in thumb mode, r7 is the ABI frame pointer register, and unless frame
pointer is disabled, gcc insists on treating it as a fixed register,
refusing to spill it to satisfy constraints. unfortunately, r7 is also
used in the syscall ABI for passing the syscall number.
up til now we just treated this as a requirement to disable frame
pointer when generating code as thumb, but it turns out gcc forcibly
enables frame pointer, and the fixed register constraint that goes
with it, for functions which contain VLAs. this produces an
unacceptable arch-specific constraint that (non-arm-specific) source
files making syscalls cannot use VLAs.
as a workaround, avoid r7 register constraints when producing thumb
code and instead save/restore r7 in a temp register as part of the asm
block. at some point we may want/need to support armv6-m/thumb1, so
the asm has been tweaked to be thumb1-compatible while also
near-optimal for thumb2: it allows the temp and/or syscall number to
be in high registers (necessary since r0-r5 may all be used for
syscalll args) and in thumb2 mode allows the syscall number to be an
8-bit immediate.
__ARM_ARCH_6ZK__ is a gcc specific historical typo which may not be
defined by other compilers.
https://gcc.gnu.org/ml/gcc-patches/2015-07/msg02237.html
To avoid unexpected results when building for ARMv6KZ with clang, the
correct form of the macro (ie 6KZ) needs to be tested. The incorrect
form of the macro (ie 6ZK) still needs to be tested for compatibility
with pre-2015 versions of gcc.
Provide an ARM specific a_ctz_32 helper function for architecture
versions for which it can be implemented efficiently via the "rbit"
instruction (ie all Thumb-2 capable versions of ARM v6 and above).
Update atomic.h to provide a_ctz_l in all cases (atomic_arch.h should
now only provide a_ctz_32 and/or a_ctz_64).
The generic version of a_ctz_32 now takes advantage of a_clz_32 if
available and the generic a_ctz_64 now makes use of a_ctz_32.
the output delay features (NL*, CR*, TAB*, BS*, and VT*) are
XSI-shaded. VT* is in the V* namespace reservation but the rest need
to be suppressed in base POSIX namespace.
unfortunately this change introduces feature test macro checks into
another bits header. at some point these checks should be simplified
by having features.h handle the "FTM X implies Y" relationships.
PAGESIZE is actually the version defined in POSIX base, with PAGE_SIZE
being in the XSI option. use PAGESIZE as the underlying definition to
facilitate making exposure of PAGE_SIZE conditional.
HWCAP_SVE is new in linux commit 43994d824e8443263dc98b151e6326bf677be52e
HWCAP_SHA3, HWCAP_SM3, HWCAP_SM4, HWCAP_ASIMDDP and HWCAP_SHA512 are new in
f5e035f8694c3bdddc66ea46ecda965ee6853718
PPC_FEATURE2_HTM_NO_SUSPEND is new in linux commit
cba6ac4869e45cc93ac5497024d1d49576e82666
PPC_FEATURE2_DARN and PPC_FEATURE2_SCV were new in v4.12 in commit
a4700a26107241cc7b9ac8528b2c6714ff99983d
for synchronous page faults, new in linux commit
1c9725974074a047f6080eecc62c50a8e840d050 and
b6fb293f2497a9841d94f6b57bd2bb2cd222da43
note that only targets that use asm-generic/mman.h have this new
flag defined, so undef it on other targets (mips*, powerpc*).
use the same token to define TIOCSER_TEMT as is used in ioctl.h
so when both headers are included there are no redefinition warnings
during musl build.
s390 can use the generic ioctls definitions other than FIOQSIZE (like arm).
this fixes some missing ioctls and two incorrect ones:
TIOCTTYGSTRUCT and TIOCM_MODEM_BITS seem to be defined on frv
target only in linux.
hwcap bits for armv8.3 extensions, added in linux commits
c8c3798d2369e4285da44b244638eafe446a8f8a
cb567e79fa504575cb97fb2f866d2040ed1c92e7
c651aae5a7732287c1c9bc974ece4ed798780544
commit 06fbefd100 (first included in
release 1.1.17) introduced this regression.
patch by Adrian Bunk. it fixes the regression in all cases, but
spuriously prevents use of the clz instruction on very old compiler
versions that don't define __ARM_ARCH. this may be fixed in a more
general way at some point in the future. it also omits thumb1 logic
since building as thumb1 code is currently not supported.
most of the found naming differences don't matter to musl, because
internally it unifies the syscall names that vary across targets,
but for external code the names should match the kernel uapi.
aarch64:
__NR_fstatat is called __NR_newfstatat in linux.
__NR_or1k_atomic got mistakenly copied from or1k.
arm:
__NR_arm_sync_file_range is an alias for __NR_sync_file_range2
__NR_fadvise64_64 is called __NR_arm_fadvise64_64 in linux,
the old non-arm name is kept too, it should not cause issues.
(powerpc has similar nonstandard fadvise and it uses the
normal name.)
i386:
__NR_madvise1 was removed from linux in commit
303395ac3bf3e2cb488435537d416bc840438fcb 2011-11-11
microblaze:
__NR_fadvise, __NR_fstatat, __NR_pread, __NR_pwrite
had different name in linux.
mips:
__NR_fadvise, __NR_fstatat, __NR_pread, __NR_pwrite, __NR_select
had different name in linux.
mipsn32:
__NR_fstatat is called __NR_newfstatat in linux.
or1k:
__NR__llseek is called __NR_llseek in linux.
the old name is kept too because that's the name musl uses
internally.
powerpc:
__NR_{get,set}res{gid,uid}32 was never present in powerpc linux.
__NR_timerfd was briefly defined in linux but then got renamed.
Glibc renamed the linux uapi HWCAP_* macros to HWCAP_ARM_*
so have both variants in case some code depends on it.
(The HWCAP2_ macros are not defined in glibc currently so those
only have the linux uapi variant.)
counts leading zero bits of a 64bit int, undefined on zero input.
(has nothing to do with atomics, added to atomic.h so target specific
helper functions are together.)
there is a logarithmic generic implementation and another in terms of
a 32bit a_clz_32 on targets where that's available.
it is defined in linux asm/sockios.h since commit
ae40eb1ef30ab4120bd3c8b7e3da99ee53d27a23 (linux v2.6.22)
but was missing from musl by accident.
in musl the sockios macros are exposed in sys/ioctl.h together
with other ioctl requests instead of in sys/socket.h because of
namespace rules. (glibc has them in sys/socket.h under _GNU_SOURCE.)
Due to a missing ":" in an asm() statement, the "memory" clobber is
considered by gcc as an input operand and not a clobber, which causes a
build failure.
at one point, clang reportedly failed to support the asm register
constraints needed for inline syscalls. versions of clang that old
have much bigger problems that preclude using them to compile musl
libc.
mips64 requires 'struct stat' conversion due to incorrect 32-bit
fields where time_t should be in the kernel version of the structure.
syscall_arch.h already performed the correct translation for stat,
fstat, and lstat syscalls, but omitted special handling for fstatat.
This structure was missed when creating the s390x port.
This is based on the report and patch from William Pitcock, but with a
modified structure defintion to more closely match the kernel's
definition.
Including sys/procfs.h complains unknown type name 'fpreg_t' in
bits/user.h. fpreg_t in bits/signal.h and elf_fpreg_t in bits/user.h
are practically the same.
per_struct is never used, even conflicts with kernel header
asm/ptrace.h
the 32-bit pc-relative address for stage 2 of dynamic linker entry was
wrongly loaded with a zero-extending load instead of sign-extending
load, resulting in an invalid jump if the offset happened to be
negative, which depends on the linker's ordering of text sections.
the ABI for arm was silently changed at some point to allow page sizes
other than 4k; traditional binaries built with only 4k-aligned offsets
between load segments cannot run on such systems, but newer binutils
versions use 64k offset alignment.
while larger page size is undesirable for various reasons, users have
encountered hardware and/or kernels that lock the page size to a
larger value, so follow the new ABI and allow it to vary.
when _GNU_SOURCE is defined, which is always the case when compiling
c++ with gcc, these macros for the the indices in gregset_t are
exposed and likely to clash with applications. by using enum constants
rather than macros defined with integer literals, we can make the
clash slightly less likely to break software. the macros are still
defined in case anything checks for them with #ifdef, but they're
defined to expand to themselves so that non-file-scope (e.g.
namespaced) identifiers by the same names still work.
for the sake of avoiding mistakes, the changes were generated with sed
via the command:
sed -i -e 's/#define *\(REG_[A-Z_0-9]\{1,\}\) *\([0-9]\{1,\}\)'\
'/enum { \1 = \2 };\n#define \1 \1/' \
arch/i386/bits/signal.h arch/x86_64/bits/signal.h arch/x32/bits/signal.h
three problems are addressed:
- use of pc arithmetic, which was difficult if not impossible to make
correct in thumb mode on all models, so that relative rather than
absolute pointers to the backends could be used. this was designed
back when there was no coherent model for the early stages of the
dynamic linker before relocations, and is no longer necessary.
- assumption that data (the relative pointers to the backends) can be
accessed at a constant displacement from the code. this will not be
possible on future fdpic subarchs (for cortex-m), so move
responsibility for loading the backend code address to the caller.
- hard-coded arm opcodes using the .word directive. instead, use the
.arch directive to work around the assembler's refusal to assemble
instructions not available (or in some cases, available but just
considered deprecated) in the target isa level. the obscure v6t2
arch is used for v6 code so as to (1) allow generation of thumb2
output if -mthumb is active, and (2) avoid warnings/errors for mcr
barriers that clang would produce if we just set arch to v7-a.
in addition, the __aeabi_read_tp function is moved out of the inner
workings and implemented as an asm wrapper around a C function, so
that asm code does not need to read global data. the asm wrapper
serves to satisfy the ABI calling convention requirements for this
function.
