When compiling Newlib for arm targets with GCC 12.1 onward, the
passing of architecture extension information to the assembler is
automatic, making the use of .fpu and .arch_extension directives
in assembly files redundant.
With older versions of GCC, however, these directives must be
hard-coded into the `arm/setjmp.S' file to allow the assembly of
instructions concerning the storage and subsequent reloading of the
floating point registers to/from the jump buffer, respectively.
This patch conditionally adds the `.fpu vfpxd' and `.arch_extension
mve' directives based on compile-time preprocessor macros concerning
GCC version and target architectural features, such that both the
assembly and linking of setjmp.S succeeds for older versions of
Newlib.
The libgloss port has been reaching back into newlib internals for a
single header whose contents have been frozen for almost a decade.
To break this backwards libgloss->newlib dependency, move the acle
header to the srcroot include/ so everyone can use the same copy.
Add function prologue/epilogue to conditionally add BTI landing pads
and/or PAC code generation & authentication instructions depending on
compilation flags. Save the PAC value in the jump buffer so that
longjmp can only return to the authenticated location.
Add function prologue/epilogue to conditionally add BTI landing pads
and/or PAC code generation & authentication instructions depending on
compilation flags.
This patch enables PACBTI for all relevant variants of strlen:
* Newlib for armv8.1-m.main+pacbti
* Newlib for armv8.1-m.main+pacbti+mve
* Newlib-nano
Add function prologue/epilogue to conditionally add BTI landing pads
and/or PAC code generation & authentication instructions depending on
compilation flags.
This patch enables PACBTI for all relevant variants of strcmp:
* Newlib for armv8.1-m.main+pacbti
* Newlib for armv8.1-m.main+pacbti+mve
* Newlib-nano
Augment the arm_asm.h header file to simplify function prologues and
epilogues whilst adding support for PACBTI enablement via macros for
hand-written assembly functions. For PACBTI, both prologues/epilogues
as well as cfi-related directives are automatically amended
accordingly, depending on the compile-time mbranch-protection argument
values.
It defines the following preprocessor macros:
* HAVE_PAC_LEAF: Indicates whether pac-signing has been requested for
leaf functions.
* PAC_LEAF_PUSH_IP: Whether leaf functions should push the pac code
to the stack irrespective of whether the ip register is clobbered in
the function or not.
* STACK_ALIGN_ENFORCE: Whether a dummy register should be added to
the push list as necessary in the prologue to ensure stack
alignment preservation at the start of assembly function. The
epilogue behavior is likewise affected by this flag, ensuring any
pushed dummy registers also get popped on function return.
It also defines the following assembler macros:
* prologue: In addition to pushing any callee-saved registers onto
the stack, it generates any requested pacbti instructions.
Pushed registers are specified via the optional `first', `last',
`push_ip' and `push_lr' macro argument parameters.
when a single register number is provided, it pushes that
register. When two register numbers are provided, they specify a
rage to save. If push_ip and/or push_lr are non-zero, the
respective registers are also saved. Stack alignment is requested
via the `align` argument, which defaults to the value of
STACK_ALIGN_ENFORCE, unless manually overridden.
For example:
prologue push_ip=1 -> push {ip}
prologue push_ip=1, align8=1 -> push {r2, ip}
prologue push_ip=1, push_lr=1 -> push {ip, lr}
prologue 1 -> push {r1}
prologue 1, align8=1 -> push {r0, r1}
prologue 1 push_ip=1 -> push {r1, ip}
prologue 1 4 -> push {r1-r4}
prologue 1 4 push_ip=1 -> push {r1-r4, ip}
* epilogue: pops registers off the stack and emits pac key signing
instruction, if requested. The `first', `last', `push_ip',
`push_lr' and `align' function as per the prologue macro,
generating pop instead of push instructions.
Stack alignment is enforced via the following helper macro
call-chain:
{prologue|epilogue} ->_align8 -> _preprocess_reglist ->
_preprocess_reglist1 -> {_prologue|_epilogue}
Finally, the necessary cfi directives for adding debug information
to prologue and epilogue are generated via the following macros:
* cfisavelist - prologue macro helper function, generating
necessary .cfi_offset directives associated with push instruction.
Therefore, the net effect of calling `prologue 1 2 push_ip=1' is
to generate the following:
push {r1-r2, ip}
.cfi_adjust_cfa_offset 12
.cfi_offset 143, -4
.cfi_offset 2, -8
.cfi_offset 1, -12
* cfirestorelist - epilogue macro helper function, emitting
.cfi_restore instructions prior to resetting the cfa offset. As
such, calling `epilogue 1 2 push_ip=1' will produce:
pop {r1-r2, ip}
.cfi_register 143, 12
.cfi_restore 2
.cfi_restore 1
.cfi_def_cfa_offset 0
As per the arm Procedure Call Standard for the Arm Architecture
section 6.1.2 [1], VFP registers s16-s31 (d8-d15, q4-q7) must be
preserved across subroutine calls.
The current setjmp/longjmp implementations preserve only the core
registers, with the jump buffer size too small to store the required
co-processor registers.
In accordance with the C Library ABI for the Arm Architecture
section 6.11 [2], this patch sets _JBTYPE to long long adjusting
_JBLEN to 20.
It also emits vfp load/store instructions depending on architectural
support, predicated at compile time on ACLE feature-test macros.
[1] https://github.com/ARM-software/abi-aa/blob/main/aapcs32/aapcs32.rst
[2] https://github.com/ARM-software/abi-aa/blob/main/clibabi32/clibabi32.rst
Convert all the libc/ subdir makes into the top-level Makefile. This
allows us to build all of libc from the top Makefile without using any
recursive make calls. This is faster and avoids the funky lib.a logic
where we unpack subdir archives to repack into a single libc.a. The
machine override logic is maintained though by way of Makefile include
ordering, and source file accumulation in libc_a_SOURCES.
There's a few dummy.c files that are no longer necessary since we aren't
doing the lib.a accumulating, so punt them.
The winsup code has been pulling the internal newlib ssp library out,
but that doesn't exist anymore, so change that to pull the objects.
This kills off the last configure script under libc/ and folds it
into the top newlib configure script. The a lot of the logic was
already in the top configure script, so move what's left into a
libc/acinclude.m4 file.
The crt0.o was handled in a subdir-by-subdir basis: it would be compiled
in one (e.g. libc/sys/$arch/), then copied up one level (libc/sys/), then
copied up another (libc/) before finally being copied & installed in the
top newlib dir. The libc/sys/ copy was cleaned up, and then the top dir
was changed to copy it directly out of the libc/sys/$arch/ dir. But the
libc/sys/ copy to libc/ was left behind. Clean that up now too.
This is used in a bunch of places, but nowhere is it ever set, and
nowhere can I find any documentation, nor can I find any other project
using it. So delete the flags to simplify.
This was only ever used for i?86-pc-linux-gnu targets, but that's been
broken for years, and has since been dropped. So clean this up too.
This also deletes the funky objectlist logic since it only existed for
the libtool libraries. Since it was the only thing left in the small
Makefile.shared file, we can punt that too.
Now that we use AC_NO_EXECUTABLES, and we require a recent version of
autoconf, we don't need to define our own copies of these macros. So
switch to the standard AC_PROG_CC.
THe stdio subdir is actually required by the documentation. The
stdio/def is handled dynamically, but libc.texi always expects it
to be included, and fails if it isn't. So making it required when
building docs is safe.
The xdr subdir is handled dynamically, but it doesn't include any
docs, so the dynamic logic isn't (currently) adding any value. So
making it required when building docs is safe.
That leaves: iconv, stdio64, posix, and signal subdirs. The chapters
have a little disclaimer saying they are system-dependent, but even
then, imo having stable manuals regardless of the target is preferable,
and we can add more disclaimer language to these chapters if we want.
This doesn't touch the man page codepaths, just the info/pdf.
When using the top-level configure script but subdir Makefiles, the
newlib_basedir value gets a bit out of sync: it's relative to where
configure lives, not where the Makefile lives. Move the abs setting
from the top-level configure script into acinclude.m4 so we can rely
on it being available everywhere. Although this commit doesn't use
it anywhere, just lays the groundwork.
The machine configure scripts are all effectively stub scripts that
pass the higher level options to its own makefile. There were only
three doing custom tests. The rest were all effectively the same as
the libc/ configure script.
So instead of recursively running configure in all of these subdirs,
generate their makefiles from the top-level configure. For the few
unique ones, deploy a pattern of including subdir logic via m4:
m4_include([machine/nds32/acinclude.m4])
Some of the generated machine makefiles have a bunch of extra stuff
added to them, but that's because they were inconsistent in their
configure libtool calls. The top-level has it, so it exports some
new vars to the ones that weren't already.
It's unclear why this was added originally, but assuming it was needed
20 years ago, it shouldn't be explicitly required nowadays. Current
versions of autotools already take care of exporting LDFLAGS to the
Makefile as needed (things are actually getting linked). That's why
the configure diffs show LDFLAGS still here, but shifted to a diff
place in the output list. A few dirs stop exporting LDFLAGS, but
that's because they don't do any linking, only compiling, so it's
correct.
As for the use of $ldflags instead of the standard $LDFLAGS, I can't
really explain that at all. Just use the right name so users don't
have to dig into why their setting isn't respected, and then use a
non-standard name instead. Adjust the testsuite to match.
Since AM_INIT_AUTOMAKE calls AC_PROG_AWK, and some configure.ac
scripts call it too, we end up testing for awk multiple times. If
we change NEWLIB_CONFIGURE to require the macro instead, then it
makes sure it's always expanded, but only once.
While we're here, do the same thing with AC_PROG_INSTALL since it
is also called by AM_INIT_AUTOMAKE, although it doesn't currently
result in duplicate configure checks.
Since automake already sets per-library CCASFLAGS to $(AM_CCASFLAGS)
by default, there's no need to explicitly set it here.
Many of these dirs don't have .S files in the first place, so the rule
doesn't even do anything. That can easily be seen when Makefile.in has
no changes as a result.
For the dirs with .S files, the custom rules are the same as the pattern
.S.o rules, so this is a nice cleanup.
The only dir that was adding extra flags (newlib/libc/machine/mn10300/)
to the per-library setting can have it moved to the global AM_CCASFLAGS
since the subdir only has one target. Although the setting just adds
extra debugging flags, so maybe it should be deleted in general.
There are a few dirs that we leave the redundant setting in place. This
is to workaround an automake limitation in subdirs that support building
with & w/out libtool:
https://www.gnu.org/software/automake/manual/html_node/Objects-created-both-with-libtool-and-without.html
This matches what the other GNU toolchain projects have done already.
The generated diff in practice isn't terribly large. This will allow
more use of subdir local.mk includes due to fixes & improvements that
came after the 1.11 release series.
The newlib & libgloss dirs are already generated using autoconf-2.69.
To avoid merging new code and/or accidental regeneration using diff
versions, leverage config/override.m4 to pin to 2.69 exactly. This
matches what gcc/binutils/gdb are already doing.
The README file already says to use autoconf-2.69.
To accomplish this, it's just as simple as adding -I flags to the
top-level config/ dir when running aclocal. This is because the
override.m4 file overrides AC_INIT to first require the specific
autoconf version before calling the real AC_INIT.
The configure scripts were regenerated with 2.69 for the newlib-4.2.0
release in 484d2ebf8d, but the aclocal
files were not. Do that now to avoid confusion between the two as to
which version of autoconf was used.
Since automake deprecated the INCLUDES name in favor of AM_CPPFLAGS,
change all existing users over. The generated code is the same since
the two variables have been used in the same exact places by design.
There are other cleanups to be done, but lets focus on just renaming
here so we can upgrade to a newer automake version w/out triggering
new warnings.
The 'cygnus' option was removed from automake 1.13 in 2012, so the
presence of this option prevents that or a later version of automake
being used.
A check-list of the effects of '--cygnus' from the automake 1.12
documentation, and steps taken (where possible) to preserve those
effects (See also this thread [1] for discussion on that):
[1] https://lists.gnu.org/archive/html/bug-automake/2012-03/msg00048.html
1. The foreign strictness is implied.
Already present in AM_INIT_AUTOMAKE in newlib/acinclude.m4
2. The options no-installinfo, no-dependencies and no-dist are implied.
Already present in AM_INIT_AUTOMAKE in newlib/acinclude.m4
Future work: Remove no-dependencies and any explicit header dependencies,
and use automatic dependency tracking instead. Are there explicit rules
which are now redundant to removing no-installinfo and no-dist?
3. The macro AM_MAINTAINER_MODE is required.
Already present in newlib/acinclude.m4
Note that maintainer-mode is still disabled by default.
4. Info files are always created in the build directory, and not in the
source directory.
This appears to be an error in the automake documentation describing
'--cygnus' [2]. newlib's info files are generated in the source
directory, and no special steps are needed to keep doing that.
[2] https://lists.gnu.org/archive/html/bug-automake/2012-04/msg00028.html
5. texinfo.tex is not required if a Texinfo source file is specified.
(The assumption is that the file will be supplied, but in a place that
automake cannot find.)
This effect is overriden by an explicit setting of the TEXINFO_TEX
variable (the directory part of which is fed into texi2X via the
TEXINPUTS environment variable).
6. Certain tools will be searched for in the build tree as well as in the
user's PATH. These tools are runtest, expect, makeinfo and texi2dvi.
For obscure automake reasons, this effect of '--cygnus' is not active
for makeinfo in newlib's configury.
However, there appears to be top-level configury which selects in-tree
runtest, expect and makeinfo, if present. So, if that works as it
appears, this effect is preserved. If not, this may cause problem if
anyone is building those tools in-tree.
This effect is not preserved for texi2dvi. This may cause problems if
anyone is building texinfo in-tree.
If needed, explicit checks for those tools looking in places relative to
$(top_srcdir)/../ as well as in PATH could be added.
7. The check target doesn't depend on all.
This effect is not preseved. The check target now depends on the all
target.
This concern seems somewhat academic given the current state of the
testsuite.
Also note that this doesn't touch libgloss.
The Cortex-R52 processor is an Armv8-R processor with a NEON unit. This
fix prevents conflicting architecture profiles A/R errors issued by the
linker.
Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>
The previous fenv support for ARM used the soft-float implementation of
FreeBSD. Newlib uses the one from libgcc by default. They are not
compatible. Having an GCC incompatible soft-float fenv support in
Newlib makes no sense. A long-term solution could be to provide a
libgcc compatible soft-float support. This likely requires changes in
the GCC configuration. For now, provide a stub implementation for
soft-float multilibs similar to RISC-V.
Move implementation to one file and delete now unused files. Hide
implementation details. Remove function parameter names from header
file to avoid name conflicts.
Provide VFP support if __SOFTFP__ is not defined like glibc.
Reviewed-by: Sebastian Huber <sebastian.huber@embedded-brains.de>
Signed-off-by: Eshan dhawan <eshandhawan51@gmail.com>
Most code in newlib already uses unified syntax, but just a couple of
laggards remain. This patch removes these and means the the entire
code base has now been converted.
Victor L. Do Nascimento
Mike Frysinger
Jeff Johnston
Jon Turney
Sebastian Huber
Eshan dhawan
Eshan dhawan via Newlib
Richard Earnshaw
Christos Gentsos