| /* |
| |
| x86 function call convention, 64-bit: |
| ------------------------------------- |
| arguments | callee-saved | extra caller-saved | return |
| [callee-clobbered] | | [callee-clobbered] | |
| --------------------------------------------------------------------------- |
| rdi rsi rdx rcx r8-9 | rbx rbp [*] r12-15 | r10-11 | rax, rdx [**] |
| |
| ( rsp is obviously invariant across normal function calls. (gcc can 'merge' |
| functions when it sees tail-call optimization possibilities) rflags is |
| clobbered. Leftover arguments are passed over the stack frame.) |
| |
| [*] In the frame-pointers case rbp is fixed to the stack frame. |
| |
| [**] for struct return values wider than 64 bits the return convention is a |
| bit more complex: up to 128 bits width we return small structures |
| straight in rax, rdx. For structures larger than that (3 words or |
| larger) the caller puts a pointer to an on-stack return struct |
| [allocated in the caller's stack frame] into the first argument - i.e. |
| into rdi. All other arguments shift up by one in this case. |
| Fortunately this case is rare in the kernel. |
| |
| For 32-bit we have the following conventions - kernel is built with |
| -mregparm=3 and -freg-struct-return: |
| |
| x86 function calling convention, 32-bit: |
| ---------------------------------------- |
| arguments | callee-saved | extra caller-saved | return |
| [callee-clobbered] | | [callee-clobbered] | |
| ------------------------------------------------------------------------- |
| eax edx ecx | ebx edi esi ebp [*] | <none> | eax, edx [**] |
| |
| ( here too esp is obviously invariant across normal function calls. eflags |
| is clobbered. Leftover arguments are passed over the stack frame. ) |
| |
| [*] In the frame-pointers case ebp is fixed to the stack frame. |
| |
| [**] We build with -freg-struct-return, which on 32-bit means similar |
| semantics as on 64-bit: edx can be used for a second return value |
| (i.e. covering integer and structure sizes up to 64 bits) - after that |
| it gets more complex and more expensive: 3-word or larger struct returns |
| get done in the caller's frame and the pointer to the return struct goes |
| into regparm0, i.e. eax - the other arguments shift up and the |
| function's register parameters degenerate to regparm=2 in essence. |
| |
| */ |
| |
| |
| /* |
| * 64-bit system call stack frame layout defines and helpers, |
| * for assembly code: |
| */ |
| |
| #define R15 0 |
| #define R14 8 |
| #define R13 16 |
| #define R12 24 |
| #define RBP 32 |
| #define RBX 40 |
| |
| /* arguments: interrupts/non tracing syscalls only save up to here: */ |
| #define R11 48 |
| #define R10 56 |
| #define R9 64 |
| #define R8 72 |
| #define RAX 80 |
| #define RCX 88 |
| #define RDX 96 |
| #define RSI 104 |
| #define RDI 112 |
| #define ORIG_RAX 120 /* + error_code */ |
| /* end of arguments */ |
| |
| /* cpu exception frame or undefined in case of fast syscall: */ |
| #define RIP 128 |
| #define CS 136 |
| #define EFLAGS 144 |
| #define RSP 152 |
| #define SS 160 |
| |
| #define ARGOFFSET R11 |
| #define SWFRAME ORIG_RAX |
| |
| .macro SAVE_ARGS addskip=0, norcx=0, nor891011=0 |
| subq $9*8+\addskip, %rsp |
| CFI_ADJUST_CFA_OFFSET 9*8+\addskip |
| movq %rdi, 8*8(%rsp) |
| CFI_REL_OFFSET rdi, 8*8 |
| movq %rsi, 7*8(%rsp) |
| CFI_REL_OFFSET rsi, 7*8 |
| movq %rdx, 6*8(%rsp) |
| CFI_REL_OFFSET rdx, 6*8 |
| .if \norcx |
| .else |
| movq %rcx, 5*8(%rsp) |
| CFI_REL_OFFSET rcx, 5*8 |
| .endif |
| movq %rax, 4*8(%rsp) |
| CFI_REL_OFFSET rax, 4*8 |
| .if \nor891011 |
| .else |
| movq %r8, 3*8(%rsp) |
| CFI_REL_OFFSET r8, 3*8 |
| movq %r9, 2*8(%rsp) |
| CFI_REL_OFFSET r9, 2*8 |
| movq %r10, 1*8(%rsp) |
| CFI_REL_OFFSET r10, 1*8 |
| movq %r11, (%rsp) |
| CFI_REL_OFFSET r11, 0*8 |
| .endif |
| .endm |
| |
| #define ARG_SKIP 9*8 |
| |
| .macro RESTORE_ARGS skiprax=0, addskip=0, skiprcx=0, skipr11=0, \ |
| skipr8910=0, skiprdx=0 |
| .if \skipr11 |
| .else |
| movq (%rsp), %r11 |
| CFI_RESTORE r11 |
| .endif |
| .if \skipr8910 |
| .else |
| movq 1*8(%rsp), %r10 |
| CFI_RESTORE r10 |
| movq 2*8(%rsp), %r9 |
| CFI_RESTORE r9 |
| movq 3*8(%rsp), %r8 |
| CFI_RESTORE r8 |
| .endif |
| .if \skiprax |
| .else |
| movq 4*8(%rsp), %rax |
| CFI_RESTORE rax |
| .endif |
| .if \skiprcx |
| .else |
| movq 5*8(%rsp), %rcx |
| CFI_RESTORE rcx |
| .endif |
| .if \skiprdx |
| .else |
| movq 6*8(%rsp), %rdx |
| CFI_RESTORE rdx |
| .endif |
| movq 7*8(%rsp), %rsi |
| CFI_RESTORE rsi |
| movq 8*8(%rsp), %rdi |
| CFI_RESTORE rdi |
| .if ARG_SKIP+\addskip > 0 |
| addq $ARG_SKIP+\addskip, %rsp |
| CFI_ADJUST_CFA_OFFSET -(ARG_SKIP+\addskip) |
| .endif |
| .endm |
| |
| .macro LOAD_ARGS offset, skiprax=0 |
| movq \offset(%rsp), %r11 |
| movq \offset+8(%rsp), %r10 |
| movq \offset+16(%rsp), %r9 |
| movq \offset+24(%rsp), %r8 |
| movq \offset+40(%rsp), %rcx |
| movq \offset+48(%rsp), %rdx |
| movq \offset+56(%rsp), %rsi |
| movq \offset+64(%rsp), %rdi |
| .if \skiprax |
| .else |
| movq \offset+72(%rsp), %rax |
| .endif |
| .endm |
| |
| #define REST_SKIP 6*8 |
| |
| .macro SAVE_REST |
| subq $REST_SKIP, %rsp |
| CFI_ADJUST_CFA_OFFSET REST_SKIP |
| movq %rbx, 5*8(%rsp) |
| CFI_REL_OFFSET rbx, 5*8 |
| movq %rbp, 4*8(%rsp) |
| CFI_REL_OFFSET rbp, 4*8 |
| movq %r12, 3*8(%rsp) |
| CFI_REL_OFFSET r12, 3*8 |
| movq %r13, 2*8(%rsp) |
| CFI_REL_OFFSET r13, 2*8 |
| movq %r14, 1*8(%rsp) |
| CFI_REL_OFFSET r14, 1*8 |
| movq %r15, (%rsp) |
| CFI_REL_OFFSET r15, 0*8 |
| .endm |
| |
| .macro RESTORE_REST |
| movq (%rsp), %r15 |
| CFI_RESTORE r15 |
| movq 1*8(%rsp), %r14 |
| CFI_RESTORE r14 |
| movq 2*8(%rsp), %r13 |
| CFI_RESTORE r13 |
| movq 3*8(%rsp), %r12 |
| CFI_RESTORE r12 |
| movq 4*8(%rsp), %rbp |
| CFI_RESTORE rbp |
| movq 5*8(%rsp), %rbx |
| CFI_RESTORE rbx |
| addq $REST_SKIP, %rsp |
| CFI_ADJUST_CFA_OFFSET -(REST_SKIP) |
| .endm |
| |
| .macro SAVE_ALL |
| SAVE_ARGS |
| SAVE_REST |
| .endm |
| |
| .macro RESTORE_ALL addskip=0 |
| RESTORE_REST |
| RESTORE_ARGS 0, \addskip |
| .endm |
| |
| .macro icebp |
| .byte 0xf1 |
| .endm |