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Diffstat (limited to 'arch/x86/include/asm/calling.h')
| -rw-r--r-- | arch/x86/include/asm/calling.h | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/arch/x86/include/asm/calling.h b/arch/x86/include/asm/calling.h new file mode 100644 index 00000000..a9e3a740 --- /dev/null +++ b/arch/x86/include/asm/calling.h @@ -0,0 +1,196 @@ +/* + + 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. + +*/ + +#include "dwarf2.h" + +/* + * 64-bit system call stack frame layout defines and helpers, for + * assembly code (note that the seemingly unnecessary parentheses + * are to prevent cpp from inserting spaces in expressions that get + * passed to macros): + */ + +#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, save_rcx=1, save_r891011=1 + subq $9*8+\addskip, %rsp + CFI_ADJUST_CFA_OFFSET 9*8+\addskip + movq_cfi rdi, 8*8 + movq_cfi rsi, 7*8 + movq_cfi rdx, 6*8 + + .if \save_rcx + movq_cfi rcx, 5*8 + .endif + + movq_cfi rax, 4*8 + + .if \save_r891011 + movq_cfi r8, 3*8 + movq_cfi r9, 2*8 + movq_cfi r10, 1*8 + movq_cfi r11, 0*8 + .endif + + .endm + +#define ARG_SKIP (9*8) + + .macro RESTORE_ARGS rstor_rax=1, addskip=0, rstor_rcx=1, rstor_r11=1, \ + rstor_r8910=1, rstor_rdx=1 + .if \rstor_r11 + movq_cfi_restore 0*8, r11 + .endif + + .if \rstor_r8910 + movq_cfi_restore 1*8, r10 + movq_cfi_restore 2*8, r9 + movq_cfi_restore 3*8, r8 + .endif + + .if \rstor_rax + movq_cfi_restore 4*8, rax + .endif + + .if \rstor_rcx + movq_cfi_restore 5*8, rcx + .endif + + .if \rstor_rdx + movq_cfi_restore 6*8, rdx + .endif + + movq_cfi_restore 7*8, rsi + movq_cfi_restore 8*8, 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_cfi rbx, 5*8 + movq_cfi rbp, 4*8 + movq_cfi r12, 3*8 + movq_cfi r13, 2*8 + movq_cfi r14, 1*8 + movq_cfi r15, 0*8 + .endm + + .macro RESTORE_REST + movq_cfi_restore 0*8, r15 + movq_cfi_restore 1*8, r14 + movq_cfi_restore 2*8, r13 + movq_cfi_restore 3*8, r12 + movq_cfi_restore 4*8, rbp + movq_cfi_restore 5*8, 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 1, \addskip + .endm + + .macro icebp + .byte 0xf1 + .endm |