--- ./slp_platformselect.h.mm 2012-05-12 22:56:32.000000000 +0000 +++ ./slp_platformselect.h 2013-04-08 11:28:47.000000000 +0000 @@ -32,4 +32,6 @@ #include "platform/switch_arm32_gcc.h" /* gcc using arm32 */ #elif defined(__GNUC__) && defined(__mips__) && defined(__linux__) #include "platform/switch_mips_unix.h" /* Linux/MIPS */ +#elif defined(__GNUC__) && defined(__aarch64__) +#include "platform/switch_aarch64_gcc.h" /* Aarch64 ABI */ #endif --- ./platform/switch_aarch64_gcc.h.mm 2013-04-13 21:40:23.000000000 +0000 +++ ./platform/switch_aarch64_gcc.h 2013-04-13 21:41:39.000000000 +0000 @@ -0,0 +1,76 @@ +/* + * this is the internal transfer function. + * + * HISTORY + * 13-Apr-13 Add support for strange GCC caller-save decisions + * 08-Apr-13 File creation. Michael Matz + * + * NOTES + * + * Simply save all callee saved registers + * + */ + +#define STACK_REFPLUS 1 + +#ifdef SLP_EVAL +#define STACK_MAGIC 0 +#define REGS_TO_SAVE "r19", "r20", "r21", "r22", "r23", "r24", "r25", "r26", \ + "r27", "r28", "r30" /* aka lr */, \ + "v8", "v9", "v10", "v11", \ + "v12", "v13", "v14", "v15" + +/* See below for the purpose of this function. */ +__attribute__((noinline, noclone)) int fancy_return_zero(void); +__attribute__((noinline, noclone)) int +fancy_return_zero(void) +{ + return 0; +} + +static int +slp_switch(void) +{ + int err = 0; + void *fp; + register long *stackref, stsizediff; + __asm__ volatile ("" : : : REGS_TO_SAVE); + __asm__ volatile ("str x29, %0" : "=m"(fp) : : ); + __asm__ ("mov %0, sp" : "=r" (stackref)); + { + SLP_SAVE_STATE(stackref, stsizediff); + __asm__ volatile ( + "add sp,sp,%0\n" + "add x29,x29,%0\n" + : + : "r" (stsizediff) + ); + SLP_RESTORE_STATE(); + /* SLP_SAVE_STATE macro contains some return statements + (of -1 and 1). It falls through only when + the return value of slp_save_state() is zero, which + is placed in x0. + In that case we (slp_switch) also want to return zero + (also in x0 of course). + Now, some GCC versions (seen with 4.8) think it's a + good idea to save/restore x0 around the call to + slp_restore_state(), instead of simply zeroing it + at the return below. But slp_restore_state + writes random values to the stack slot used for this + save/restore (from when it once was saved above in + SLP_SAVE_STATE, when it was still uninitialized), so + "restoring" that precious zero actually makes us + return random values. There are some ways to make + GCC not use that zero value in the normal return path + (e.g. making err volatile, but that costs a little + stack space), and the simplest is to call a function + that returns an unknown value (which happens to be zero), + so the saved/restored value is unused. */ + err = fancy_return_zero(); + } + __asm__ volatile ("ldr x29, %0" : : "m" (fp) :); + __asm__ volatile ("" : : : REGS_TO_SAVE); + return err; +} + +#endif