On PPC64, with the test case included in an earlier patch, we found
that "finish" would still not correctly find the return value via
entry values.
The issue is simple. The compiler emits:
0x00000000100032b8 <+28>: bl 0x1000320c <pck__create_large>
0x00000000100032bc <+32>: nop
0x00000000100032c0 <+36>: li r9,42
... but the DWARF says:
<162a> DW_AT_call_return_pc: 0x100032c0
That is, the declared return PC is one instruction past the actual
return PC.
This patch adds a new arch hook to handle this scenario, and
implements it for PPC64. Some care is taken so that GDB will continue
to work if this compiler bug is fixed. A GCC patch is here:
https://gcc.gnu.org/pipermail/gcc-patches/2023-March/613336.html
No check for 'nop' is done, as subsequent discussion revealed that the
linker might replace this with another instruction.
PowerPC supports two 128-bit floating point formats, the IBM long double
and IEEE 128-bit float. The issue is the DWARF information does not
distinguish between the two. There have been proposals of how to extend
the DWARF information as discussed in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104194
but has not been fully implemented.
GCC introduced the _Float128 internal type as a work around for the issue.
The workaround is not transparent to GDB. The internal _Float128 type
name is printed rather then the user specified long double type. This
patch adds a new gdbarch method to allow PowerPC to detect the GCC
workaround. The workaround checks for "_Float128" name when reading the
base typedef from the die_info. If the workaround is detected, the type
and format fields from the _Float128 typedef are copied to the long
double typedef. The same is done for the complex long double typedef.
This patch fixes 74 regression test failures in
gdb.base/whatis-ptype-typedefs.exp on PowerPC with IEEE float 128 as the
default on GCC. It fixes one regression test failure in
gdb.base/complex-parts.exp.
The patch has been tested on Power 10 where GCC defaults to IEEE Float
128-bit and on Power 10 where GCC defaults to the IBM 128-bit float. The
patch as also been tested on X86-64 with no new regression failures.
This commit aims to address a problem that exists with the current
approach to displaced stepping, and was identified in PR gdb/22921.
Displaced stepping is currently supported on AArch64, ARM, amd64,
i386, rs6000 (ppc), and s390. Of these, I believe there is a problem
with the current approach which will impact amd64 and ARM, and can
lead to random register corruption when the inferior makes use of
asynchronous signals and GDB is using displaced stepping.
The problem can be found in displaced_step_buffers::finish in
displaced-stepping.c, and is this; after GDB tries to perform a
displaced step, and the inferior stops, GDB classifies the stop into
one of two states, either the displaced step succeeded, or the
displaced step failed.
If the displaced step succeeded then gdbarch_displaced_step_fixup is
called, which has the job of fixing up the state of the current
inferior as if the step had not been performed in a displaced manner.
This all seems just fine.
However, if the displaced step is considered to have not completed
then GDB doesn't call gdbarch_displaced_step_fixup, instead GDB
remains in displaced_step_buffers::finish and just performs a minimal
fixup which involves adjusting the program counter back to its
original value.
The problem here is that for amd64 and ARM setting up for a displaced
step can involve changing the values in some temporary registers. If
the displaced step succeeds then this is fine; after the step the
temporary registers are restored to their original values in the
architecture specific code.
But if the displaced step does not succeed then the temporary
registers are never restored, and they retain their modified values.
In this context a temporary register is simply any register that is
not otherwise used by the instruction being stepped that the
architecture specific code considers safe to borrow for the lifetime
of the instruction being stepped.
In the bug PR gdb/22921, the amd64 instruction being stepped is
an rip-relative instruction like this:
jmp *0x2fe2(%rip)
When we displaced step this instruction we borrow a register, and
modify the instruction to something like:
jmp *0x2fe2(%rcx)
with %rcx having its value adjusted to contain the original %rip
value.
Now if the displaced step does not succeed, then %rcx will be left
with a corrupted value. Obviously corrupting any register is bad; in
the bug report this problem was spotted because %rcx is used as a
function argument register.
And finally, why might a displaced step not succeed? Asynchronous
signals provides one reason. GDB sets up for the displaced step and,
at that precise moment, the OS delivers a signal (SIGALRM in the bug
report), the signal stops the inferior at the address of the displaced
instruction. GDB cancels the displaced instruction, handles the
signal, and then tries again with the displaced step. But it is that
first cancellation of the displaced step that causes the problem; in
that case GDB (correctly) sees the displaced step as having not
completed, and so does not perform the architecture specific fixup,
leaving the register corrupted.
The reason why I think AArch64, rs600, i386, and s390 are not effected
by this problem is that I don't believe these architectures make use
of any temporary registers, so when a displaced step is not completed
successfully, the minimal fix up is sufficient.
On amd64 we use at most one temporary register.
On ARM, looking at arm_displaced_step_copy_insn_closure, we could
modify up to 16 temporary registers, and the instruction being
displaced stepped could be expanded to multiple replacement
instructions, which increases the chances of this bug triggering.
This commit only aims to address the issue on amd64 for now, though I
believe that the approach I'm proposing here might be applicable for
ARM too.
What I propose is that we always call gdbarch_displaced_step_fixup.
We will now pass an extra argument to gdbarch_displaced_step_fixup,
this a boolean that indicates whether GDB thinks the displaced step
completed successfully or not.
When this flag is false this indicates that the displaced step halted
for some "other" reason. On ARM GDB can potentially read the
inferior's program counter in order figure out how far through the
sequence of replacement instructions we got, and from that GDB can
figure out what fixup needs to be performed.
On targets like amd64 the problem is slightly easier as displaced
stepping only uses a single replacement instruction. If the displaced
step didn't complete the GDB knows that the single instruction didn't
execute.
The point is that by always calling gdbarch_displaced_step_fixup, each
architecture can now ensure that the inferior state is fixed up
correctly in all cases, not just the success case.
On amd64 this ensures that we always restore the temporary register
value, and so bug PR gdb/22921 is resolved.
In order to move all architectures to this new API, I have moved the
minimal roll-back version of the code inside the architecture specific
fixup functions for AArch64, rs600, s390, and ARM. For all of these
except ARM I think this is good enough, as no temporaries are used all
that's needed is the program counter restore anyway.
For ARM the minimal code is no worse than what we had before, though I
do consider this architecture's displaced-stepping broken.
I've updated the gdb.arch/amd64-disp-step.exp test to cover the
'jmpq*' instruction that was causing problems in the original bug, and
also added support for testing the displaced step in the presence of
asynchronous signal delivery.
I've also added two new tests (for amd64 and i386) that check that GDB
can correctly handle displaced stepping over a single instruction that
branches to itself. I added these tests after a first version of this
patch relied too much on checking the program-counter value in order
to see if the displaced instruction had executed. This works fine in
almost all cases, but when an instruction branches to itself a pure
program counter check is not sufficient. The new tests expose this
problem.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=22921
Approved-By: Pedro Alves <pedro@palves.net>
This commit tweaks displaced_step_finish & friends to pass down a
target_waitstatus instead of a gdb_signal. This is needed because a
patch later in the step-over-{thread-exit,clone] series will want to
make displaced_step_buffers::finish handle
TARGET_WAITKIND_THREAD_EXITED. It also helps with the
TARGET_WAITKIND_THREAD_CLONED patch later in that same series.
It's also a bit more logical this way, as we don't have to pass down
signals when the thread didn't actually stop for a signal. So we can
also think of it as a clean up.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27338
Change-Id: I4c5d338647b028071bc498c4e47063795a2db4c0
Approved-By: Andrew Burgess <aburgess@redhat.com>
The comment on the gdbarch_displaced_step_fixup gdbarch method
indicates that this method is optional and that GDB will perform some
default if this method is not supplied. As such we define a predicate
gdbarch_displaced_step_fixup_p.
It may have been true at one point that the fixup method was optional,
but it is no longer true. If this method is not defined and GDB tries
to complete a displaced step, then GDB is going to crash.
Additionally the gdbarch_displaced_step_fixup_p predicate is not used
anywhere in GDB.
In this commit I have removed the gdbarch_displaced_step_fixup_p
predicate, and I have updated the validation check for the
gdbarch_displaced_step_fixup method; if the
gdbarch_displaced_step_copy_insn method is defined then the fixup
method must also be defined.
I believe I've manually checked all the current places where
gdbarch_displaced_step_copy_insn is defined and they all also define
the fixup method, so this change should cause no problems for anyone.
There should be no user visible changes after this commit.
Approved-By: Pedro Alves <pedro@palves.net>
The gdbarch::max_insn_length field is used mostly to support displaced
stepping; it controls the size of the buffers allocated for the
displaced-step instruction, and is also used when first copying the
instruction, and later, when fixing up the instruction, in order to
read in and parse the instruction being stepped.
However, it has started to be used in other places in GDB, for
example, it's used in the Python disassembler API, and it is used on
amd64 as part of branch-tracing instruction classification.
The problem is that the value assigned to max_insn_length is not
always the maximum instruction length, but sometimes is a multiple of
that length, as required to support displaced stepping, see rs600,
ARM, and AArch64 for examples of this.
It seems to me that we are overloading the meaning of the
max_insn_length field, and I think that could potentially lead to
confusion.
I propose that we add a new gdbarch field,
gdbarch::displaced_step_buffer_length, this new field will do
exactly what it says on the tin; represent the required displaced step
buffer size. The max_insn_length field can then do exactly what it
claims to do; represent the maximum length of a single instruction.
As some architectures (e.g. i386, and amd64) only require their
displaced step buffers to be a single instruction in size, I propose
that the default for displaced_step_buffer_length will be the
value of max_insn_length. Architectures than need more buffer space
can then override this default as needed.
I've updated all architectures to setup the new field if appropriate,
and I've audited all calls to gdbarch_max_insn_length and switched to
gdbarch_displaced_step_buffer_length where appropriate.
There should be no user visible changes after this commit.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
I noticed that there are a bunch of 'predefault="0"' lines in
gdbarch_components.py, and that some (just some, not all) of these are
not needed.
The gdbarch is already zero initialized, but these lines seem to
exists so that we can know when to compare against "0" and when to
compare against "NULL". At least, this seems to be useful in some
places in the generated code.
Specifically, if we remove the predefault="0" line from the
max_insn_length component then we end up generating a line like:
gdb_assert (gdbarch->max_insn_length != NULL);
which doesn't compile as we compare a ULONGEST to NULL.
In this commit I remove all the predefault="0" lines that I claim are
obviously not needed. These are lines for components that are not
Values (i.e. the component holds a function pointer anyway), or for
Value components that hold a pointer type, in which case using NULL is
fine.
The only changes after this commit are some fields that have nullptr
as their initial value, and gcore_bfd_target now compares to NULL not
0 in gdbarch_gcore_bfd_target_p, which, given the field is of type
'const char *', seems like an improvement.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
We currently generate some validation code within the gdbarch getter
methods.
This commit adjusts the algorithm used to generate this validation
slightly to make the gdbarch.py code (I think) clearer; there's no
significant changes to what is generated.
The validation algorithm for gdbarch values is now:
- If the Value has an 'invalid' field that is a string, use that for
validation,
- If the Value has its 'predicate' field set to true, then check the
predicate returns true, this ensures the predicate has been
called,
- If the Value has its 'invalid' field set to True, or the Value has
'postdefault' field, then check the fields has changed from its
initial value,
- Otherwise no validation is performed.
The only changes after this commit are:
- Some comments change slightly, and
- For 'gcore_bfd_target' and 'max_insn_length' we now validate by
calling the predicate rather than checking the field value
directly, the underlying check being performed is unchanged
though.
There should be no user visible changes after this commit.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
For some reason the following value components of gdbarch:
bfloat16_format
half_format
float_format
double_format
long_double_format
so_ops
All use a postdefault but no predefault to set the default value for
the component.
As the postdefault values for these components are all constant
pointers that don't depend on other fields within the gdbarch, then I
don't see any reason why we couldn't use a predefault instead.
So lets do that.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This commit ensures that the 'invalid' property of all components is
either True, False, or a string.
Additionally, this commit allows a component to have both a predicate
and for the 'invalid' property to be a string.
Removing the option for 'invalid' to be None allows us to simplify the
algorithms in gdbarch.py a little.
Allowing a component to have both a predicate and an 'invalid' string
means that we can validate the value that a tdep sets into a field,
but also allow a predicate to ensure that the field has changed from
the default.
This functionality isn't going to be used in this series, but I have
tested it locally and believe that it would work, and this might make
it easier for others to add new components in the future.
In gdbarch_types.py, I've updated the type annotations to show that
the 'invalid' field should not be None, and I've changed the default
for this field from None to False.
The change to using False as the default is temporary. Later in this
series I'm going to change the default to True, but we need more fixes
before that can be done.
Additionally, in gdbarch_types.py I've removed an assert from
Component.get_predicate. This assert ensured that we didn't have the
predicate field set to True and the invalid field set to a string.
However, no component currently uses this configuration, and after
this commit, that combination is now supported, so the assert can be
removed.
As a consequence of the gdbarch_types.py changes we see some
additional comments generated in gdbarch.c about verification being
skipped due to the invalid field being False. This comment is inline
with plenty of other getters that also have a similar comment. Plenty
of the getters do have validation, so I think it is reasonable to have
a comment noting that the validation has been skipped for a specific
reason, rather than due to some bug.
In gdbarch_components.py I've had to add 'invalid=True' for two
components: gcore_bfd_target and max_insn_length, without this the
validation in the gdbarch getter would disappear.
And in gdbarch.py I've reworked the logic for generating the
verify_gdbarch function, and for generating the getter functions.
The logic for generating the getter functions is still not ideal, I
ended up having to add this additional logic block:
elif c.postdefault is not None and c.predefault is not None:
print(" /* Check variable changed from pre-default. */", file=f)
print(f" gdb_assert (gdbarch->{c.name} != {c.predefault});", file=f)
which was needed to ensure we continued to generate the same code as
before, without this the fact that invalid is now False when it would
previously have been None, meant that we dropped the gdb_assert in
favour of a comment like:
print(f" /* Skip verify of {c.name}, invalid_p == 0 */", file=f)
which is clearly not a good change. We could potentially look at
improving this in a later commit, but I don't plan to do that in this
series.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
When I converted gdbarch to use the registry, I forgot to remove the
two fields that were used to implement the previous approach. This
patch removes them. Tested by rebuilding.
It's currently not clear how the ownership of gdbarch_tdep objects
works. In fact, nothing ever takes ownership of it. This is mostly
fine because we never free gdbarch objects, and thus we never free
gdbarch_tdep objects. There is an exception to that however: when
initialization fails, we do free the gdbarch object that is not going to
be used, and we free the tdep too. Currently, i386 and s390 do it.
To make things clearer, change gdbarch_alloc so that it takes ownership
of the tdep. The tdep is thus automatically freed if the gdbarch is
freed.
Change all gdbarch initialization functions to pass a new gdbarch_tdep
object to gdbarch_alloc and then retrieve a non-owning reference from
the gdbarch object.
Before this patch, the xtensa architecture had a single global instance
of xtensa_gdbarch_tdep. Since we need to pass a dynamically allocated
gdbarch_tdep_base instance to gdbarch_alloc, remove this global
instance, and dynamically allocate one as needed, like we do for all
other architectures. Make the `rmap` array externally visible and
rename it to the less collision-prone `xtensa_rmap` name.
Change-Id: Id3d70493ef80ce4bdff701c57636f4c79ed8aea2
Approved-By: Andrew Burgess <aburgess@redhat.com>
The previous patch introduced a new overload of gdbarch_return_value.
The intent here is that this new overload always be called by the core
of gdb -- the previous implementation is effectively deprecated,
because a call to the old-style method will not work with any
converted architectures (whereas calling the new-style method is will
delegate when needed).
This patch changes gdbarch.py so that the old gdbarch_return_value
wrapper function can be omitted. This will prevent any errors from
creeping in.
The gdbarch "return_value" can't correctly handle variably-sized
types. The problem here is that the TYPE_LENGTH of such a type is 0,
until the type is resolved, which requires reading memory. However,
gdbarch_return_value only accepts a buffer as an out parameter.
Fixing this requires letting the implementation of the gdbarch method
resolve the type and return a value -- that is, both the contents and
the new type.
After an attempt at this, I realized I wouldn't be able to correctly
update all implementations (there are ~80) of this method. So,
instead, this patch adds a new method that falls back to the current
method, and it updates gdb to only call the new method. This way it's
possible to incrementally convert the architectures that I am able to
test.
This commit is the result of running the gdb/copyright.py script,
which automated the update of the copyright year range for all
source files managed by the GDB project to be updated to include
year 2023.
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>
Use as many tabs as possible for indentation and pad with spaces to keep
the argument aligned to the opening parenthesis in the line above.
Co-developed-by: Simon Marchi <simon.marchi@efficios.com>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
Use tab for the first eight spaces of indentation, and align the gdb_printf
arguments to the open parenthesis of the function call.
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.
Currently, every internal_error call must be passed __FILE__/__LINE__
explicitly, like:
internal_error (__FILE__, __LINE__, "foo %d", var);
The need to pass in explicit __FILE__/__LINE__ is there probably
because the function predates widespread and portable variadic macros
availability. We can use variadic macros nowadays, and in fact, we
already use them in several places, including the related
gdb_assert_not_reached.
So this patch renames the internal_error function to something else,
and then reimplements internal_error as a variadic macro that expands
__FILE__/__LINE__ itself.
The result is that we now should call internal_error like so:
internal_error ("foo %d", var);
Likewise for internal_warning.
The patch adjusts all calls sites. 99% of the adjustments were done
with a perl/sed script.
The non-mechanical changes are in gdbsupport/errors.h,
gdbsupport/gdb_assert.h, and gdb/gdbarch.py.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
Change-Id: Ia6f372c11550ca876829e8fd85048f4502bdcf06
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.
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.
gdbarch implements its own registry-like approach. This patch changes
it to instead use registry.h. It's a rather large patch but largely
uninteresting -- it's mostly a straightforward conversion from the old
approach to the new one.
The main benefit of this change is that it introduces type safety to
the gdbarch registry. It also removes a bunch of code.
One possible drawback is that, previously, the gdbarch registry
differentiated between pre- and post-initialization setup. This
doesn't seem very important to me, though.
After the commit:
commit 08106042d9
Date: Thu May 19 13:20:17 2022 +0100
gdb: move the type cast into gdbarch_tdep
GDB would no longer build using g++ 4.8. The issue appears to be some
confusion caused by GDB having 'struct gdbarch_tdep', but also a
templated function called 'gdbarch_tdep'. Prior to the above commit
the gdbarch_tdep function was not templated, and this compiled just
fine. Note that the above commit compiles just fine with later
versions of g++, so this issue was clearly fixed at some point, though
I've not tried to track down exactly when.
In this commit I propose to fix the g++ 4.8 build problem by renaming
'struct gdbarch_tdep' to 'struct gdbarch_tdep_base'. This rename
better represents that the struct is only ever used as a base class,
and removes the overloading of the name, which allows GDB to build
with g++ 4.8.
I've also updated the comment on 'struct gdbarch_tdep_base' to fix a
typo, and the comment on the 'gdbarch_tdep' function, to mention that
in maintainer mode a run-time type check is performed.
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.
Now that filtered and unfiltered output can be treated identically, we
can unify the printf family of functions. This is done under the name
"gdb_printf". Most of this patch was written by script.
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 moves the copyright code from gdbarch.py to a new Python source
file, gdbcopyright.py. The function in this file will find the
copyright dates by scanning the calling script. This will be reused
in a future patch.
This involved minor changes to the output of gdbarch.py. Also, I've
updated copyright.py to remove the reference to gdbarch.sh. We don't
need to mention gdbarch.py there, either.
This changes gdbarch dumping to use filtered output. This seems a bit
better to me, both on the principle that this is an ordinary command,
and because the output can be voluminous, so it may be nice to stop in
the middle.
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.
This changes gdbarch.sh so that it no longer sorts the fields in
gdbarch_dump. This sorting isn't done anywhere else by gdbarch.sh,
and this simplifies the new generator a little bit.
While I think it makes sense to generate gdbarch.c, at the same time I
think it is better for ordinary code to be editable in a C file -- not
as a hunk of C code embedded in the generator.
This patch moves this sort of code out of gdbarch.sh and gdbarch.c and
into arch-utils.c, then has arch-utils.c include gdbarch.c.
Add aliases read_core_file_mappings_loop_ftype and
read_core_file_mappings_pre_loop_ftype. Intended for use with
read_core_file_mappings.
Also add build_id parameter to read_core_file_mappings_loop_ftype.
I noticed that gdbarch_selftest::operator() leaked the value returned by
gdbarch_printable_names. Make gdbarch_printable_names return an
std::vector and update callers. That makes it easier for everyone
involved, less manual memory management.
Change-Id: Ia8fc028bdb91f787410cca34f10bf3c5a6da1498
This field is not actually used, remove it.
gdb/ChangeLog:
* gdbarch.sh (struct gdbarch_info) <tdep_info>: Remove.
(gdbarch_find_by_info): Remove print.
* gdbarch.c, gdbarch.h: Re-generate.
Change-Id: I00af4681b8e1a27727441cbadc3827f5914bd8eb
This variable was made static in:
6bd434d6ca ("gdb: make some variables static")
But I modified gdbarch.c instead of gdbarch.sh, so the change was
later reverted when gdbarch.c was re-generated.
Do it right this time.
gdb/ChangeLog:
* gdbarch.sh (gdbarch_data_registry): Make static.
* gdbarch.c: Re-generate.
Change-Id: I4048ba99a0cf47acd9da050934965db222fbd159
We need some new gdbarch hooks to help us manipulate memory tags without having
to have GDB call the target methods directly.
This patch adds the following hooks:
gdbarch_memtag_to_string
--
Returns a printable string corresponding to the tag.
gdbarch_tagged_address_p
--
Checks if a particular address is protected with memory tagging.
gdbarch_memtag_matches_p
--
Checks if the logical tag of a pointer and the allocation tag from the address
the pointer points to matches.
gdbarch_set_memtags:
--
Sets either the allocation tag or the logical tag for a particular value.
gdbarch_get_memtag:
--
Gets either the allocation tag or the logical tag for a particular value.
gdbarch_memtag_granule_size
--
Sets the memory tag granule size, which represents the number of bytes a
particular allocation tag covers. For example, this is 16 bytes for
AArch64's MTE.
I've used struct value as opposed to straight CORE_ADDR so other architectures
can use the infrastructure without having to rely on a particular type for
addresses/pointers. Some architecture may use pointers of 16 bytes that don't
fit in a CORE_ADDR, for example.
gdb/ChangeLog:
2021-03-24 Luis Machado <luis.machado@linaro.org>
* arch-utils.c (default_memtag_to_string, default_tagged_address_p)
(default_memtag_matches_p, default_set_memtags)
(default_get_memtag): New functions.
* arch-utils.h (default_memtag_to_string, default_tagged_address_p)
(default_memtag_matches_p, default_set_memtags)
(default_get_memtag): New prototypes.
* gdbarch.c: Regenerate.
* gdbarch.h: Regenerate.
* gdbarch.sh (memtag_to_string, tagged_address_p, memtag_matches_p)
(set_memtags, get_memtag, memtag_granule_size): New gdbarch hooks.
(enum memtag_type): New enum.
