mirror of
https://github.com/clearlinux/graphene.git
synced 2026-08-22 05:56:23 +00:00
Dmitrii Kuvaiskii
3b02bdc80f
Previously, LibOS (shim) layer of Graphene didn't support XSAVE area. The XSAVE area stores FP, XMM, YMM, ZMM, etc. registers and control states and is handled via FXSAVE/XSAVE and FXRSTOR/XRSTOR x86-64 instructions. This commit is the first step towards adding full- fledged XSAVE support to LibOS. It adds XSAVE related structs and functions to LibOS code, and propagates XSAVE regs/states from parent to child on thread creation via clone() (though not really correctly). New test `fp_multithread` is added to LibOS regression. Future commits will add correct XSAVE handling on syscall transitions and arriving signals.
53 lines
1.5 KiB
C
53 lines
1.5 KiB
C
/* use `-fno-builtin` compiler option to prevent nearbyint and fesetround being optimized out */
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#include <err.h>
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#include <fenv.h>
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#include <math.h>
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#include <pthread.h>
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#include <stdio.h>
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#include <stdlib.h>
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static int rounding_modes[] = {FE_TONEAREST, FE_UPWARD, FE_DOWNWARD, FE_TOWARDZERO};
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static char* get_rounding_mode(int mode) {
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switch (mode) {
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case FE_TONEAREST: return "FE_TONEAREST ";
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case FE_UPWARD: return "FE_UPWARD ";
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case FE_DOWNWARD: return "FE_DOWNWARD ";
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case FE_TOWARDZERO: return "FE_TOWARDZERO";
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}
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return "UNKNOWN";
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}
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static void* thread_fp(void* arg) {
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int mode = fegetround();
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printf("%s child: 42.5 = %.1f, -42.5 = %.1f\n", get_rounding_mode(mode),
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nearbyint(42.5), nearbyint(-42.5));
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return arg;
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}
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int main(int argc, char* argv[]) {
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int ret;
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for (int i = 0; i < sizeof(rounding_modes)/sizeof(rounding_modes[0]); i++) {
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int mode = rounding_modes[i];
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ret = fesetround(mode);
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if (ret)
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err(EXIT_FAILURE, "fesetround failed");
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pthread_t thread;
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ret = pthread_create(&thread, NULL, thread_fp, NULL);
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if (ret)
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err(EXIT_FAILURE, "pthread_create failed");
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ret = pthread_join(thread, NULL);
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if (ret)
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err(EXIT_FAILURE, "pthread_join failed");
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printf("%s parent: 42.5 = %.1f, -42.5 = %.1f\n", get_rounding_mode(mode),
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nearbyint(42.5), nearbyint(-42.5));
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}
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return 0;
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}
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