change otg to host mode

hc

2024-05-11 04dd17822334871b23ea2862f7798fb0e0007777

 kernel/tools/testing/selftests/rseq/rseq.c
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@@ -29,12 +29,22 @@
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 #include <dlfcn.h>
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 #include <stddef.h>
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+#include <linux/compiler.h>
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+
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 #include "../kselftest.h"
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 #include "rseq.h"
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-static const ptrdiff_t *libc_rseq_offset_p;
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-static const unsigned int *libc_rseq_size_p;
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-static const unsigned int *libc_rseq_flags_p;
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+/*
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+ * Define weak versions to play nice with binaries that are statically linked
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+ * against a libc that doesn't support registering its own rseq.
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+ */
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+__weak ptrdiff_t __rseq_offset;
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+__weak unsigned int __rseq_size;
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+__weak unsigned int __rseq_flags;
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+
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+static const ptrdiff_t *libc_rseq_offset_p = &__rseq_offset;
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+static const unsigned int *libc_rseq_size_p = &__rseq_size;
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+static const unsigned int *libc_rseq_flags_p = &__rseq_flags;
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 /* Offset from the thread pointer to the rseq area.  */
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 ptrdiff_t rseq_offset;
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@@ -108,10 +118,19 @@
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 static __attribute__((constructor))
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 void rseq_init(void)
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 {
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-	libc_rseq_offset_p = dlsym(RTLD_NEXT, "__rseq_offset");
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-	libc_rseq_size_p = dlsym(RTLD_NEXT, "__rseq_size");
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-	libc_rseq_flags_p = dlsym(RTLD_NEXT, "__rseq_flags");
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-	if (libc_rseq_size_p && libc_rseq_offset_p && libc_rseq_flags_p) {
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+	/*
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+	 * If the libc's registered rseq size isn't already valid, it may be
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+	 * because the binary is dynamically linked and not necessarily due to
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+	 * libc not having registered a restartable sequence.  Try to find the
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+	 * symbols if that's the case.
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+	 */
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+	if (!*libc_rseq_size_p) {
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+		libc_rseq_offset_p = dlsym(RTLD_NEXT, "__rseq_offset");
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+		libc_rseq_size_p = dlsym(RTLD_NEXT, "__rseq_size");
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+		libc_rseq_flags_p = dlsym(RTLD_NEXT, "__rseq_flags");
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+	}
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+	if (libc_rseq_size_p && libc_rseq_offset_p && libc_rseq_flags_p &&
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+			*libc_rseq_size_p != 0) {
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 		/* rseq registration owned by glibc */
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 		rseq_offset = *libc_rseq_offset_p;
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 		rseq_size = *libc_rseq_size_p;