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kc3-lang/libffi/src/aarch64/sysv.S
Anthony Green
- src/aarch64/sysv.S
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/* Copyright (c) 2009, 2010, 2011, 2012 ARM Ltd. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ``Software''), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #define LIBFFI_ASM #include <fficonfig.h> #include <ffi.h> #define cfi_adjust_cfa_offset(off) .cfi_adjust_cfa_offset off #define cfi_rel_offset(reg, off) .cfi_rel_offset reg, off #define cfi_restore(reg) .cfi_restore reg #define cfi_def_cfa_register(reg) .cfi_def_cfa_register reg .text .globl ffi_call_SYSV .type ffi_call_SYSV, #function /* ffi_call_SYSV() Create a stack frame, setup an argument context, call the callee and extract the result. The maximum required argument stack size is provided, ffi_call_SYSV() allocates that stack space then calls the prepare_fn to populate register context and stack. The argument passing registers are loaded from the register context and the callee called, on return the register passing register are saved back to the context. Our caller will extract the return value from the final state of the saved register context. Prototype: extern unsigned ffi_call_SYSV (void (*)(struct call_context *context, unsigned char *, extended_cif *), struct call_context *context, extended_cif *, unsigned required_stack_size, void (*fn)(void)); Therefore on entry we have: x0 prepare_fn x1 &context x2 &ecif x3 bytes x4 fn This function uses the following stack frame layout: == saved x30(lr) x29(fp)-> saved x29(fp) saved x24 saved x23 saved x22 sp' -> saved x21 ... sp -> (constructed callee stack arguments) == Voila! */ #define ffi_call_SYSV_FS (8 * 4) .cfi_startproc ffi_call_SYSV: stp x29, x30, [sp, #-16]! cfi_adjust_cfa_offset (16) cfi_rel_offset (x29, 0) cfi_rel_offset (x30, 8) mov x29, sp cfi_def_cfa_register (x29) sub sp, sp, #ffi_call_SYSV_FS stp x21, x22, [sp, 0] cfi_rel_offset (x21, 0 - ffi_call_SYSV_FS) cfi_rel_offset (x22, 8 - ffi_call_SYSV_FS) stp x23, x24, [sp, 16] cfi_rel_offset (x23, 16 - ffi_call_SYSV_FS) cfi_rel_offset (x24, 24 - ffi_call_SYSV_FS) mov x21, x1 mov x22, x2 mov x24, x4 /* Allocate the stack space for the actual arguments, many arguments will be passed in registers, but we assume worst case and allocate sufficient stack for ALL of the arguments. */ sub sp, sp, x3 /* unsigned (*prepare_fn) (struct call_context *context, unsigned char *stack, extended_cif *ecif); */ mov x23, x0 mov x0, x1 mov x1, sp /* x2 already in place */ blr x23 /* Preserve the flags returned. */ mov x23, x0 /* Figure out if we should touch the vector registers. */ tbz x23, #AARCH64_FFI_WITH_V_BIT, 1f /* Load the vector argument passing registers. */ ldp q0, q1, [x21, #8*32 + 0] ldp q2, q3, [x21, #8*32 + 32] ldp q4, q5, [x21, #8*32 + 64] ldp q6, q7, [x21, #8*32 + 96] 1: /* Load the core argument passing registers. */ ldp x0, x1, [x21, #0] ldp x2, x3, [x21, #16] ldp x4, x5, [x21, #32] ldp x6, x7, [x21, #48] /* Don't forget x8 which may be holding the address of a return buffer. */ ldr x8, [x21, #8*8] blr x24 /* Save the core argument passing registers. */ stp x0, x1, [x21, #0] stp x2, x3, [x21, #16] stp x4, x5, [x21, #32] stp x6, x7, [x21, #48] /* Note nothing useful ever comes back in x8! */ /* Figure out if we should touch the vector registers. */ tbz x23, #AARCH64_FFI_WITH_V_BIT, 1f /* Save the vector argument passing registers. */ stp q0, q1, [x21, #8*32 + 0] stp q2, q3, [x21, #8*32 + 32] stp q4, q5, [x21, #8*32 + 64] stp q6, q7, [x21, #8*32 + 96] 1: /* All done, unwind our stack frame. */ ldp x21, x22, [x29, # - ffi_call_SYSV_FS] cfi_restore (x21) cfi_restore (x22) ldp x23, x24, [x29, # - ffi_call_SYSV_FS + 16] cfi_restore (x23) cfi_restore (x24) mov sp, x29 cfi_def_cfa_register (sp) ldp x29, x30, [sp], #16 cfi_adjust_cfa_offset (-16) cfi_restore (x29) cfi_restore (x30) ret .cfi_endproc .size ffi_call_SYSV, .-ffi_call_SYSV #define ffi_closure_SYSV_FS (8 * 2 + AARCH64_CALL_CONTEXT_SIZE) /* ffi_closure_SYSV Closure invocation glue. This is the low level code invoked directly by the closure trampoline to setup and call a closure. On entry x17 points to a struct trampoline_data, x16 has been clobbered all other registers are preserved. We allocate a call context and save the argument passing registers, then invoked the generic C ffi_closure_SYSV_inner() function to do all the real work, on return we load the result passing registers back from the call context. On entry extern void ffi_closure_SYSV (struct trampoline_data *); struct trampoline_data { UINT64 *ffi_closure; UINT64 flags; }; This function uses the following stack frame layout: == saved x30(lr) x29(fp)-> saved x29(fp) saved x22 saved x21 ... sp -> call_context == Voila! */ .text .globl ffi_closure_SYSV .cfi_startproc ffi_closure_SYSV: stp x29, x30, [sp, #-16]! cfi_adjust_cfa_offset (16) cfi_rel_offset (x29, 0) cfi_rel_offset (x30, 8) mov x29, sp sub sp, sp, #ffi_closure_SYSV_FS cfi_adjust_cfa_offset (ffi_closure_SYSV_FS) stp x21, x22, [x29, #-16] cfi_rel_offset (x21, 0) cfi_rel_offset (x22, 8) /* Load x21 with &call_context. */ mov x21, sp /* Preserve our struct trampoline_data * */ mov x22, x17 /* Save the rest of the argument passing registers. */ stp x0, x1, [x21, #0] stp x2, x3, [x21, #16] stp x4, x5, [x21, #32] stp x6, x7, [x21, #48] /* Don't forget we may have been given a result scratch pad address. */ str x8, [x21, #64] /* Figure out if we should touch the vector registers. */ ldr x0, [x22, #8] tbz x0, #AARCH64_FFI_WITH_V_BIT, 1f /* Save the argument passing vector registers. */ stp q0, q1, [x21, #8*32 + 0] stp q2, q3, [x21, #8*32 + 32] stp q4, q5, [x21, #8*32 + 64] stp q6, q7, [x21, #8*32 + 96] 1: /* Load &ffi_closure.. */ ldr x0, [x22, #0] mov x1, x21 /* Compute the location of the stack at the point that the trampoline was called. */ add x2, x29, #16 bl ffi_closure_SYSV_inner /* Figure out if we should touch the vector registers. */ ldr x0, [x22, #8] tbz x0, #AARCH64_FFI_WITH_V_BIT, 1f /* Load the result passing vector registers. */ ldp q0, q1, [x21, #8*32 + 0] ldp q2, q3, [x21, #8*32 + 32] ldp q4, q5, [x21, #8*32 + 64] ldp q6, q7, [x21, #8*32 + 96] 1: /* Load the result passing core registers. */ ldp x0, x1, [x21, #0] ldp x2, x3, [x21, #16] ldp x4, x5, [x21, #32] ldp x6, x7, [x21, #48] /* Note nothing usefull is returned in x8. */ /* We are done, unwind our frame. */ ldp x21, x22, [x29, #-16] cfi_restore (x21) cfi_restore (x22) mov sp, x29 cfi_adjust_cfa_offset (-ffi_closure_SYSV_FS) ldp x29, x30, [sp], #16 cfi_adjust_cfa_offset (-16) cfi_restore (x29) cfi_restore (x30) ret .cfi_endproc .size ffi_closure_SYSV, .-ffi_closure_SYSV