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| author | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2020-07-06 10:21:16 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2020-07-06 10:21:16 +0200 |
| commit | 0c76fc3c2b346dc5401dc055d97d4279632b0fb3 (patch) | |
| tree | 67d7a99ad801c38a137fbb9d08ac54137bb901b9 /elf | |
| parent | f9cf87353772ca370b7bb901d86365a564fba49f (diff) | |
| download | glibc-0c76fc3c2b346dc5401dc055d97d4279632b0fb3.tar.gz glibc-0c76fc3c2b346dc5401dc055d97d4279632b0fb3.tar.xz glibc-0c76fc3c2b346dc5401dc055d97d4279632b0fb3.zip | |
Linux: Perform rseq registration at C startup and thread creation
Register rseq TLS for each thread (including main), and unregister for each thread (excluding main). "rseq" stands for Restartable Sequences. See the rseq(2) man page proposed here: https://lkml.org/lkml/2018/9/19/647 Those are based on glibc master branch commit 3ee1e0ec5c. The rseq system call was merged into Linux 4.18. The TLS_STATIC_SURPLUS define is increased to leave additional room for dlopen'd initial-exec TLS, which keeps elf/tst-auditmany working. The increase (76 bytes) is larger than 32 bytes because it has not been increased in quite a while. The cost in terms of additional TLS storage is quite significant, but it will also obscure some initial-exec-related dlopen failures.
Diffstat (limited to 'elf')
| -rw-r--r-- | elf/dl-tls.c | 8 | ||||
| -rw-r--r-- | elf/libc_early_init.c | 4 |
2 files changed, 11 insertions, 1 deletions
diff --git a/elf/dl-tls.c b/elf/dl-tls.c index fa03234610..ca13778ca9 100644 --- a/elf/dl-tls.c +++ b/elf/dl-tls.c @@ -31,7 +31,7 @@ /* Amount of excess space to allocate in the static TLS area to allow dynamic loading of modules defining IE-model TLS data. */ -#define TLS_STATIC_SURPLUS 64 + DL_NNS * 100 +#define TLS_STATIC_SURPLUS 64 + DL_NNS * 176 /* Out-of-memory handler. */ @@ -134,6 +134,12 @@ void _dl_determine_tlsoffset (void) { size_t max_align = TLS_TCB_ALIGN; + /* libc.so with rseq has TLS with 32-byte alignment. Since TLS is + initialized before audit modules are loaded and slotinfo + information is available, this is not taken into account below in + the audit case. */ + max_align = MAX (max_align, 32U); + size_t freetop = 0; size_t freebottom = 0; diff --git a/elf/libc_early_init.c b/elf/libc_early_init.c index e6c64fb526..f0fcf6448e 100644 --- a/elf/libc_early_init.c +++ b/elf/libc_early_init.c @@ -18,10 +18,14 @@ #include <ctype.h> #include <libc-early-init.h> +#include <rseq-internal.h> void __libc_early_init (_Bool initial) { /* Initialize ctype data. */ __ctype_init (); + /* Register rseq ABI to the kernel for the main program's libc. */ + if (initial) + rseq_register_current_thread (); } |