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authorPedro Alves <palves@redhat.com>2013-08-22 10:00:05 +0000
committerPedro Alves <palves@redhat.com>2013-08-22 10:00:05 +0000
commit6be7b56e0072f516ed2ffceab196018025bc32a9 (patch)
tree12f16f2caf88d28cab56d371443af10e0d987256
parent65fd058fe6c707e083dd61446b93e206275bf3bb (diff)
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PR gdb/15871: Unavailable entry value is not shown correctly
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.
-rw-r--r--gdb/ChangeLog16
-rw-r--r--gdb/corefile.c51
-rw-r--r--gdb/target.c25
-rw-r--r--gdb/target.h31
4 files changed, 105 insertions, 18 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 8caad2f..55e2337 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,19 @@
+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.
diff --git a/gdb/corefile.c b/gdb/corefile.c
index a86f4b3..cb7f14e 100644
--- a/gdb/corefile.c
+++ b/gdb/corefile.c
@@ -193,17 +193,39 @@ Use the \"file\" or \"exec-file\" command."));
}
+/* 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."),
@@ -216,11 +238,22 @@ memory_error (int status, CORE_ADDR memaddr)
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. */
diff --git a/gdb/target.c b/gdb/target.c
index 377724d..f18661b 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -81,12 +81,6 @@ static LONGEST current_xfer_partial (struct target_ops *ops,
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);
@@ -1238,6 +1232,21 @@ target_translate_tls_address (struct objfile *objfile, CORE_ADDR offset)
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))
@@ -1523,7 +1532,7 @@ memory_xfer_partial_1 (struct target_ops *ops, enum target_object object,
/* 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
@@ -1700,7 +1709,7 @@ make_show_memory_breakpoints_cleanup (int show)
/* 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,
diff --git a/gdb/target.h b/gdb/target.h
index d538e02..6959503 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -199,6 +199,26 @@ enum target_object
/* 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. */
@@ -293,6 +313,14 @@ extern char *target_read_stralloc (struct target_ops *ops,
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.
@@ -475,7 +503,8 @@ struct target_ops
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