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add ARM buildin setjmp/longjmp support #3

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merged 2 commits into from
Sep 3, 2016
Merged

add ARM buildin setjmp/longjmp support #3

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2af20a7
add ARMv7 support
Sep 3, 2016
f627803
add ARM buildin setjmp/longjmp support
Sep 3, 2016
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33 changes: 33 additions & 0 deletions md.S
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Original file line number Diff line number Diff line change
Expand Up @@ -462,6 +462,39 @@
#elif defined(__arm__)

/* TODO: FIXME: implement setjmp and longjmp for ARM */
.globl _st_md_cxt_save
.type _st_md_cxt_save, %function
.align 2
_st_md_cxt_save:
mov ip, r0 // r0为参数jmpbuf地址
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// r0 is the param jmpbuf ptr address.

// 以下指令等同于
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Save registers like:

// *ip++ = v1
// *ip++ = ...
// *ip++ = v6
// *ip++ = sl
// *ip++ = fp
stmia ip!, {v1-v6, sl, fp} // TODO:根据不同的ARM版本,这里要做不同的寄存器保存
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// TODO: compatible with other ARM version.

movs r2, sp
stmia ip!, {r2, lr}
mov r0, #0 // setjmp first return 0(r0存放返回值)
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// r0 save the return value(0) of setjmp.

bx lr // return
.size _st_md_cxt_save, .-_st_md_cxt_save

.globl _st_md_cxt_restore
.type _st_md_cxt_restore, %function
.align 2
_st_md_cxt_restore:
mov ip, r0 // r0 -> jmp_buf
movs r0, r1 // r1 -> return value
// 下面两条指令是一组,也就是if(r0 == 0) r0 = 1
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@winlinvip winlinvip Sep 3, 2016 •
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// The bellow is a group, that is:
// if (r0 == 0) r0 =1;

ITT eq
moveq r0, #1 // 从long_jmp返回一定不能是0
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// long_jmp should never return 0


ldmia ip!, {v1-v6, sl, fp} // 恢复寄存器
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// restore registers.

ldr sp, [ip], #4 // ip会+4, 这条指令相当于sp = *ip; ip+=4;
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// restore sp, like: sp=*ip; ip+=4;

ldr lr, [ip], #4
bx lr
.size _st_md_cxt_restore, .-_st_md_cxt_restore

#endif

12 changes: 6 additions & 6 deletions md.h
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Original file line number Diff line number Diff line change
Expand Up @@ -421,12 +421,12 @@
#elif defined(__arm__)
#define MD_STACK_GROWS_DOWN

#if defined(__GLIBC__) && __GLIBC__ >= 2
/* Merge from https://github.com/michaeltalyansky/state-threads/commit/56554a5c425aee8e7a73782eae23d74d83c4120a */
#define MD_GET_SP(_t) (_t)->context[0].__jmpbuf[8]
#else
#error "ARM/Linux pre-glibc2 not supported yet"
#endif /* defined(__GLIBC__) && __GLIBC__ >= 2 */
#define MD_USE_BUILTIN_SETJMP

#ifndef JB_RSP
#define JB_RSP 8 // 这里的JB_RSP的具体数值要跟md.S里面的保存位置对应
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这个按照ST的惯例，我觉得还是不要改了，就魔法数吧，没有关系的。
只保留宏定义：MD_USE_BUILTIN_SETJMP

#endif
#define MD_GET_SP(_t) (_t)->context[0].__jmpbuf[JB_RSP]

#elif defined(__s390__)
#define MD_STACK_GROWS_DOWN
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