diff options
Diffstat (limited to 'sysdeps/x86_64/dl-tlsdesc.S')
| -rw-r--r-- | sysdeps/x86_64/dl-tlsdesc.S | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S new file mode 100644 index 0000000000..5eac1f2a5b --- /dev/null +++ b/sysdeps/x86_64/dl-tlsdesc.S @@ -0,0 +1,245 @@ +/* Thread-local storage handling in the ELF dynamic linker. x86_64 version. + Copyright (C) 2004, 2005, 2008 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <sysdep.h> +#include <tls.h> +#include "tlsdesc.h" + + .text + + /* This function is used to compute the TP offset for symbols in + Static TLS, i.e., whose TP offset is the same for all + threads. + + The incoming %rax points to the TLS descriptor, such that + 0(%rax) points to _dl_tlsdesc_return itself, and 8(%rax) holds + the TP offset of the symbol corresponding to the object + denoted by the argument. */ + + .hidden _dl_tlsdesc_return + .global _dl_tlsdesc_return + .type _dl_tlsdesc_return,@function + cfi_startproc + .align 16 +_dl_tlsdesc_return: + movq 8(%rax), %rax + ret + cfi_endproc + .size _dl_tlsdesc_return, .-_dl_tlsdesc_return + + /* This function is used for undefined weak TLS symbols, for + which the base address (i.e., disregarding any addend) should + resolve to NULL. + + %rax points to the TLS descriptor, such that 0(%rax) points to + _dl_tlsdesc_undefweak itself, and 8(%rax) holds the addend. + We return the addend minus the TP, such that, when the caller + adds TP, it gets the addend back. If that's zero, as usual, + that's most likely a NULL pointer. */ + + .hidden _dl_tlsdesc_undefweak + .global _dl_tlsdesc_undefweak + .type _dl_tlsdesc_undefweak,@function + cfi_startproc + .align 16 +_dl_tlsdesc_undefweak: + movq 8(%rax), %rax + subq %fs:0, %rax + ret + cfi_endproc + .size _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak + +#ifdef SHARED + .hidden _dl_tlsdesc_dynamic + .global _dl_tlsdesc_dynamic + .type _dl_tlsdesc_dynamic,@function + + /* %rax points to the TLS descriptor, such that 0(%rax) points to + _dl_tlsdesc_dynamic itself, and 8(%rax) points to a struct + tlsdesc_dynamic_arg object. It must return in %rax the offset + between the thread pointer and the object denoted by the + argument, without clobbering any registers. + + The assembly code that follows is a rendition of the following + C code, hand-optimized a little bit. + +ptrdiff_t +_dl_tlsdesc_dynamic (register struct tlsdesc *tdp asm ("%rax")) +{ + struct tlsdesc_dynamic_arg *td = tdp->arg; + dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET); + if (__builtin_expect (td->gen_count <= dtv[0].counter + && (dtv[td->tlsinfo.ti_module].pointer.val + != TLS_DTV_UNALLOCATED), + 1)) + return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset + - __thread_pointer; + + return __tls_get_addr_internal (&td->tlsinfo) - __thread_pointer; +} +*/ + cfi_startproc + .align 16 +_dl_tlsdesc_dynamic: + /* Preserve call-clobbered registers that we modify. + We need two scratch regs anyway. */ + movq %rsi, -16(%rsp) + movq %fs:DTV_OFFSET, %rsi + movq %rdi, -8(%rsp) + movq TLSDESC_ARG(%rax), %rdi + movq (%rsi), %rax + cmpq %rax, TLSDESC_GEN_COUNT(%rdi) + ja .Lslow + movq TLSDESC_MODID(%rdi), %rax + salq $4, %rax + movq (%rax,%rsi), %rax + cmpq $-1, %rax + je .Lslow + addq TLSDESC_MODOFF(%rdi), %rax +.Lret: + movq -16(%rsp), %rsi + subq %fs:0, %rax + movq -8(%rsp), %rdi + ret +.Lslow: + /* Besides rdi and rsi, saved above, save rdx, rcx, r8, r9, + r10 and r11. Also, align the stack, that's off by 8 bytes. */ + subq $72, %rsp + cfi_adjust_cfa_offset (72) + movq %rdx, 8(%rsp) + movq %rcx, 16(%rsp) + movq %r8, 24(%rsp) + movq %r9, 32(%rsp) + movq %r10, 40(%rsp) + movq %r11, 48(%rsp) + /* %rdi already points to the tlsinfo data structure. */ + call __tls_get_addr@PLT + movq 8(%rsp), %rdx + movq 16(%rsp), %rcx + movq 24(%rsp), %r8 + movq 32(%rsp), %r9 + movq 40(%rsp), %r10 + movq 48(%rsp), %r11 + addq $72, %rsp + cfi_adjust_cfa_offset (-72) + jmp .Lret + cfi_endproc + .size _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic +#endif /* SHARED */ + + /* This function is a wrapper for a lazy resolver for TLS_DESC + RELA relocations. The incoming 0(%rsp) points to the caller's + link map, pushed by the dynamic object's internal lazy TLS + resolver front-end before tail-calling us. We need to pop it + ourselves. %rax points to a TLS descriptor, such that 0(%rax) + holds the address of the internal resolver front-end (unless + some other thread beat us to resolving it) and 8(%rax) holds a + pointer to the relocation. + + When the actual resolver returns, it will have adjusted the + TLS descriptor such that we can tail-call it for it to return + the TP offset of the symbol. */ + + .hidden _dl_tlsdesc_resolve_rela + .global _dl_tlsdesc_resolve_rela + .type _dl_tlsdesc_resolve_rela,@function + cfi_startproc + .align 16 + /* The PLT entry will have pushed the link_map pointer. */ +_dl_tlsdesc_resolve_rela: + cfi_adjust_cfa_offset (8) + /* Save all call-clobbered registers. */ + subq $72, %rsp + cfi_adjust_cfa_offset (72) + movq %rax, (%rsp) + movq %rdi, 8(%rsp) + movq %rax, %rdi /* Pass tlsdesc* in %rdi. */ + movq %rsi, 16(%rsp) + movq 72(%rsp), %rsi /* Pass link_map* in %rsi. */ + movq %r8, 24(%rsp) + movq %r9, 32(%rsp) + movq %r10, 40(%rsp) + movq %r11, 48(%rsp) + movq %rdx, 56(%rsp) + movq %rcx, 64(%rsp) + call _dl_tlsdesc_resolve_rela_fixup + movq (%rsp), %rax + movq 8(%rsp), %rdi + movq 16(%rsp), %rsi + movq 24(%rsp), %r8 + movq 32(%rsp), %r9 + movq 40(%rsp), %r10 + movq 48(%rsp), %r11 + movq 56(%rsp), %rdx + movq 64(%rsp), %rcx + addq $80, %rsp + cfi_adjust_cfa_offset (-80) + jmp *(%rax) + cfi_endproc + .size _dl_tlsdesc_resolve_rela, .-_dl_tlsdesc_resolve_rela + + /* This function is a placeholder for lazy resolving of TLS + relocations. Once some thread starts resolving a TLS + relocation, it sets up the TLS descriptor to use this + resolver, such that other threads that would attempt to + resolve it concurrently may skip the call to the original lazy + resolver and go straight to a condition wait. + + When the actual resolver returns, it will have adjusted the + TLS descriptor such that we can tail-call it for it to return + the TP offset of the symbol. */ + + .hidden _dl_tlsdesc_resolve_hold + .global _dl_tlsdesc_resolve_hold + .type _dl_tlsdesc_resolve_hold,@function + cfi_startproc + .align 16 +_dl_tlsdesc_resolve_hold: +0: + /* Save all call-clobbered registers. */ + subq $72, %rsp + cfi_adjust_cfa_offset (72) + movq %rax, (%rsp) + movq %rdi, 8(%rsp) + movq %rax, %rdi /* Pass tlsdesc* in %rdi. */ + movq %rsi, 16(%rsp) + /* Pass _dl_tlsdesc_resolve_hold's address in %rsi. */ + leaq . - _dl_tlsdesc_resolve_hold(%rip), %rsi + movq %r8, 24(%rsp) + movq %r9, 32(%rsp) + movq %r10, 40(%rsp) + movq %r11, 48(%rsp) + movq %rdx, 56(%rsp) + movq %rcx, 64(%rsp) + call _dl_tlsdesc_resolve_hold_fixup +1: + movq (%rsp), %rax + movq 8(%rsp), %rdi + movq 16(%rsp), %rsi + movq 24(%rsp), %r8 + movq 32(%rsp), %r9 + movq 40(%rsp), %r10 + movq 48(%rsp), %r11 + movq 56(%rsp), %rdx + movq 64(%rsp), %rcx + addq $72, %rsp + cfi_adjust_cfa_offset (-72) + jmp *(%eax) + cfi_endproc + .size _dl_tlsdesc_resolve_hold, .-_dl_tlsdesc_resolve_hold |