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authorFlorian Weimer <fweimer@redhat.com>2020-07-12 17:53:58 +0200
committerFlorian Weimer <fweimer@redhat.com>2020-07-12 17:53:58 +0200
commit48699da1c468543ade14777819bd1b4d652709de (patch)
tree4cea82371da6e849e50b1166e242611b95576d32 /csu/libc-tls.c
parent43530ba1dc4fccd438fefa26f50977ff6bf284c7 (diff)
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elf: Support at least 32-byte alignment in static dlopen
Otherwise loading a dynamically linked libc with rseq support fails,
as result of the __rseq_abi TLS variable, which has an alignment
of 32 bytes.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Vineet Gupta <vgupta@synopsys.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Tested-by: Alistair Francis <alistair.francis@wdc.com>
Diffstat (limited to 'csu/libc-tls.c')
-rw-r--r--csu/libc-tls.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/csu/libc-tls.c b/csu/libc-tls.c
index 06e76bd395..3f1655f264 100644
--- a/csu/libc-tls.c
+++ b/csu/libc-tls.c
@@ -112,6 +112,12 @@ __libc_setup_tls (void)
   size_t tcb_offset;
   const ElfW(Phdr) *phdr;
 
+  /* libc.so with rseq has TLS with 32-byte alignment.  Static dlopen
+     requires at least 32-byte alignment as well, otherwise loading
+     libc.so will always fail.  */
+  if (max_align < 32)
+    max_align = 32;
+
   struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
 
   /* Look through the TLS segment if there is any.  */