PR gdb/28947
The address_significant gdbarch setting was introduced as a way to remove
non-address bits from pointers, and it is specified by a constant. This
constant represents the number of address bits in a pointer.
Right now AArch64 is the only architecture that uses it, and 56 was a
correct option so far.
But if we are using Pointer Authentication (PAuth), we might use up to 2 bytes
from the address space to store the required information. We could also have
cases where we're using both PAuth and MTE.
We could adjust the constant to 48 to cover those cases, but this doesn't
cover the case where GDB needs to sign-extend kernel addresses after removal
of the non-address bits.
This has worked so far because bit 55 is used to select between kernel-space
and user-space addresses. But trying to clear a range of bits crossing the
bit 55 boundary requires the hook to be smarter.
The following patch renames the gdbarch hook from significant_addr_bit to
remove_non_address_bits and passes a pointer as opposed to the number of
bits. The hook is now responsible for removing the required non-address bits
and sign-extending the address if needed.
While at it, make GDB and GDBServer share some more code for aarch64 and add a
new arch-specific testcase gdb.arch/aarch64-non-address-bits.exp.
Bug-url: https://sourceware.org/bugzilla/show_bug.cgi?id=28947
Approved-By: Simon Marchi <simon.marchi@efficios.com>
Currently, on x86_64, a little endian target, I get:
...
$ gdb -q -batch -ex "maint print architecture" | grep " = floatformat"
gdbarch_dump: bfloat16_format = floatformat_bfloat16_big
gdbarch_dump: double_format = floatformat_ieee_double_big
gdbarch_dump: float_format = floatformat_ieee_single_big
gdbarch_dump: half_format = floatformat_ieee_half_big
gdbarch_dump: long_double_format = floatformat_i387_ext
...
which suggests big endian.
This is due to this bit of code in pformat:
...
/* Just print out one of them - this is only for diagnostics. */
return format[0]->name;
...
Fix this by using gdbarch_byte_order to pick the appropriate index, such that
we have the more accurate:
...
gdbarch_dump: bfloat16_format = floatformat_bfloat16_little
gdbarch_dump: half_format = floatformat_ieee_half_little
gdbarch_dump: float_format = floatformat_ieee_single_little
gdbarch_dump: double_format = floatformat_ieee_double_little
gdbarch_dump: long_double_format = floatformat_i387_ext
...
Tested on x86_64-linux.
Currently, a non-trivial return value from a function cannot currently be
reliably determined on PowerPC. This is due to the fact that the PowerPC
ABI uses register r3 to store the address of the buffer containing the
non-trivial return value when the function is called. The PowerPC ABI
does not guarantee the value in register r3 is not modified in the
function. Thus the value in r3 cannot be reliably used to obtain the
return addreses on exit from the function.
This patch adds a new gdbarch method to allow PowerPC to access the value
of r3 on entry to a function. On PowerPC, the new gdbarch method attempts
to use the DW_OP_entry_value for the DWARF entries, when exiting the
function, to determine the value of r3 on entry to the function. This
requires the use of the -fvar-tracking compiler option to compile the
user application thus generating the DW_OP_entry_value in the binary. The
DW_OP_entry_value entries in the binary file allows GDB to resolve the
DW_TAG_call_site entries. This new gdbarch method is used to get the
return buffer address, in the case of a function returning a nontrivial
data type, on exit from the function. The GDB function should_stop checks
to see if RETURN_BUF is non-zero. By default, RETURN_BUF will be set to
zero by the new gdbarch method call for all architectures except PowerPC.
The get_return_value function will be used to obtain the return value on
all other architectures as is currently being done if RETURN_BUF is zero.
On PowerPC, the new gdbarch method will return a nonzero address in
RETURN_BUF if the value can be determined. The value_at function uses the
return buffer address to get the return value.
This patch fixes five testcase failures in gdb.cp/non-trivial-retval.exp.
The correct function return values are now reported.
Note this patch is dependent on patch: "PowerPC, function
ppc64_sysv_abi_return_value add missing return value convention".
This patch has been tested on Power 10 and x86-64 with no regressions.
This changes gdbarch to use the "predefault" to initialize its members
inline. This required changing a couple of the Value instantiations
to avoid a use of "gdbarch" during initialization, but on the whole I
think this is better -- it removes a hidden ordering dependency.
If you run gdbarch.py today, you'll get local modifications compared
to what's in the tree, like:
--- c/gdb/gdbarch-gen.h
+++ w/gdb/gdbarch-gen.h
@@ -315,8 +315,8 @@ extern void set_gdbarch_register_type (struct gdbarch *gdbarch, gdbarch_register
should match the address at which the breakpoint was set in the dummy
frame. */
-typedef struct frame_id (gdbarch_dummy_id_ftype) (struct gdbarch *gdbarch, frame_info_ptr this_frame);
-extern struct frame_id gdbarch_dummy_id (struct gdbarch *gdbarch, frame_info_ptr this_frame);
+typedef struct frame_id (gdbarch_dummy_id_ftype) (struct gdbarch *gdbarch, frame_info_ptr this_frame);
+extern struct frame_id gdbarch_dummy_id (struct gdbarch *gdbarch, frame_info_ptr this_frame);
extern void set_gdbarch_dummy_id (struct gdbarch *gdbarch, gdbarch_dummy_id_ftype *dummy_id);
etc.
The extra space comes from the "frame_info_ptr " param that appears in
a number of gdbarch methods in gdbarch-components.py. With the extra
space removed, running ./gdbarch.py generates the exact code that's in
the tree already.
Change-Id: If7d20b8c6b2fd9ff466142a01bd2611c9ef9f53e
This changes GDB to use frame_info_ptr instead of frame_info *
The substitution was done with multiple sequential `sed` commands:
sed 's/^struct frame_info;/class frame_info_ptr;/'
sed 's/struct frame_info \*/frame_info_ptr /g' - which left some
issues in a few files, that were manually fixed.
sed 's/\<frame_info \*/frame_info_ptr /g'
sed 's/frame_info_ptr $/frame_info_ptr/g' - used to remove whitespace
problems.
The changed files were then manually checked and some 'sed' changes
undone, some constructors and some gets were added, according to what
made sense, and what Tromey originally did
Co-Authored-By: Bruno Larsen <blarsen@redhat.com>
Approved-by: Tom Tomey <tom@tromey.com>
This commit adds asserts to gdbarch_register_name that validate the
parameters, and the return value.
The interesting thing here is that gdbarch_register_name is generated
by gdbarch.py, and so, to add these asserts, I need to update the
generation script.
I've added two new arguments for Functions and Methods (as declared in
gdbarch-components.py), these arguments are 'param_checks' and
'result_checks'. Each of these new arguments can be used to list some
expressions that are then used within gdb_assert calls in the
generated code.
The asserts that validate the API as described in the comment I added
to gdbarch_register_name a few commits back; the register number
passed in needs to be a valid cooked register number, and the result
being returned should not be nullptr.
After the previous commit, this commit sets out to formalise the API
for gdbarch_register_name. Not every architecture is actually in
compliance with the API I set out here, but I believe that most are.
I think architectures that don't comply with the API laid out here
will fail the gdb.base/completion.exp test.
The claims in the comment are I feel, best demonstrated with the
asserts in this code:
const char *
gdbarch_register_name (struct gdbarch *gdbarch, int regnr)
{
gdb_assert (regnr >= 0);
gdb_assert (regnr < gdbarch_num_cooked_regs (gdbarch));
const char *name = gdbarch->register_name (gdbarch, regnr);
gdb_assert (name != nullptr);
return name;
}
Like I said, I don't believe every architecture follows these rules
right now, which is why I'm not actually adding any asserts. Instead,
this commit adds a comment to gdbarch_register_name, this comment is
where I'd like to get to, rather than where we are right now.
Subsequent commits will fix all targets to be in compliance with this
comment, and will even add the asserts shown above to
gdbarch_register_name.
Constify the input parameters of the various auxv parse functions, they
don't need to modify the raw auxv data.
Change-Id: I13eacd5ab8e925ec2b5c1f7722cbab39c41516ec
This changs solib_ops to be an ordinary gdbarch value and updates all
the uses. This removes a longstanding FIXME and makes the code
somewhat cleaner as well.
Teach GDB how to dump memory tags for AArch64 when using the gcore command
and how to read memory tag data back from a core file generated by GDB
(via gcore) or by the Linux kernel.
The format is documented in the Linux Kernel documentation [1].
Each tagged memory range (listed in /proc/<pid>/smaps) gets dumped to its
own PT_AARCH64_MEMTAG_MTE segment. A section named ".memtag" is created for each
of those segments when reading the core file back.
To save a little bit of space, given MTE tags only take 4 bits, the memory tags
are stored packed as 2 tags per byte.
When reading the data back, the tags are unpacked.
I've added a new testcase to exercise the feature.
Build-tested with --enable-targets=all and regression tested on aarch64-linux
Ubuntu 20.04.
[1] Documentation/arm64/memory-tagging-extension.rst (Core Dump Support)
A rather straightforward patch to change an instance of callback +
void pointer to gdb::function_view, allowing pasing lambdas that
capture, and eliminating the need for the untyped pointer.
Change-Id: I73ed644e7849945265a2c763f79f5456695b0037
Change gdbarch_register_reggroup_p to take a 'const struct reggroup *'
argument. This requires a change to the gdb/gdbarch-components.py
script, regeneration of gdbarch.{c,h}, and then updates to all the
architectures that implement this method.
There should be no user visible changes after this commit.
After the previous commit, which removes the predicate function
gdbarch_register_type_p, I noticed that the gdbarch->register_type
field was not checked at in the verify_gdbarch function.
More than not being checked, the field wasn't mentioned at all.
I find this strange, I would expect that every field would at least be
mentioned - we already generate comments for some fields saying that
this field is _not_ being checked, so the fact that this field isn't
being checked looks (to me), like this field is somehow slipping
through the cracks.
The comment at the top of gdbarch-components.py tries to explain how
the validation is done. I didn't understand this comment completely,
but, I think this final sentence:
"Otherwise, the check is done against 0 (really NULL for function
pointers, but same idea)."
Means that, if non of the other cases apply, then the field should be
checked against 0, with 0 indicating that the field is invalid (was
not set by the tdep code). However, this is clearly not being done.
Looking in gdbarch.py at the code to generate verify_gdbarch we do
find that there is a case that is not handled, the case where the
'invalid' field is set true True, but non of the other cases apply.
In this commit I propose two changes:
1. Handle the case where the 'invalid' field of a property is set to
True, this should perform a check for the field of gdbarch still
being set to 0, and
2. If the if/else series that generates verify_gdbarch doesn't handle
a property then we should raise an exception. This means that if a
property is added which isn't handled, we should no longer silently
ignore it.
After doing this, I re-generated the gdbarch files and saw that the
following gdbarch fields now had new validation checks:
register_type
believe_pcc_promotion
register_to_value
value_to_register
frame_red_zone_size
displaced_step_restore_all_in_ptid
solib_symbols_extension
Looking at how these are currently set in the various -tdep.c files, I
believe the only one of these that is required to be set for all
architectures is the register_type field.
And so, for all of the other fields, I've changed the property
definition on gdbarch-components.py, setting the 'invalid' field to
False.
Now, after re-generation, the register_type field is checked against
0, thus an architecture that doesn't set_gdbarch_register_type will
now fail during validation. For all the other fields we skip the
validation, in which case, it is find for an architecture to not set
this field.
My expectation is that there should be no user visible changes after
this commit. Certainly for all fields except register_type, all I've
really done is cause some extra comments to be generated, so I think
that's clearly fine.
For the register_type field, my claim is that any architecture that
didn't provide this would fail when creating its register cache, and I
couldn't spot an architecture that doesn't provide this hook. As
such, I think this change should be fine too.
I don't believe that the gdbarch_register_type_p predicate is called
anywhere in GDB, and the gdbarch_register_type function is called
without checking the gdbarch_register_type_p predicate function
everywhere it is used, for example in
init_regcache_descr (regcache.c).
My claim is that the gdbarch_register_type function is required for
every architecture, and GDB will not work if this function is not
supplied.
And so, in this commit, I remove the 'predicate=True' from
gdbarch-components.py for the 'register_type' field, and regenerate
the gdbarch files.
There should be no user visible changes after this commit.
This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.
For the avoidance of doubt, all changes in this commits were
performed by the script.
During review, it was suggested to change the "params" parameter from a
tuple to a list, for esthetic reasons. The empty ones are still tuples
though, they should probably be changed to be empty lists, for
consistency. It does not change anything in the script result.
Change-Id: If13c6c527aa167a5ee5b45740e5f1bda1e9517e4
The new gdbarch.sh approach will be to edit a Python file, rather than
adding a line to a certain part of gdbarch.sh. We use the existing sh
code, though, to generate the first draft of this .py file.
Documentation on the format will come in a subsequent patch.
Note that some info (like "staticdefault") in the current code is
actually unused, and so is ignored by this new generator.
