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/*
Copyright Oliver Kowalke 2009.
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
*/
/*******************************************************
* *
* ------------------------------------------------- *
* | 0 | 4 | 8 | 12 | 16 | 20 | 24 | 28 | *
* ------------------------------------------------- *
* |bchai|hiddn| fpscr | PC | CR | R14 | R15 | *
* ------------------------------------------------- *
* ------------------------------------------------- *
* | 32 | 36 | 40 | 44 | 48 | 52 | 56 | 60 | *
* ------------------------------------------------- *
* | R16 | R17 | R18 | R19 | R20 | R21 | R22 | R23 | *
* ------------------------------------------------- *
* ------------------------------------------------- *
* | 64 | 68 | 72 | 76 | 80 | 84 | 88 | 92 | *
* ------------------------------------------------- *
* | R24 | R25 | R26 | R27 | R28 | R29 | R30 | R31 | *
* ------------------------------------------------- *
* ------------------------------------------------- *
* | 96 | 100 | 104 | 108 | 112 | 116 | 120 | 124 | *
* ------------------------------------------------- *
* | F14 | F15 | F16 | F17 | *
* ------------------------------------------------- *
* ------------------------------------------------- *
* | 128 | 132 | 136 | 140 | 144 | 148 | 152 | 156 | *
* ------------------------------------------------- *
* | F18 | F19 | F20 | F21 | *
* ------------------------------------------------- *
* ------------------------------------------------- *
* | 160 | 164 | 168 | 172 | 176 | 180 | 184 | 188 | *
* ------------------------------------------------- *
* | F22 | F23 | F24 | F25 | *
* ------------------------------------------------- *
* ------------------------------------------------- *
* | 192 | 196 | 200 | 204 | 208 | 212 | 216 | 220 | *
* ------------------------------------------------- *
* | F26 | F27 | F28 | F29 | *
* ------------------------------------------------- *
* ------------------------|------------ *
* | 224 | 228 | 232 | 236 | 240 | 244 | *
* ------------------------|------------ *
* | F30 | F31 |bchai| LR | *
* ------------------------|------------ *
* *
*******************************************************/
.file "make_ppc32_sysv_elf_gas.S"
.text
.globl make_fcontext
.align 2
.type make_fcontext,@function
make_fcontext:
# save return address into R6
mflr %r6
# first arg of make_fcontext() == top address of context-function
# shift address in R3 to lower 16 byte boundary
clrrwi %r3, %r3, 4
# reserve space on context-stack, including 16 bytes of linkage
# and parameter area + 240 bytes of context-data (R1 % 16 == 0)
subi %r3, %r3, 16 + 240
# third arg of make_fcontext() == address of context-function
#ifdef __linux__
# save context-function as PC
stw %r5, 16(%r3)
#else
# save context-function for trampoline
stw %r5, 248(%r3)
#endif
# set back-chain to zero
li %r0, 0
stw %r0, 240(%r3)
# copy FPSCR to new context
mffs %f0
stfd %f0, 8(%r3)
#ifdef __linux__
# set hidden pointer for returning transfer_t
la %r0, 248(%r3)
stw %r0, 4(%r3)
#endif
# load address of label 1 into R4
bl 1f
1: mflr %r4
#ifndef __linux__
# compute abs address of trampoline, use as PC
addi %r7, %r4, trampoline - 1b
stw %r7, 16(%r3)
#endif
# compute abs address of label finish
addi %r4, %r4, finish - 1b
# save address of finish as return-address for context-function
# will be entered after context-function returns
stw %r4, 244(%r3)
# restore return address from R6
mtlr %r6
blr # return pointer to context-data
#ifndef __linux__
trampoline:
# On systems other than Linux, jump_fcontext is returning the
# transfer_t in R3:R4, but we need to pass transfer_t * R3 to
# our context-function.
lwz %r0, 8(%r1) # address of context-function
mtctr %r0
stw %r3, 8(%r1)
stw %r4, 12(%r1)
la %r3, 8(%r1) # address of transfer_t
bctr
#endif
finish:
# Use the secure PLT for _exit(0). If we use the insecure BSS PLT
# here, then the linker may use the insecure BSS PLT even if the
# C++ compiler wanted the secure PLT.
# set R30 for secure PLT, large model
bl 2f
2: mflr %r30
addis %r30, %r30, .Ltoc - 2b@ha
addi %r30, %r30, .Ltoc - 2b@l
# call _exit(0) with special addend 0x8000 for large model
li %r3, 0
bl _exit + 0x8000@plt
.size make_fcontext, .-make_fcontext
/* Provide the GOT pointer for secure PLT, large model. */
.section .got2,"aw"
.Ltoc = . + 0x8000
/* Mark that we don't need executable stack. */
.section .note.GNU-stack,"",%progbits
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