diff options
Diffstat (limited to 'arch/x86/include/asm/calling.h')
| -rw-r--r-- | arch/x86/include/asm/calling.h | 240 |
1 files changed, 157 insertions, 83 deletions
diff --git a/arch/x86/include/asm/calling.h b/arch/x86/include/asm/calling.h index 2bc162e0ec6..cb4c73bfeb4 100644 --- a/arch/x86/include/asm/calling.h +++ b/arch/x86/include/asm/calling.h @@ -1,5 +1,58 @@ /* - * Some macros to handle stack frames in assembly. + + 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 <asm/dwarf2.h> + +#ifdef CONFIG_X86_64 + +/* + * 64-bit system call stack frame layout defines and helpers, + * for assembly code: */ #define R15 0 @@ -9,7 +62,7 @@ #define RBP 32 #define RBX 40 -/* arguments: interrupts/non tracing syscalls only save upto here*/ +/* arguments: interrupts/non tracing syscalls only save up to here: */ #define R11 48 #define R10 56 #define R9 64 @@ -22,7 +75,7 @@ #define ORIG_RAX 120 /* + error_code */ /* end of arguments */ -/* cpu exception frame or undefined in case of fast syscall. */ +/* cpu exception frame or undefined in case of fast syscall: */ #define RIP 128 #define CS 136 #define EFLAGS 144 @@ -32,72 +85,57 @@ #define ARGOFFSET R11 #define SWFRAME ORIG_RAX - .macro SAVE_ARGS addskip=0, norcx=0, nor891011=0 + .macro SAVE_ARGS addskip=0, save_rcx=1, save_r891011=1 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 + 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 %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 + + 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 +#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 + .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 \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 + + .if \rstor_r8910 + movq_cfi_restore 1*8, r10 + movq_cfi_restore 2*8, r9 + movq_cfi_restore 3*8, r8 .endif - .if \skiprax - .else - movq 4*8(%rsp), %rax - CFI_RESTORE rax + + .if \rstor_rax + movq_cfi_restore 4*8, rax .endif - .if \skiprcx - .else - movq 5*8(%rsp), %rcx - CFI_RESTORE rcx + + .if \rstor_rcx + movq_cfi_restore 5*8, rcx .endif - .if \skiprdx - .else - movq 6*8(%rsp), %rdx - CFI_RESTORE rdx + + .if \rstor_rdx + movq_cfi_restore 6*8, rdx .endif - movq 7*8(%rsp), %rsi - CFI_RESTORE rsi - movq 8*8(%rsp), %rdi - CFI_RESTORE rdi + + 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) @@ -119,38 +157,26 @@ .endif .endm -#define REST_SKIP 6*8 +#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 + 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 (%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 + 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 @@ -162,9 +188,57 @@ .macro RESTORE_ALL addskip=0 RESTORE_REST - RESTORE_ARGS 0, \addskip + RESTORE_ARGS 1, \addskip .endm .macro icebp .byte 0xf1 .endm + +#else /* CONFIG_X86_64 */ + +/* + * For 32bit only simplified versions of SAVE_ALL/RESTORE_ALL. These + * are different from the entry_32.S versions in not changing the segment + * registers. So only suitable for in kernel use, not when transitioning + * from or to user space. The resulting stack frame is not a standard + * pt_regs frame. The main use case is calling C code from assembler + * when all the registers need to be preserved. + */ + + .macro SAVE_ALL + pushl_cfi %eax + CFI_REL_OFFSET eax, 0 + pushl_cfi %ebp + CFI_REL_OFFSET ebp, 0 + pushl_cfi %edi + CFI_REL_OFFSET edi, 0 + pushl_cfi %esi + CFI_REL_OFFSET esi, 0 + pushl_cfi %edx + CFI_REL_OFFSET edx, 0 + pushl_cfi %ecx + CFI_REL_OFFSET ecx, 0 + pushl_cfi %ebx + CFI_REL_OFFSET ebx, 0 + .endm + + .macro RESTORE_ALL + popl_cfi %ebx + CFI_RESTORE ebx + popl_cfi %ecx + CFI_RESTORE ecx + popl_cfi %edx + CFI_RESTORE edx + popl_cfi %esi + CFI_RESTORE esi + popl_cfi %edi + CFI_RESTORE edi + popl_cfi %ebp + CFI_RESTORE ebp + popl_cfi %eax + CFI_RESTORE eax + .endm + +#endif /* CONFIG_X86_64 */ + |