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/* PLT trampolines. ARM/NaCl version.
Copyright (C) 2013 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, see
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
.syntax unified
.text
@ Change &GOT[n+3] into 8*n. Note relocs are 8 bytes each.
.macro compute_reloc_arg pltgot, got2
sub r1, \pltgot, \got2 @ r1 = &GOT[n+3] - &GOT[2] = 4*(n-1)
sub r1, r1, #4 @ r1 = 4*n
add r1, r1, r1 @ r1 *= 2 = 8*n
.endm
CFI_SECTIONS
.globl _dl_runtime_resolve
.type _dl_runtime_resolve, %function
.p2align 4
_dl_runtime_resolve:
cfi_startproc
cfi_adjust_cfa_offset (8)
@ We get called with:
@ lr contains the return address from this call
@ stack[1] contains &GOT[n+3] (pointer to function)
@ stack[0] points to &GOT[2]
ldr ip, [sp] @ ip gets &GOT[2]
@ Save the argument registers and the return address.
@ r4 doesn't need to be saved, but it makes the total
@ adjustment to sp (including the two words pushed by
@ the PLT code) an even eight words, so sp stays aligned.
push {r0-r4, lr}
cfi_adjust_cfa_offset (24)
cfi_rel_offset (r0, 0)
cfi_rel_offset (r1, 4)
cfi_rel_offset (r2, 8)
cfi_rel_offset (r3, 12)
cfi_rel_offset (r4, 16)
cfi_rel_offset (lr, 20)
ldr r1, [sp, #28] @ r1 gets &GOT[n+3]
@ Get the 'struct link_map *' for the first argument to _dl_fixup.
sfi_breg ip, ldr r0, [\B, #-4]
@ Get the reloc offset for the second argument to _dl_fixup.
compute_reloc_arg r1, ip
@ This does the real work, and returns the real call target.
sfi_bl _dl_fixup
mov ip, r0
@ Restore the saved registers.
pop {r0-r4, lr}
cfi_adjust_cfa_offset (-24)
cfi_restore (r0)
cfi_restore (r1)
cfi_restore (r2)
cfi_restore (r3)
cfi_restore (r4)
cfi_restore (lr)
@ Now compensate for the two words pushed by the PLT code.
sfi_sp add sp, #8
cfi_adjust_cfa_offset (-8)
@ Finally, jump to the newfound call target.
sfi_bx ip
cfi_endproc
.size _dl_runtime_resolve, .-_dl_runtime_resolve
#ifndef PROF
.globl _dl_runtime_profile
.type _dl_runtime_profile, #function
.p2align 4
_dl_runtime_profile:
cfi_startproc
cfi_adjust_cfa_offset (8)
@ XXX tbd
sfi_trap
cfi_endproc
.size _dl_runtime_profile, .-_dl_runtime_profile
#endif
.previous
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