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https://github.com/GerbilSoft/rom-properties.git
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28857f550e
Due to random shenanigans and symbol ordering, libromdata started crashing because the linker was attempting to resolve the IFUNC functions before the rpcpu functions were available. Use gcc's built-in CPU support functions instead. (It *was* working for me yesterday, then I rebooted and it stopped working until I made this change.) This requires gcc-4.8+ or clang-6.0+. An alternative workaround is using lazy binding (-Wl,-z,lazy), but this could just delay the crash until later. IfuncTest.c: Test for the CPU support functions and disable IFUNC if they aren't available.
74 lines
1.8 KiB
C
74 lines
1.8 KiB
C
/**
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* IFUNC test code
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*/
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#include <stdlib.h>
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#include <time.h>
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// Minimum glibc version requirements.
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#if defined(__GLIBC__)
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# if __GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 11)
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# error glibc-2.11 is required for IFUNC on most platforms
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# elif defined(__arm__) || defined(__thumb__) || \
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defined(__arm) || defined(_ARM) || \
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defined(_M_ARM) || defined(__aarch64__)
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# if __GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 18)
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# error glibc-2.18 is required for IFUNC on ARM
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# endif
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# endif
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#endif
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static int ifunc_method_impl1(int a, long b, char c)
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{
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return (int)(a * b + c);
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}
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static int ifunc_method_impl2(int a, long b, char c)
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{
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return (int)(a * b + c) * 2;
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}
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static int ifunc_method_impl3(int a, long b, char c)
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{
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return (int)(a * b + c) * 3;
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}
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static int ifunc_method_impl4(int a, long b, char c)
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{
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return (int)(a * b + c) * 4;
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}
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static __typeof__(&ifunc_method_impl1) ifunc_method_resolve(void)
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{
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// NOTE: Since libromdata is a shared library now, IFUNC resolvers
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// cannot call PLT functions. Otherwise, it will crash.
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// We'll use gcc's built-in CPU ID functions instead.
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// Requires gcc-4.8 or later, or clang-6.0 or later.
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time_t s = time(NULL);
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__builtin_cpu_init();
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if (__builtin_cpu_supports("sse2")) s ^= 3;
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switch (s & 3) {
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default:
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case 0: return &ifunc_method_impl1;
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case 1: return &ifunc_method_impl2;
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case 2: return &ifunc_method_impl3;
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case 3: return &ifunc_method_impl4;
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}
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return NULL;
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}
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int ifunc_method(int a, long b, char c)
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__attribute__((ifunc("ifunc_method_resolve")));
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int main(void)
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{
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// (5 * 7) + 3 == 38
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int a = 5;
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long b = 7;
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char c = 3;
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int ret = ifunc_method(a, b, c);
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if (ret == 38 || ret == 38*2 || ret == 38*3 || ret == 38*4)
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return EXIT_SUCCESS;
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return EXIT_FAILURE;
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}
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