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elf: Move vDSO setup to rtld (BZ#24967)

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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>
This commit is contained in:
Adhemerval Zanella
2019-11-29 10:44:59 -03:00
parent 57013650f7
commit 1bdda52fe9
31 changed files with 258 additions and 290 deletions
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4
sysdeps/unix/sysv/linux/riscv/Makefile
View File

@ -1,7 +1,3 @@
ifeq ($(subdir),elf)
sysdep_routines += dl-vdso
endif
ifeq ($(subdir),misc)
sysdep_headers += sys/cachectl.h
sysdep_routines += flush-icache

2
sysdeps/unix/sysv/linux/riscv/flush-icache.c
View File

@ -39,7 +39,7 @@ __riscv_flush_icache_syscall (void *start, void *end, unsigned long int flags)
static func_type
__lookup_riscv_flush_icache (void)
{
func_type func = get_vdso_symbol ("__vdso_flush_icache");
func_type func = dl_vdso_vsym ("__vdso_flush_icache");
/* If there is no vDSO entry then call the system call directly. All Linux
versions provide the vDSO entry, but QEMU's user-mode emulation doesn't