| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109 |
- // SPDX-License-Identifier: Apache-2.0
- // SPDX-FileCopyrightText: 2026 The Ebitengine Authors
- //go:build linux
- #include "textflag.h"
- #include "go_asm.h"
- #include "funcdata.h"
- // S390X ELF ABI callbackasm1 implementation
- // On entry, R0 contains the callback index (set by callbackasm)
- // NOTE: We use R0 instead of R11 because R11 is callee-saved on S390X.
- //
- // S390X stack frame layout:
- // 0(R15) - back chain
- // 48(R15) - register save area (R6-R15)
- // 160(R15) - parameter area
- //
- // S390X uses R2-R6 for integer arguments (5 registers) and F0,F2,F4,F6 for floats (4 registers).
- //
- // Our frame layout (total 264 bytes, 8-byte aligned):
- // 0(R15) - back chain
- // 48(R15) - saved R6-R15 (done by STMG)
- // 160(R15) - callbackArgs struct (32 bytes: index, args, result, stackArgs)
- // 192(R15) - args array start
- //
- // Args array layout:
- // - floats F0,F2,F4,F6 (32 bytes)
- // - ints R2-R6 (40 bytes)
- // Total args array: 72 bytes, ends at 264
- //
- // Stack args in caller's frame start at old_R15+160
- #define FRAME_SIZE 264
- #define CB_ARGS 160
- #define ARGS_ARRAY 192
- #define FLOAT_OFF 0
- #define INT_OFF 32
- TEXT callbackasm1(SB), NOSPLIT|NOFRAME, $0
- NO_LOCAL_POINTERS
- // On entry, the trampoline in zcallback_s390x.s left
- // the callback index in R0 (NOT R11, since R11 is callee-saved).
- // R6 contains the 5th integer argument.
- // Save R6-R15 in caller's frame (per S390X ABI) BEFORE allocating our frame
- // STMG stores R6's current value (the 5th arg) at 48(R15)
- STMG R6, R15, 48(R15)
- // Save current stack pointer (will be back chain)
- MOVD R15, R1
- // Allocate our stack frame
- SUB $FRAME_SIZE, R15
- MOVD R1, 0(R15) // back chain
- // Save R0 (callback index) immediately - it's volatile
- MOVD R0, (CB_ARGS+0)(R15)
- // Save callback arguments to args array.
- // Layout: floats first (F0,F2,F4,F6), then ints (R2-R6)
- FMOVD F0, (ARGS_ARRAY+FLOAT_OFF+0*8)(R15)
- FMOVD F2, (ARGS_ARRAY+FLOAT_OFF+1*8)(R15)
- FMOVD F4, (ARGS_ARRAY+FLOAT_OFF+2*8)(R15)
- FMOVD F6, (ARGS_ARRAY+FLOAT_OFF+3*8)(R15)
- MOVD R2, (ARGS_ARRAY+INT_OFF+0*8)(R15)
- MOVD R3, (ARGS_ARRAY+INT_OFF+1*8)(R15)
- MOVD R4, (ARGS_ARRAY+INT_OFF+2*8)(R15)
- MOVD R5, (ARGS_ARRAY+INT_OFF+3*8)(R15)
- // R6 (5th int arg) was saved at 48(old_R15) by STMG
- // old_R15 = current R15 + FRAME_SIZE, so R6 is at 48+FRAME_SIZE(R15) = 312(R15)
- MOVD (48+FRAME_SIZE)(R15), R1
- MOVD R1, (ARGS_ARRAY+INT_OFF+4*8)(R15)
- // Finish setting up callbackArgs struct at CB_ARGS(R15)
- // struct { index uintptr; args unsafe.Pointer; result uintptr; stackArgs unsafe.Pointer }
- // Note: index was already saved earlier
- ADD $ARGS_ARRAY, R15, R1
- MOVD R1, (CB_ARGS+8)(R15) // args = address of register args
- MOVD $0, (CB_ARGS+16)(R15) // result = 0
- // stackArgs points to caller's stack arguments at old_R15+160 = R15+FRAME_SIZE+160
- ADD $(FRAME_SIZE+160), R15, R1
- MOVD R1, (CB_ARGS+24)(R15) // stackArgs = &caller_stack_args
- // Call crosscall2 with arguments in registers:
- // R2 = fn (from callbackWrap_call closure)
- // R3 = frame (address of callbackArgs)
- // R5 = ctxt (0)
- MOVD ·callbackWrap_call(SB), R2
- MOVD (R2), R2 // dereference closure to get fn
- ADD $CB_ARGS, R15, R3 // frame = &callbackArgs
- MOVD $0, R5 // ctxt = 0
- BL crosscall2(SB)
- // Get callback result into R2
- MOVD (CB_ARGS+16)(R15), R2
- // Deallocate frame
- ADD $FRAME_SIZE, R15
- // Restore R6-R15 from caller's frame
- LMG 48(R15), R6, R15
- RET
|
