When glibc is built with ISA level 3 or above enabled, SSE resolvers
aren't available and glibc fails to build:
ld: .../elf/librtld.os: in function `init_cpu_features':
.../elf/../sysdeps/x86/cpu-features.c:1200:(.text+0x1445f): undefined reference to `_dl_runtime_resolve_fxsave'
ld: .../elf/librtld.os: relocation R_X86_64_PC32 against undefined hidden symbol `_dl_runtime_resolve_fxsave' can not be used when making a shared object
/usr/local/bin/ld: final link failed: bad value
For ISA level 3 or above, don't use _dl_runtime_resolve_fxsave nor
_dl_tlsdesc_dynamic_fxsave.
This fixes BZ #31429.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
Compiler generates the following instruction sequence for GNU2 dynamic
TLS access:
leaq tls_var@TLSDESC(%rip), %rax
call *tls_var@TLSCALL(%rax)
or
leal tls_var@TLSDESC(%ebx), %eax
call *tls_var@TLSCALL(%eax)
CALL instruction is transparent to compiler which assumes all registers,
except for EFLAGS and RAX/EAX, are unchanged after CALL. When
_dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
path. __tls_get_addr is a normal function which doesn't preserve any
caller-saved registers. _dl_tlsdesc_dynamic saved and restored integer
caller-saved registers, but didn't preserve any other caller-saved
registers. Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
XSAVE and XSAVEC to save and restore all caller-saved registers. This
fixes BZ #31372.
Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
to optimize elf_machine_runtime_setup.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
_dl_tlsdesc_undefweak and _dl_tlsdesc_dynamic access the thread pointer
via the tcb field in TCB:
_dl_tlsdesc_undefweak:
_CET_ENDBR
movq 8(%rax), %rax
subq %fs:0, %rax
ret
_dl_tlsdesc_dynamic:
...
subq %fs:0, %rax
movq -8(%rsp), %rdi
ret
Since the tcb field in TCB is a pointer, %fs:0 is a 32-bit location,
not 64-bit. It should use "sub %fs:0, %RAX_LP" instead. Since
_dl_tlsdesc_undefweak returns ptrdiff_t and _dl_make_tlsdesc_dynamic
returns void *, RAX_LP is appropriate here for x32 and x86-64. This
fixes BZ #31185.
On x32, I got
FAIL: elf/tst-tlsgap
$ gdb elf/tst-tlsgap
...
open tst-tlsgap-mod1.so
Thread 2 "tst-tlsgap" received signal SIGSEGV, Segmentation fault.
[Switching to LWP 2268754]
_dl_tlsdesc_dynamic () at ../sysdeps/x86_64/dl-tlsdesc.S:108
108 movq (%rsi), %rax
(gdb) p/x $rsi
$4 = 0xf7dbf9005655fb18
(gdb)
This is caused by
_dl_tlsdesc_dynamic:
_CET_ENDBR
/* Preserve call-clobbered registers that we modify.
We need two scratch regs anyway. */
movq %rsi, -16(%rsp)
movq %fs:DTV_OFFSET, %rsi
Since the dtv field in TCB is a pointer, %fs:DTV_OFFSET is a 32-bit
location, not 64-bit. Load the dtv field to RSI_LP instead of rsi.
This fixes BZ #31184.
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 7061 files FOO.
I then removed trailing white space from math/tgmath.h,
support/tst-support-open-dev-null-range.c, and
sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following
obscure pre-commit check failure diagnostics from Savannah. I don't
know why I run into these diagnostics whereas others evidently do not.
remote: *** 912-#endif
remote: *** 913:
remote: *** 914-
remote: *** error: lines with trailing whitespace found
...
remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master
We need NO_RTLD_HIDDEN because of the need for PLT calls in ld.so.
See Roland's comment in
https://sourceware.org/bugzilla/show_bug.cgi?id=15605
"in the Hurd it's crucial that calls like __mmap be the libc ones
instead of the rtld-local ones after the bootstrap phase, when the
dynamic linker is being used for dlopen and the like."
We used to just avoid all hidden use in the rtld ; this commit switches to
keeping only those that should use PLT calls, i.e. essentially those defined in
sysdeps/mach/hurd/dl-sysdep.c:
__assert_fail
__assert_perror_fail
__*stat64
_exit
This fixes a few startup issues, notably the call to __tunable_get_val that is
made before PLTs are set up.
Since _dl_tlsdesc_dynamic is called via PLT, we need to add 8 bytes for
push in the PLT entry to align the stack.
[BZ #20309]
* configure.ac (have-mtls-dialect-gnu2): Set to yes if
-mtls-dialect=gnu2 works.
* configure: Regenerated.
* elf/Makefile [have-mtls-dialect-gnu2 = yes]
(tests): Add tst-gnu2-tls1.
(modules-names): Add tst-gnu2-tls1mod.
($(objpfx)tst-gnu2-tls1): New.
(tst-gnu2-tls1mod.so-no-z-defs): Likewise.
(CFLAGS-tst-gnu2-tls1mod.c): Likewise.
* elf/tst-gnu2-tls1.c: New file.
* elf/tst-gnu2-tls1mod.c: Likewise.
* sysdeps/x86_64/dl-tlsdesc.S (_dl_tlsdesc_dynamic): Add 8
bytes for push in the PLT entry to align the stack.
__tls_get_addr/___tls_get_addr is always defined in ld.so. There is
no need to call them via PLT inside ld.so. This patch adds the hidden
__tls_get_addr/___tls_get_addr aliases and calls them directly from
_dl_tlsdesc_dynamic. There is no need to set up the EBX register in
i386 _dl_tlsdesc_dynamic when calling the hidden ___tls_get_addr.
* elf/dl-tls.c (__tls_get_addr): Provide the hidden definition
if not defined.
* sysdeps/i386/dl-tls.h (___tls_get_addr): Provide the hidden
definition.
* sysdeps/i386/dl-tlsdesc.S (_dl_tlsdesc_dynamic): Call the
hidden ___tls_get_addr.
* sysdeps/x86_64/dl-tlsdesc.S (_dl_tlsdesc_dynamic): Call the
hidden __tls_get_addr.
* sysdeps/generic/localplt.data (__tls_get_addr): Removed.
* sysdeps/unix/sysv/linux/i386/localplt.data (___tls_get_addr):
Likewise.
