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.
This commit is contained in:
Pedro Alves
parent
65fd058fe6
commit
6be7b56e00
@ -1,3 +1,19 @@
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2013-08-22 Pedro Alves <palves@redhat.com>
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PR gdb/15871
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* corefile.c (target_xfer_memory_error): New function.
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(memory_error): Defer EIO to target_memory_error.
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(read_memory): Use target_xfer_partial, and handle finer-grained
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target xfer errors.
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* target.c (target_xfer_error_to_string): New function.
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(memory_xfer_partial_1): If memory is known to be
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unavailable, return TARGET_XFER_E_UNAVAILABLE instead of -1.
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(target_xfer_partial): Make extern.
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* target.h (enum target_xfer_error): New enum.
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(target_xfer_error_to_string): Declare function.
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(target_xfer_partial): Declare function.
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(struct target_ops) <xfer_partial>: Adjust describing comment.
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2013-08-22 Alan Modra <amodra@gmail.com>
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* configure.host: Support powerpc64le-linux and powerpcle-linux hosts.
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@ -193,17 +193,39 @@ Use the \"file\" or \"exec-file\" command."));
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}
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/* Report a target xfer memory error by throwing a suitable
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exception. */
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static void
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target_xfer_memory_error (enum target_xfer_error err, CORE_ADDR memaddr)
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{
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switch (err)
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{
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case TARGET_XFER_E_IO:
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/* Actually, address between memaddr and memaddr + len was out of
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bounds. */
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throw_error (MEMORY_ERROR,
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_("Cannot access memory at address %s"),
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paddress (target_gdbarch (), memaddr));
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case TARGET_XFER_E_UNAVAILABLE:
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throw_error (NOT_AVAILABLE_ERROR,
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_("Memory at address %s unavailable."),
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paddress (target_gdbarch (), memaddr));
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default:
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internal_error (__FILE__, __LINE__,
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"unhandled target_xfer_error: %s (%s)",
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target_xfer_error_to_string (err),
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plongest (err));
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}
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}
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/* Report a memory error by throwing a MEMORY_ERROR error. */
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void
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memory_error (int status, CORE_ADDR memaddr)
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{
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if (status == EIO)
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/* Actually, address between memaddr and memaddr + len was out of
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bounds. */
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throw_error (MEMORY_ERROR,
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_("Cannot access memory at address %s"),
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paddress (target_gdbarch (), memaddr));
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target_xfer_memory_error (TARGET_XFER_E_IO, memaddr);
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else
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throw_error (MEMORY_ERROR,
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_("Error accessing memory address %s: %s."),
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@ -216,11 +238,22 @@ memory_error (int status, CORE_ADDR memaddr)
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void
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read_memory (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
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{
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int status;
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LONGEST xfered = 0;
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status = target_read_memory (memaddr, myaddr, len);
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if (status != 0)
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memory_error (status, memaddr);
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while (xfered < len)
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{
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LONGEST xfer = target_xfer_partial (current_target.beneath,
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TARGET_OBJECT_MEMORY, NULL,
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myaddr + xfered, NULL,
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memaddr + xfered, len - xfered);
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if (xfer == 0)
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target_xfer_memory_error (TARGET_XFER_E_IO, memaddr + xfered);
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if (xfer < 0)
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target_xfer_memory_error (xfer, memaddr + xfered);
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xfered += xfer;
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QUIT;
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}
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}
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/* Same as target_read_stack, but report an error if can't read. */
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25
gdb/target.c
25
gdb/target.c
@ -81,12 +81,6 @@ static LONGEST current_xfer_partial (struct target_ops *ops,
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const gdb_byte *writebuf,
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ULONGEST offset, LONGEST len);
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static LONGEST target_xfer_partial (struct target_ops *ops,
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enum target_object object,
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const char *annex,
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void *readbuf, const void *writebuf,
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ULONGEST offset, LONGEST len);
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static struct gdbarch *default_thread_architecture (struct target_ops *ops,
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ptid_t ptid);
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@ -1238,6 +1232,21 @@ target_translate_tls_address (struct objfile *objfile, CORE_ADDR offset)
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return addr;
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}
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const char *
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target_xfer_error_to_string (enum target_xfer_error err)
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{
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#define CASE(X) case X: return #X
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switch (err)
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{
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CASE(TARGET_XFER_E_IO);
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CASE(TARGET_XFER_E_UNAVAILABLE);
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default:
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return "<unknown>";
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}
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#undef CASE
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};
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#undef MIN
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#define MIN(A, B) (((A) <= (B)) ? (A) : (B))
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@ -1523,7 +1532,7 @@ memory_xfer_partial_1 (struct target_ops *ops, enum target_object object,
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/* No use trying further, we know some memory starting
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at MEMADDR isn't available. */
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return -1;
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return TARGET_XFER_E_UNAVAILABLE;
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}
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/* Don't try to read more than how much is available, in
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@ -1700,7 +1709,7 @@ make_show_memory_breakpoints_cleanup (int show)
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/* For docs see target.h, to_xfer_partial. */
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static LONGEST
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LONGEST
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target_xfer_partial (struct target_ops *ops,
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enum target_object object, const char *annex,
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void *readbuf, const void *writebuf,
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31
gdb/target.h
31
gdb/target.h
@ -199,6 +199,26 @@ enum target_object
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/* Possible future objects: TARGET_OBJECT_FILE, ... */
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};
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/* Possible error codes returned by target_xfer_partial, etc. */
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enum target_xfer_error
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{
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/* Generic I/O error. Note that it's important that this is '-1',
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as we still have target_xfer-related code returning hardcoded
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'-1' on error. */
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TARGET_XFER_E_IO = -1,
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/* Transfer failed because the piece of the object requested is
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unavailable. */
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TARGET_XFER_E_UNAVAILABLE = -2,
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/* Keep list in sync with target_xfer_error_to_string. */
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};
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/* Return the string form of ERR. */
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extern const char *target_xfer_error_to_string (enum target_xfer_error err);
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/* Enumeration of the kinds of traceframe searches that a target may
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be able to perform. */
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@ -293,6 +313,14 @@ extern char *target_read_stralloc (struct target_ops *ops,
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enum target_object object,
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const char *annex);
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/* See target_ops->to_xfer_partial. */
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extern LONGEST target_xfer_partial (struct target_ops *ops,
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enum target_object object,
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const char *annex,
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void *readbuf, const void *writebuf,
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ULONGEST offset, LONGEST len);
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/* Wrappers to target read/write that perform memory transfers. They
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throw an error if the memory transfer fails.
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@ -475,7 +503,8 @@ struct target_ops
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data-specific information to the target.
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Return the number of bytes actually transfered, zero when no
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further transfer is possible, and -1 when the transfer is not
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further transfer is possible, and a negative error code (really
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an 'enum target_xfer_error' value) when the transfer is not
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supported. Return of a positive value smaller than LEN does
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not indicate the end of the object, only the end of the
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transfer; higher level code should continue transferring if
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