1d36f9479SIngo Molnar /* 2d36f9479SIngo Molnar 3d36f9479SIngo Molnar x86 function call convention, 64-bit: 4d36f9479SIngo Molnar ------------------------------------- 5d36f9479SIngo Molnar arguments | callee-saved | extra caller-saved | return 6d36f9479SIngo Molnar [callee-clobbered] | | [callee-clobbered] | 7d36f9479SIngo Molnar --------------------------------------------------------------------------- 8d36f9479SIngo Molnar rdi rsi rdx rcx r8-9 | rbx rbp [*] r12-15 | r10-11 | rax, rdx [**] 9d36f9479SIngo Molnar 10d36f9479SIngo Molnar ( rsp is obviously invariant across normal function calls. (gcc can 'merge' 11d36f9479SIngo Molnar functions when it sees tail-call optimization possibilities) rflags is 12d36f9479SIngo Molnar clobbered. Leftover arguments are passed over the stack frame.) 13d36f9479SIngo Molnar 14d36f9479SIngo Molnar [*] In the frame-pointers case rbp is fixed to the stack frame. 15d36f9479SIngo Molnar 16d36f9479SIngo Molnar [**] for struct return values wider than 64 bits the return convention is a 17d36f9479SIngo Molnar bit more complex: up to 128 bits width we return small structures 18d36f9479SIngo Molnar straight in rax, rdx. For structures larger than that (3 words or 19d36f9479SIngo Molnar larger) the caller puts a pointer to an on-stack return struct 20d36f9479SIngo Molnar [allocated in the caller's stack frame] into the first argument - i.e. 21d36f9479SIngo Molnar into rdi. All other arguments shift up by one in this case. 22d36f9479SIngo Molnar Fortunately this case is rare in the kernel. 23d36f9479SIngo Molnar 24d36f9479SIngo Molnar For 32-bit we have the following conventions - kernel is built with 25d36f9479SIngo Molnar -mregparm=3 and -freg-struct-return: 26d36f9479SIngo Molnar 27d36f9479SIngo Molnar x86 function calling convention, 32-bit: 28d36f9479SIngo Molnar ---------------------------------------- 29d36f9479SIngo Molnar arguments | callee-saved | extra caller-saved | return 30d36f9479SIngo Molnar [callee-clobbered] | | [callee-clobbered] | 31d36f9479SIngo Molnar ------------------------------------------------------------------------- 32d36f9479SIngo Molnar eax edx ecx | ebx edi esi ebp [*] | <none> | eax, edx [**] 33d36f9479SIngo Molnar 34d36f9479SIngo Molnar ( here too esp is obviously invariant across normal function calls. eflags 35d36f9479SIngo Molnar is clobbered. Leftover arguments are passed over the stack frame. ) 36d36f9479SIngo Molnar 37d36f9479SIngo Molnar [*] In the frame-pointers case ebp is fixed to the stack frame. 38d36f9479SIngo Molnar 39d36f9479SIngo Molnar [**] We build with -freg-struct-return, which on 32-bit means similar 40d36f9479SIngo Molnar semantics as on 64-bit: edx can be used for a second return value 41d36f9479SIngo Molnar (i.e. covering integer and structure sizes up to 64 bits) - after that 42d36f9479SIngo Molnar it gets more complex and more expensive: 3-word or larger struct returns 43d36f9479SIngo Molnar get done in the caller's frame and the pointer to the return struct goes 44d36f9479SIngo Molnar into regparm0, i.e. eax - the other arguments shift up and the 45d36f9479SIngo Molnar function's register parameters degenerate to regparm=2 in essence. 46d36f9479SIngo Molnar 47d36f9479SIngo Molnar */ 48d36f9479SIngo Molnar 49d36f9479SIngo Molnar #ifdef CONFIG_X86_64 50d36f9479SIngo Molnar 51d36f9479SIngo Molnar /* 52d36f9479SIngo Molnar * 64-bit system call stack frame layout defines and helpers, 53d36f9479SIngo Molnar * for assembly code: 54d36f9479SIngo Molnar */ 55d36f9479SIngo Molnar 56d36f9479SIngo Molnar /* The layout forms the "struct pt_regs" on the stack: */ 57d36f9479SIngo Molnar /* 58d36f9479SIngo Molnar * C ABI says these regs are callee-preserved. They aren't saved on kernel entry 59d36f9479SIngo Molnar * unless syscall needs a complete, fully filled "struct pt_regs". 60d36f9479SIngo Molnar */ 61d36f9479SIngo Molnar #define R15 0*8 62d36f9479SIngo Molnar #define R14 1*8 63d36f9479SIngo Molnar #define R13 2*8 64d36f9479SIngo Molnar #define R12 3*8 65d36f9479SIngo Molnar #define RBP 4*8 66d36f9479SIngo Molnar #define RBX 5*8 67d36f9479SIngo Molnar /* These regs are callee-clobbered. Always saved on kernel entry. */ 68d36f9479SIngo Molnar #define R11 6*8 69d36f9479SIngo Molnar #define R10 7*8 70d36f9479SIngo Molnar #define R9 8*8 71d36f9479SIngo Molnar #define R8 9*8 72d36f9479SIngo Molnar #define RAX 10*8 73d36f9479SIngo Molnar #define RCX 11*8 74d36f9479SIngo Molnar #define RDX 12*8 75d36f9479SIngo Molnar #define RSI 13*8 76d36f9479SIngo Molnar #define RDI 14*8 77d36f9479SIngo Molnar /* 78d36f9479SIngo Molnar * On syscall entry, this is syscall#. On CPU exception, this is error code. 79d36f9479SIngo Molnar * On hw interrupt, it's IRQ number: 80d36f9479SIngo Molnar */ 81d36f9479SIngo Molnar #define ORIG_RAX 15*8 82d36f9479SIngo Molnar /* Return frame for iretq */ 83d36f9479SIngo Molnar #define RIP 16*8 84d36f9479SIngo Molnar #define CS 17*8 85d36f9479SIngo Molnar #define EFLAGS 18*8 86d36f9479SIngo Molnar #define RSP 19*8 87d36f9479SIngo Molnar #define SS 20*8 88d36f9479SIngo Molnar 89d36f9479SIngo Molnar #define SIZEOF_PTREGS 21*8 90d36f9479SIngo Molnar 91d36f9479SIngo Molnar .macro ALLOC_PT_GPREGS_ON_STACK addskip=0 92d36f9479SIngo Molnar addq $-(15*8+\addskip), %rsp 93d36f9479SIngo Molnar .endm 94d36f9479SIngo Molnar 95d36f9479SIngo Molnar .macro SAVE_C_REGS_HELPER offset=0 rax=1 rcx=1 r8910=1 r11=1 96d36f9479SIngo Molnar .if \r11 97d36f9479SIngo Molnar movq %r11, 6*8+\offset(%rsp) 98d36f9479SIngo Molnar .endif 99d36f9479SIngo Molnar .if \r8910 100d36f9479SIngo Molnar movq %r10, 7*8+\offset(%rsp) 101d36f9479SIngo Molnar movq %r9, 8*8+\offset(%rsp) 102d36f9479SIngo Molnar movq %r8, 9*8+\offset(%rsp) 103d36f9479SIngo Molnar .endif 104d36f9479SIngo Molnar .if \rax 105d36f9479SIngo Molnar movq %rax, 10*8+\offset(%rsp) 106d36f9479SIngo Molnar .endif 107d36f9479SIngo Molnar .if \rcx 108d36f9479SIngo Molnar movq %rcx, 11*8+\offset(%rsp) 109d36f9479SIngo Molnar .endif 110d36f9479SIngo Molnar movq %rdx, 12*8+\offset(%rsp) 111d36f9479SIngo Molnar movq %rsi, 13*8+\offset(%rsp) 112d36f9479SIngo Molnar movq %rdi, 14*8+\offset(%rsp) 113d36f9479SIngo Molnar .endm 114d36f9479SIngo Molnar .macro SAVE_C_REGS offset=0 115d36f9479SIngo Molnar SAVE_C_REGS_HELPER \offset, 1, 1, 1, 1 116d36f9479SIngo Molnar .endm 117d36f9479SIngo Molnar .macro SAVE_C_REGS_EXCEPT_RAX_RCX offset=0 118d36f9479SIngo Molnar SAVE_C_REGS_HELPER \offset, 0, 0, 1, 1 119d36f9479SIngo Molnar .endm 120d36f9479SIngo Molnar .macro SAVE_C_REGS_EXCEPT_R891011 121d36f9479SIngo Molnar SAVE_C_REGS_HELPER 0, 1, 1, 0, 0 122d36f9479SIngo Molnar .endm 123d36f9479SIngo Molnar .macro SAVE_C_REGS_EXCEPT_RCX_R891011 124d36f9479SIngo Molnar SAVE_C_REGS_HELPER 0, 1, 0, 0, 0 125d36f9479SIngo Molnar .endm 126d36f9479SIngo Molnar .macro SAVE_C_REGS_EXCEPT_RAX_RCX_R11 127d36f9479SIngo Molnar SAVE_C_REGS_HELPER 0, 0, 0, 1, 0 128d36f9479SIngo Molnar .endm 129d36f9479SIngo Molnar 130d36f9479SIngo Molnar .macro SAVE_EXTRA_REGS offset=0 131d36f9479SIngo Molnar movq %r15, 0*8+\offset(%rsp) 132d36f9479SIngo Molnar movq %r14, 1*8+\offset(%rsp) 133d36f9479SIngo Molnar movq %r13, 2*8+\offset(%rsp) 134d36f9479SIngo Molnar movq %r12, 3*8+\offset(%rsp) 135d36f9479SIngo Molnar movq %rbp, 4*8+\offset(%rsp) 136d36f9479SIngo Molnar movq %rbx, 5*8+\offset(%rsp) 137d36f9479SIngo Molnar .endm 138d36f9479SIngo Molnar .macro SAVE_EXTRA_REGS_RBP offset=0 139d36f9479SIngo Molnar movq %rbp, 4*8+\offset(%rsp) 140d36f9479SIngo Molnar .endm 141d36f9479SIngo Molnar 142d36f9479SIngo Molnar .macro RESTORE_EXTRA_REGS offset=0 143d36f9479SIngo Molnar movq 0*8+\offset(%rsp), %r15 144d36f9479SIngo Molnar movq 1*8+\offset(%rsp), %r14 145d36f9479SIngo Molnar movq 2*8+\offset(%rsp), %r13 146d36f9479SIngo Molnar movq 3*8+\offset(%rsp), %r12 147d36f9479SIngo Molnar movq 4*8+\offset(%rsp), %rbp 148d36f9479SIngo Molnar movq 5*8+\offset(%rsp), %rbx 149d36f9479SIngo Molnar .endm 150d36f9479SIngo Molnar 151d36f9479SIngo Molnar .macro ZERO_EXTRA_REGS 152d36f9479SIngo Molnar xorl %r15d, %r15d 153d36f9479SIngo Molnar xorl %r14d, %r14d 154d36f9479SIngo Molnar xorl %r13d, %r13d 155d36f9479SIngo Molnar xorl %r12d, %r12d 156d36f9479SIngo Molnar xorl %ebp, %ebp 157d36f9479SIngo Molnar xorl %ebx, %ebx 158d36f9479SIngo Molnar .endm 159d36f9479SIngo Molnar 160d36f9479SIngo Molnar .macro RESTORE_C_REGS_HELPER rstor_rax=1, rstor_rcx=1, rstor_r11=1, rstor_r8910=1, rstor_rdx=1 161d36f9479SIngo Molnar .if \rstor_r11 162d36f9479SIngo Molnar movq 6*8(%rsp), %r11 163d36f9479SIngo Molnar .endif 164d36f9479SIngo Molnar .if \rstor_r8910 165d36f9479SIngo Molnar movq 7*8(%rsp), %r10 166d36f9479SIngo Molnar movq 8*8(%rsp), %r9 167d36f9479SIngo Molnar movq 9*8(%rsp), %r8 168d36f9479SIngo Molnar .endif 169d36f9479SIngo Molnar .if \rstor_rax 170d36f9479SIngo Molnar movq 10*8(%rsp), %rax 171d36f9479SIngo Molnar .endif 172d36f9479SIngo Molnar .if \rstor_rcx 173d36f9479SIngo Molnar movq 11*8(%rsp), %rcx 174d36f9479SIngo Molnar .endif 175d36f9479SIngo Molnar .if \rstor_rdx 176d36f9479SIngo Molnar movq 12*8(%rsp), %rdx 177d36f9479SIngo Molnar .endif 178d36f9479SIngo Molnar movq 13*8(%rsp), %rsi 179d36f9479SIngo Molnar movq 14*8(%rsp), %rdi 180d36f9479SIngo Molnar .endm 181d36f9479SIngo Molnar .macro RESTORE_C_REGS 182d36f9479SIngo Molnar RESTORE_C_REGS_HELPER 1,1,1,1,1 183d36f9479SIngo Molnar .endm 184d36f9479SIngo Molnar .macro RESTORE_C_REGS_EXCEPT_RAX 185d36f9479SIngo Molnar RESTORE_C_REGS_HELPER 0,1,1,1,1 186d36f9479SIngo Molnar .endm 187d36f9479SIngo Molnar .macro RESTORE_C_REGS_EXCEPT_RCX 188d36f9479SIngo Molnar RESTORE_C_REGS_HELPER 1,0,1,1,1 189d36f9479SIngo Molnar .endm 190d36f9479SIngo Molnar .macro RESTORE_C_REGS_EXCEPT_R11 191d36f9479SIngo Molnar RESTORE_C_REGS_HELPER 1,1,0,1,1 192d36f9479SIngo Molnar .endm 193d36f9479SIngo Molnar .macro RESTORE_C_REGS_EXCEPT_RCX_R11 194d36f9479SIngo Molnar RESTORE_C_REGS_HELPER 1,0,0,1,1 195d36f9479SIngo Molnar .endm 196d36f9479SIngo Molnar .macro RESTORE_RSI_RDI 197d36f9479SIngo Molnar RESTORE_C_REGS_HELPER 0,0,0,0,0 198d36f9479SIngo Molnar .endm 199d36f9479SIngo Molnar .macro RESTORE_RSI_RDI_RDX 200d36f9479SIngo Molnar RESTORE_C_REGS_HELPER 0,0,0,0,1 201d36f9479SIngo Molnar .endm 202d36f9479SIngo Molnar 203d36f9479SIngo Molnar .macro REMOVE_PT_GPREGS_FROM_STACK addskip=0 204d36f9479SIngo Molnar subq $-(15*8+\addskip), %rsp 205d36f9479SIngo Molnar .endm 206d36f9479SIngo Molnar 207d36f9479SIngo Molnar .macro icebp 208d36f9479SIngo Molnar .byte 0xf1 209d36f9479SIngo Molnar .endm 210d36f9479SIngo Molnar 211d36f9479SIngo Molnar #else /* CONFIG_X86_64 */ 212d36f9479SIngo Molnar 213d36f9479SIngo Molnar /* 214d36f9479SIngo Molnar * For 32bit only simplified versions of SAVE_ALL/RESTORE_ALL. These 215d36f9479SIngo Molnar * are different from the entry_32.S versions in not changing the segment 216d36f9479SIngo Molnar * registers. So only suitable for in kernel use, not when transitioning 217d36f9479SIngo Molnar * from or to user space. The resulting stack frame is not a standard 218d36f9479SIngo Molnar * pt_regs frame. The main use case is calling C code from assembler 219d36f9479SIngo Molnar * when all the registers need to be preserved. 220d36f9479SIngo Molnar */ 221d36f9479SIngo Molnar 222d36f9479SIngo Molnar .macro SAVE_ALL 223d36f9479SIngo Molnar pushl %eax 224d36f9479SIngo Molnar pushl %ebp 225d36f9479SIngo Molnar pushl %edi 226d36f9479SIngo Molnar pushl %esi 227d36f9479SIngo Molnar pushl %edx 228d36f9479SIngo Molnar pushl %ecx 229d36f9479SIngo Molnar pushl %ebx 230d36f9479SIngo Molnar .endm 231d36f9479SIngo Molnar 232d36f9479SIngo Molnar .macro RESTORE_ALL 233d36f9479SIngo Molnar popl %ebx 234d36f9479SIngo Molnar popl %ecx 235d36f9479SIngo Molnar popl %edx 236d36f9479SIngo Molnar popl %esi 237d36f9479SIngo Molnar popl %edi 238d36f9479SIngo Molnar popl %ebp 239d36f9479SIngo Molnar popl %eax 240d36f9479SIngo Molnar .endm 241d36f9479SIngo Molnar 242d36f9479SIngo Molnar #endif /* CONFIG_X86_64 */ 243d36f9479SIngo Molnar 244