGET_XFER_E_UNAVAILABLE:
+ throw_error (NOT_AVAILABLE_ERROR,
+ _("Memory at address %s unavailable."),
+ paddress (target_gdbarch (), memaddr));
+ default:
+ internal_error (__FILE__, __LINE__,
+ "unhandled target_xfer_error: %s (%s)",
+ target_xfer_error_to_string (err),
+ plongest (err));
+ }
+}
+
/* Report a memory error by throwing a MEMORY_ERROR error. */
void
memory_error (int status, CORE_ADDR memaddr)
{
if (status == EIO)
- /* Actually, address between memaddr and memaddr + len was out of
- bounds. */
- throw_error (MEMORY_ERROR,
- _("Cannot access memory at address %s"),
- paddress (target_gdbarch (), memaddr));
+ target_xfer_memory_error (TARGET_XFER_E_IO, memaddr);
else
throw_error (MEMORY_ERROR,
_("Error accessing memory address %s: %s."),
void
read_memory (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
{
- int status;
+ LONGEST xfered = 0;
- status = target_read_memory (memaddr, myaddr, len);
- if (status != 0)
- memory_error (status, memaddr);
+ while (xfered < len)
+ {
+ LONGEST xfer = target_xfer_partial (current_target.beneath,
+ TARGET_OBJECT_MEMORY, NULL,
+ myaddr + xfered, NULL,
+ memaddr + xfered, len - xfered);
+
+ if (xfer == 0)
+ target_xfer_memory_error (TARGET_XFER_E_IO, memaddr + xfered);
+ if (xfer < 0)
+ target_xfer_memory_error (xfer, memaddr + xfered);
+ xfered += xfer;
+ QUIT;
+ }
}
/* Same as target_read_stack, but report an error if can't read. */
const gdb_byte *writebuf,
ULONGEST offset, LONGEST len);
-static LONGEST target_xfer_partial (struct target_ops *ops,
- enum target_object object,
- const char *annex,
- void *readbuf, const void *writebuf,
- ULONGEST offset, LONGEST len);
-
static struct gdbarch *default_thread_architecture (struct target_ops *ops,
ptid_t ptid);
return addr;
}
+const char *
+target_xfer_error_to_string (enum target_xfer_error err)
+{
+#define CASE(X) case X: return #X
+ switch (err)
+ {
+ CASE(TARGET_XFER_E_IO);
+ CASE(TARGET_XFER_E_UNAVAILABLE);
+ default:
+ return "<unknown>";
+ }
+#undef CASE
+};
+
+
#undef MIN
#define MIN(A, B) (((A) <= (B)) ? (A) : (B))
/* No use trying further, we know some memory starting
at MEMADDR isn't available. */
- return -1;
+ return TARGET_XFER_E_UNAVAILABLE;
}
/* Don't try to read more than how much is available, in
/* For docs see target.h, to_xfer_partial. */
-static LONGEST
+LONGEST
target_xfer_partial (struct target_ops *ops,
enum target_object object, const char *annex,
void *readbuf, const void *writebuf,
/* Possible future objects: TARGET_OBJECT_FILE, ... */
};
+/* Possible error codes returned by target_xfer_partial, etc. */
+
+enum target_xfer_error
+{
+ /* Generic I/O error. Note that it's important that this is '-1',
+ as we still have target_xfer-related code returning hardcoded
+ '-1' on error. */
+ TARGET_XFER_E_IO = -1,
+
+ /* Transfer failed because the piece of the object requested is
+ unavailable. */
+ TARGET_XFER_E_UNAVAILABLE = -2,
+
+ /* Keep list in sync with target_xfer_error_to_string. */
+};
+
+/* Return the string form of ERR. */
+
+extern const char *target_xfer_error_to_string (enum target_xfer_error err);
+
/* Enumeration of the kinds of traceframe searches that a target may
be able to perform. */
enum target_object object,
const char *annex);
+/* See target_ops->to_xfer_partial. */
+
+extern LONGEST target_xfer_partial (struct target_ops *ops,
+ enum target_object object,
+ const char *annex,
+ void *readbuf, const void *writebuf,
+ ULONGEST offset, LONGEST len);
+
/* Wrappers to target read/write that perform memory transfers. They
throw an error if the memory transfer fails.
data-specific information to the target.
Return the number of bytes actually transfered, zero when no
- further transfer is possible, and -1 when the transfer is not
+ further transfer is possible, and a negative error code (really
+ an 'enum target_xfer_error' value) when the transfer is not
supported. Return of a positive value smaller than LEN does
not indicate the end of the object, only the end of the
transfer; higher level code should continue transferring if
projects / external / binutils.git / commitdiff