From 449b66753370d6b64bc9aa7e5c0592ba0fe6f680 Mon Sep 17 00:00:00 2001 From: johannst Date: Wed, 16 Sep 2020 22:23:09 +0000 Subject: deploy: 2e329ad934ef010fd94afe965f14ab895dcb515e --- arch/x86_64.html | 361 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 361 insertions(+) create mode 100644 arch/x86_64.html (limited to 'arch/x86_64.html') diff --git a/arch/x86_64.html b/arch/x86_64.html new file mode 100644 index 0000000..611c2ba --- /dev/null +++ b/arch/x86_64.html @@ -0,0 +1,361 @@ + + + + + + x86_64 - Notes + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
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x86_64

+

keywords: x86_64, x86, abi

+
    +
  • 64bit synonyms: x86_64, x64, amd64, intel 64
    • +
  • 32bit synonyms: x86, ia32, i386
    • +
  • ISA type: CISC
    • +
  • Endianness: little
    • +
+

Registers

+

General purpose register

+
bytes
+[7:0]      [3:0]   [1:0]   [1]   [0]     desc
+----------------------------------------------------------
+rax        eax     ax      ah    al      accumulator
+rbx        ebx     bx      bh    bl      base register
+rcx        ecx     cx      ch    cl      counter
+rdx        edx     dx      dh    dl      data register
+rsi        esi     si      -     sil     source index
+rdi        edi     di      -     dil     destination index
+rbp        ebp     bp      -     bpl     base pointer
+rsp        esp     sp      -     spl     stack pointer
+r8-15      rNd     rNw     -     rNb
+
+

Special register

+
bytes
+[7:0]      [3:0]     [1:0]      desc
+---------------------------------------------------
+rflags     eflags    flags      flags register
+rip        eip       ip         instruction pointer
+
+

FLAGS register

+
rflags
+bits  desc
+-----------------------------
+[11]  OF overflow flag
+[10]  DF direction flag
+ [7]  SF sign flag
+ [6]  ZF zero flag
+ [4]  AF auxiliary carry flag
+ [2]  PF parity flag
+ [0]  CF carry flag
+
+

Addressing

+
movw [rax], rbx         // save val in rbx at [rax]
+movw [imm], rbx         // save val in rbx at [imm]
+movw rax, [rbx+4*rcx]   // load val at [rbx+4*rcx] into rax
+
+

rip relative addressing:

+
lea rax, [rip+.my_str]       // load addr of .my_str into rax
+...
+.my_str:
+.asciz "Foo"
+
+

Size directives

+

Explicitly specify size of the operation.

+
mov  byte ptr [rax], 0xff    // save 1 byte(s) at [rax]
+mov  word ptr [rax], 0xff    // save 2 byte(s) at [rax]
+mov dword ptr [rax], 0xff    // save 4 byte(s) at [rax]
+mov qword ptr [rax], 0xff    // save 8 byte(s) at [rax]
+
+

SysV x86_64 ABI

+

Passing arguments to functions

+
    +
  • Integer/Pointer arguments +
    reg     arg
+-----------
+rdi       1
+rsi       2
+rdx       3
+rcx       4
+r8        5
+r9        6
+
    +
    • +
  • Floating point arguments +
    reg     arg
+-----------
+xmm0      1
+  ..     ..
+xmm7      7
+
    +
    • +
  • Additional arguments are passed on the stack. Arguments are pushed +right-to-left (RTL), meaning next arguments are closer to current rsp.
    • +
+

Return values from functions

+
    +
  • Integer/Pointer return values +
    reg          size
+-----------------
+rax        64 bit
+rax+rdx   128 bit
+
    +
    • +
  • Floating point return values: +
    reg            size
+-------------------
+xmm0         64 bit
+xmm0+xmm1   128 bit
+
    +
    • +
+

Caller saved registers

+

Caller must save these registers if they should be preserved across function +calls.

+
    +
  • rax
    • +
  • rcx
    • +
  • rdx
    • +
  • rsi
    • +
  • rdi
    • +
  • rsp
    • +
  • r8 - r11
    • +
+

Callee saved registers

+

Caller can expect these registers to be preserved across function calls. Callee +must must save these registers in case they are used.

+
    +
  • rbx
    • +
  • rbp
    • +
  • r12 – r15
    • +
+

Stack

+
    +
  • grows downwards
    • +
  • frames aligned on 16 byte boundary +
    HI ADDR
+ |                +------------+
+ |                | prev frame |
+ |                +------------+ <--- 16 byte aligned (X & ~0xf)
+ |       [rbp+8]  | saved RIP  |
+ |       [rbp]    | saved RBP  |
+ |       [rbp-8]  | func stack |
+ |                | ...        |
+ v                +------------+
+LO ADDR
+
    +
    • +
+

References

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