当我反汇编处理浮点值的 ARM 代码时，如何打印出寄存器？（我正在使用 Gdb）。
0x000083d8 <+12>: ldr r3, [pc, #56] ; 0x8418 <main+76>
0x000083dc <+16>: str r3, [r11, #-8]
0x000083e0 <+20>: vldr s14, [r11, #-8]
0x000083e4 <+24>: vldr s15, [pc, #40] ; 0x8414 <main+72>
s14在这种情况下，我如何打印出登记册？
要打印s14来自 gdb的值：
info registers s14
p $reg
在从源用户模式+ GDB 8.2 Ubuntu 16.04构建的 QEMU v3.0.0 中，如果您这样做：info registers并且info vector它不显示浮点值而是将它们四舍五入为整数，我认为存在错误。
但是，以下确实有效。首先我加载：
1.5, 2.5, 3.5, 4.5
进入 v0/q0。
ARMv8
(gdb) p $v0
$2 = {
d = {
f = {[0] = 8.0000018998980522, [1] = 1024.0002455711365},
u = {[0] = 4620693218751676416, [1] = 4652218416153755648},
s = {[0] = 4620693218751676416, [1] = 4652218416153755648}
},
s = {
f = {[0] = 1.5, [1] = 2.5, [2] = 3.5, [3] = 4.5},
u = {[0] = 1069547520, [1] = 1075838976, [2] = 1080033280, [3] = 1083179008},
s = {[0] = 1069547520, [1] = 1075838976, [2] = 1080033280, [3] = 1083179008}
},
h = {
u = {[0] = 0, [1] = 16320, [2] = 0, [3] = 16416, [4] = 0, [5] = 16480, [6] = 0, [7] = 16528},
s = {[0] = 0, [1] = 16320, [2] = 0, [3] = 16416, [4] = 0, [5] = 16480, [6] = 0, [7] = 16528}
},
b = {
u = {[0] = 0, [1] = 0, [2] = 192, [3] = 63, [4] = 0, [5] = 0, [6] = 32, [7] = 64, [8] = 0, [9] = 0, [10] = 96, [11] = 64, [12] = 0, [13] = 0, [14] = 144, [15] = 64},
s = {[0] = 0, [1] = 0, [2] = -64, [3] = 63, [4] = 0, [5] = 0, [6] = 32, [7] = 64, [8] = 0, [9] = 0, [10] = 96, [11] = 64, [12] = 0, [13] = 0, [14] = -112, [15] = 64}
},
q = {
u = {[0] = 85818282497786728556221825347259203584},
s = {[0] = 85818282497786728556221825347259203584}
}
}
和：
(gdb) p $v0.s
$3 = {
f = {[0] = 1.5, [1] = 2.5, [2] = 3.5, [3] = 4.5},
u = {[0] = 1069547520, [1] = 1075838976, [2] = 1080033280, [3] = 1083179008},
s = {[0] = 1069547520, [1] = 1075838976, [2] = 1080033280, [3] = 1083179008}
}
和：
(gdb) p $v0.s.f
$3 = {[0] = 1.5, [1] = 2.5, [2] = 3.5, [3] = 4.5}
测试设置。
ARMv7
(gdb) p $q0
$3 = {
u8 = {[0] = 0, [1] = 0, [2] = 192, [3] = 63, [4] = 0, [5] = 0, [6] = 32, [7] = 64, [8] = 0, [9] = 0, [10] = 96, [11] = 64, [12] = 0, [13] = 0, [14] = 144, [15] = 64},
u16 = {[0] = 0, [1] = 16320, [2] = 0, [3] = 16416, [4] = 0, [5] = 16480, [6] = 0, [7] = 16528},
u32 = {[0] = 1069547520, [1] = 1075838976, [2] = 1080033280, [3] = 1083179008},
u64 = {[0] = 4620693218751676416, [1] = 4652218416153755648},
f32 = {[0] = 1.5, [1] = 2.5, [2] = 3.5, [3] = 4.5},
f64 = {[0] = 8.0000018998980522, [1] = 1024.0002455711365}
}
和：
(gdb) p $q0.f32
$5 = {[0] = 1.5, [1] = 2.5, [2] = 3.5, [3] = 4.5}
测试设置。
漏洞
我之前提到的错误在 ARMv8 中导致：
(gdb) i r v0
v0 {
d = {
f = {[0x0] = 0x8, [0x1] = 0x400},
u = {[0x0] = 0x402000003fc00000, [0x1] = 0x4090000040600000},
s = {[0x0] = 0x402000003fc00000, [0x1] = 0x4090000040600000}
},
s = {
f = {[0x0] = 0x1, [0x1] = 0x2, [0x2] = 0x3, [0x3] = 0x4},
u = {[0x0] = 0x3fc00000, [0x1] = 0x40200000, [0x2] = 0x40600000, [0x3] = 0x40900000},
s = {[0x0] = 0x3fc00000, [0x1] = 0x40200000, [0x2] = 0x40600000, [0x3] = 0x40900000}
},
h = {
u = {[0x0] = 0x0, [0x1] = 0x3fc0, [0x2] = 0x0, [0x3] = 0x4020, [0x4] = 0x0, [0x5] = 0x4060, [0x6] = 0x0, [0x7] = 0x4090},
s = {[0x0] = 0x0, [0x1] = 0x3fc0, [0x2] = 0x0, [0x3] = 0x4020, [0x4] = 0x0, [0x5] = 0x4060, [0x6] = 0x0, [0x7] = 0x4090}
},
b = {
u = {[0x0] = 0x0, [0x1] = 0x0, [0x2] = 0xc0, [0x3] = 0x3f, [0x4] = 0x0, [0x5] = 0x0, [0x6] = 0x20, [0x7] = 0x40, [0x8] = 0x0, [0x9] = 0x0, [0xa] = 0x60, [0xb] = 0x40, [0xc] = 0x0, [0xd] = 0x0, [0xe] = 0x90, [0xf] = 0x40},
s = {[0x0] = 0x0, [0x1] = 0x0, [0x2] = 0xc0, [0x3] = 0x3f, [0x4] = 0x0, [0x5] = 0x0, [0x6] = 0x20, [0x7] = 0x40, [0x8] = 0x0, [0x9] = 0x0, [0xa] = 0x60, [0xb] = 0x40, [0xc] = 0x0, [0xd] = 0x0, [0xe] = 0x90, [0xf] = 0x40}
},
q = {
u = {[0x0] = 0x4090000040600000402000003fc00000},
s = {[0x0] = 0x4090000040600000402000003fc00000}
}
}
所以请注意该v0.s.f行如何舍入整数而不是浮点数：
s = {
f = {[0x0] = 0x1, [0x1] = 0x2, [0x2] = 0x3, [0x3] = 0x4},
SVE
尚未在 QEMU 上实现，请参阅：https : //stackoverflow.com/questions/52888916/how-to-assemble-arm-sve-instructions-with-gnu-gas-or-llvm-and-run-it-on- qemu/52888917#52888917