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1bdda52fe9
This patch moves the vDSO setup from libc to loader code, just after the vDSO link_map setup. For static case the initialization is moved to _dl_non_dynamic_init instead. Instead of using the mangled pointer, the vDSO data is set as attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for static). It is read-only even with partial relro. It fixes BZ#24967 now that the vDSO pointer is setup earlier than malloc interposition is called. Also, vDSO calls should not be a problem for static dlopen as indicated by BZ#20802. The vDSO pointer would be zero-initialized and the syscall will be issued instead. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu, powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and sparcv9-linux-gnu. I also run some tests on mips. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
77 lines
2.0 KiB
C
77 lines
2.0 KiB
C
/* RISC-V instruction cache flushing VDSO calls
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Copyright (C) 2017-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <dl-vdso.h>
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#include <stdlib.h>
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#include <atomic.h>
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#include <sys/cachectl.h>
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#if __has_include (<asm/syscalls.h>)
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# include <asm/syscalls.h>
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#else
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# include <asm/unistd.h>
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#endif
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#include <sys/syscall.h>
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typedef int (*func_type) (void *, void *, unsigned long int);
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static int
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__riscv_flush_icache_syscall (void *start, void *end, unsigned long int flags)
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{
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return INLINE_SYSCALL (riscv_flush_icache, 3, start, end, flags);
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}
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static func_type
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__lookup_riscv_flush_icache (void)
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{
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func_type func = dl_vdso_vsym ("__vdso_flush_icache");
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/* If there is no vDSO entry then call the system call directly. All Linux
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versions provide the vDSO entry, but QEMU's user-mode emulation doesn't
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provide a vDSO. */
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if (!func)
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func = &__riscv_flush_icache_syscall;
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return func;
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}
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#ifdef SHARED
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# define INIT_ARCH()
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libc_ifunc (__riscv_flush_icache, __lookup_riscv_flush_icache ())
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#else
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int
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__riscv_flush_icache (void *start, void *end, unsigned long int flags)
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{
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static volatile func_type cached_func;
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func_type func = atomic_load_relaxed (&cached_func);
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if (!func)
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{
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func = __lookup_riscv_flush_icache ();
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atomic_store_relaxed (&cached_func, func);
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}
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return func (start, end, flags);
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}
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#endif
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