0x7fffffffdb58: 0x004005ba 0x00000000 0x00000000 0x00000000 <-----funcb的栈帧 [0x7fffffffdb60, 0x7fffffffdb80]，其中a=0x1a，其中这个栈的栈底是返回地址4005d
0x7fffffffdb68: 0x00000000 0x0000001a 0x00000000 0x00000000 0x4005d8，是函数funca的返回地址，然后往上就逐渐是各种局部变量
0x7fffffffdb78: 0x004005d8 0x00000000 0x00400470 0x00000000
0x7fffffffdb88: 0xffffdd90 0x00000019 0x00000000 0x00000000 <-----funca的栈帧，这个栈帧[0x7fffffffdb80, 0x7fffffffdba0], 其中a=0x19
0x7fffffffdb98: 0x0040060d 0x00000000 0x00000000 0x00000000 <----add的栈帧stack frame [0x7fffffffdba0,0x7ffffffdbd0],其中a=0x18，b=0x27
0x7fffffffdba8: 0x00000028 0x00000018 0x00000001 0x00000000
0x7fffffffdbb8: 0x00000040 0x00000000 0x6562b026 0x00000000
0x7fffffffdbc8: 0x0040069f 0x00000000 0xffffdd60 0x00007fff
0x7fffffffdbd8: 0xf7dee923 0x00000002 0x00000000 0x00000017
0x7fffffffdbe8: 0x00000027 0x00000000 0x00000000 0x00000000
0x7fffffffdbf8: 0x00000003 0x00000000 0xffffdda8 0x00007fff
0x7fffffffdc08: 0x00000000 0x00000000 0x00400750 0x00000000
0x7fffffffdc18: 0xf7de7ab0 0x00007fff 0x000000ff 0x00000000
0x7fffffffdc28: 0xff000000 0x00000000 0x00000000 0x00000000
0x7fffffffdc38: 0x00000000 0x00000000 0x00000000 0x00000000
所以说一个栈的栈帧，最开始是上一个函数的返回地址，以及本函数的堆栈
gdb中显示出来的栈帧的信息中，“Stack frame at 0x7fffffffdb80” 都是指栈帧的基地址。
(gdb) info frame 1
Stack frame at 0x7fffffffdb80:
rip = 0x4005ba in funcb (sleep.c:15); saved rip = 0x4005d8
called by frame at 0x7fffffffdba0, caller of frame at 0x7fffffffdb60
source language c.
Arglist at 0x7fffffffdb58, args: a=26
Locals at 0x7fffffffdb58, Previous frame's sp is 0x7fffffffdb80
Saved registers:
rip at 0x7fffffffdb78
(gdb) info frame 2
Stack frame at 0x7fffffffdba0:
rip = 0x4005d8 in funca (sleep.c:19); saved rip = 0x40060d
called by frame at 0x7fffffffdbd0, caller of frame at 0x7fffffffdb80
source language c.
Arglist at 0x7fffffffdb78, args: a=25
Locals at 0x7fffffffdb78, Previous frame's sp is 0x7fffffffdba0
Saved registers:
rip at 0x7fffffffdb98
(gdb) info frame 3
Stack frame at 0x7fffffffdbd0:
rip = 0x40060d in add (sleep.c:27); saved rip = 0x40069f
called by frame at 0x7fffffffdcb0, caller of frame at 0x7fffffffdba0
source language c.
Arglist at 0x7fffffffdb98, args: a=24, b=40
Locals at 0x7fffffffdb98, Previous frame's sp is 0x7fffffffdbd0
Saved registers:
rip at 0x7fffffffdbc8
(gdb) info frame 4
Stack frame at 0x7fffffffdcb0:
rip = 0x40069f in print (sleep.c:35); saved rip = 0x4006c7
called by frame at 0x7fffffffdcc0, caller of frame at 0x7fffffffdbd0
source language c.
Arglist at 0x7fffffffdbc8, args: i=2
Locals at 0x7fffffffdbc8, Previous frame's sp is 0x7fffffffdcb0
Saved registers:
rip at 0x7fffffffdca8
以函数funca->funcb来看一一下函数的调用过程
00000000004005a2 <funcb>:
4005a2: 48 83 ec 18 sub $0x18,%rsp rsp这个时候的值就确定了
4005a6: 89 7c 24 0c mov %edi,0xc(%rsp）
4005aa: 83 44 24 0c 01 addl $0x1,0xc(%rsp)
4005af: 8b 44 24 0c mov 0xc(%rsp),%eax
4005b3: 89 c7 mov %eax,%edi
4005b5: e8 ac ff ff ff callq 400566 <funcc>
4005ba: 90 nop
4005bb: 48 83 c4 18 add $0x18,%rsp
4005bf: c3 retq 00000000004005c0 <funca>:
4005c0: 48 83 ec 18 sub $0x18,%rsp
4005c4: 89 7c 24 0c mov %edi,0xc(%rsp)
4005c8: 83 44 24 0c 01 addl $0x1,0xc(%rsp)
4005cd: 8b 44 24 0c mov 0xc(%rsp),%eax
4005d1: 89 c7 mov %eax,%edi
4005d3: e8 ca ff ff ff callq 4005a2 <funcb> callq是push ip；rsp++
4005d8: 90 nop
4005d9: 48 83 c4 18 add $0x18,%rsp
4005dd: c3 retq
dwarf当中存储的信息是啥样子的呢？
< 1><0x000000ca> DW_TAG_subprogram
DW_AT_external yes(1)
DW_AT_name "funcb"
DW_AT_decl_file 0x00000001 /home/hon/codebox/gcc/sleep.c
DW_AT_decl_line 0x0000000d
DW_AT_prototyped yes(1)
DW_AT_type <0x00000049>
DW_AT_low_pc 0x004005a2
DW_AT_high_pc <offset-from-lowpc>30
DW_AT_frame_base len 0x0001: 9c: DW_OP_call_frame_cfa
DW_AT_GNU_all_tail_call_sitesyes(1)
DW_AT_sibling <0x000000f8>
< 2><0x000000eb> DW_TAG_formal_parameter
DW_AT_name "a"
DW_AT_decl_file 0x00000001 /home/hon/codebox/gcc/sleep.c
DW_AT_decl_line 0x0000000d
DW_AT_type <0x00000049>
DW_AT_location len 0x0002: 916c: DW_OP_fbreg -20
funca中的信息是啥样子的？
< 1><0x000000f8> DW_TAG_subprogram
DW_AT_external yes(1)
DW_AT_name "funca"
DW_AT_decl_file 0x00000001 /home/hon/codebox/gcc/sleep.c
DW_AT_decl_line 0x00000011
DW_AT_prototyped yes(1)
DW_AT_type <0x00000049>
DW_AT_low_pc 0x004005c0
DW_AT_high_pc <offset-from-lowpc>30
DW_AT_frame_base len 0x0001: 9c: DW_OP_call_frame_cfa
DW_AT_GNU_all_tail_call_sitesyes(1)
DW_AT_sibling <0x00000126>
< 2><0x00000119> DW_TAG_formal_parameter
DW_AT_name "a"
DW_AT_decl_file 0x00000001 /home/hon/codebox/gcc/sleep.c
DW_AT_decl_line 0x00000011
DW_AT_type <0x00000049>
DW_AT_location len 0x0002: 916c: DW_OP_fbreg -20