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commit ffb17e7ba3a5ba9632cee97330b325072fbe41dd
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Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
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Date: Wed Jun 10 13:40:40 2020 +0100
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rtld: Avoid using up static TLS surplus for optimizations [BZ #25051]
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On some targets static TLS surplus area can be used opportunistically
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for dynamically loaded modules such that the TLS access then becomes
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faster (TLSDESC and powerpc TLS optimization). However we don't want
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all surplus TLS to be used for this optimization because dynamically
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loaded modules with initial-exec model TLS can only use surplus TLS.
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The new contract for surplus static TLS use is:
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- libc.so can have up to 192 bytes of IE TLS,
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- other system libraries together can have up to 144 bytes of IE TLS.
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- Some "optional" static TLS is available for opportunistic use.
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The optional TLS is now tunable: rtld.optional_static_tls, so users
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can directly affect the allocated static TLS size. (Note that module
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unloading with dlclose does not reclaim static TLS. After the optional
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TLS runs out, TLS access is no longer optimized to use static TLS.)
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The default setting of rtld.optional_static_tls is 512 so the surplus
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TLS is 3*192 + 4*144 + 512 = 1664 by default, the same as before.
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Fixes BZ #25051.
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Tested on aarch64-linux-gnu and x86_64-linux-gnu.
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Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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Conflicts:
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elf/Makefile
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(Missing __libc_single_threaded downstream.)
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diff --git a/csu/libc-tls.c b/csu/libc-tls.c
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index 6f2a47dc86222407..76aa1b98ea059a43 100644
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--- a/csu/libc-tls.c
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+++ b/csu/libc-tls.c
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@@ -62,6 +62,9 @@ size_t _dl_tls_static_align;
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loaded modules with IE-model TLS or for TLSDESC optimization.
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See comments in elf/dl-tls.c where it is initialized. */
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size_t _dl_tls_static_surplus;
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+/* Remaining amount of static TLS that may be used for optimizing
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+ dynamic TLS access (e.g. with TLSDESC). */
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+size_t _dl_tls_static_optional;
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/* Generation counter for the dtv. */
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size_t _dl_tls_generation;
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diff --git a/elf/Makefile b/elf/Makefile
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index cbced7605ebe2443..8b96bfefd852b79f 100644
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--- a/elf/Makefile
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+++ b/elf/Makefile
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@@ -197,7 +197,8 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
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tst-auditmany tst-initfinilazyfail \
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tst-dlopenfail tst-dlopenfail-2 \
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tst-filterobj tst-filterobj-dlopen tst-auxobj tst-auxobj-dlopen \
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- tst-audit14 tst-audit15 tst-audit16
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+ tst-audit14 tst-audit15 tst-audit16 \
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+ tst-tls-ie tst-tls-ie-dlmopen
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# reldep9
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tests-internal += loadtest unload unload2 circleload1 \
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neededtest neededtest2 neededtest3 neededtest4 \
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@@ -313,7 +314,10 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
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tst-dlopenfailmod1 tst-dlopenfaillinkmod tst-dlopenfailmod2 \
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tst-dlopenfailmod3 \
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tst-filterobj-flt tst-filterobj-aux tst-filterobj-filtee \
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- tst-auditlogmod-1 tst-auditlogmod-2 tst-auditlogmod-3
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+ tst-auditlogmod-1 tst-auditlogmod-2 tst-auditlogmod-3 \
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+ tst-tls-ie-mod0 tst-tls-ie-mod1 tst-tls-ie-mod2 \
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+ tst-tls-ie-mod3 tst-tls-ie-mod4 tst-tls-ie-mod5 \
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+ tst-tls-ie-mod6
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# Most modules build with _ISOMAC defined, but those filtered out
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# depend on internal headers.
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@@ -1690,3 +1694,23 @@ $(objpfx)tst-auxobj: $(objpfx)tst-filterobj-aux.so
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$(objpfx)tst-auxobj-dlopen: $(libdl)
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$(objpfx)tst-auxobj.out: $(objpfx)tst-filterobj-filtee.so
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$(objpfx)tst-auxobj-dlopen.out: $(objpfx)tst-filterobj-filtee.so
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+
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+$(objpfx)tst-tls-ie: $(libdl) $(shared-thread-library)
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+$(objpfx)tst-tls-ie.out: \
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+ $(objpfx)tst-tls-ie-mod0.so \
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+ $(objpfx)tst-tls-ie-mod1.so \
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+ $(objpfx)tst-tls-ie-mod2.so \
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+ $(objpfx)tst-tls-ie-mod3.so \
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+ $(objpfx)tst-tls-ie-mod4.so \
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+ $(objpfx)tst-tls-ie-mod5.so \
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+ $(objpfx)tst-tls-ie-mod6.so
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+
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+$(objpfx)tst-tls-ie-dlmopen: $(libdl) $(shared-thread-library)
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+$(objpfx)tst-tls-ie-dlmopen.out: \
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+ $(objpfx)tst-tls-ie-mod0.so \
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+ $(objpfx)tst-tls-ie-mod1.so \
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+ $(objpfx)tst-tls-ie-mod2.so \
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+ $(objpfx)tst-tls-ie-mod3.so \
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+ $(objpfx)tst-tls-ie-mod4.so \
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+ $(objpfx)tst-tls-ie-mod5.so \
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+ $(objpfx)tst-tls-ie-mod6.so
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diff --git a/elf/dl-reloc.c b/elf/dl-reloc.c
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index afeace4d3e49180c..c6139b89d4ecddc8 100644
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--- a/elf/dl-reloc.c
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+++ b/elf/dl-reloc.c
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@@ -39,13 +39,16 @@
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/* We are trying to perform a static TLS relocation in MAP, but it was
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dynamically loaded. This can only work if there is enough surplus in
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the static TLS area already allocated for each running thread. If this
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- object's TLS segment is too big to fit, we fail. If it fits,
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- we set MAP->l_tls_offset and return.
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- This function intentionally does not return any value but signals error
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- directly, as static TLS should be rare and code handling it should
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- not be inlined as much as possible. */
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+ object's TLS segment is too big to fit, we fail with -1. If it fits,
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+ we set MAP->l_tls_offset and return 0.
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+ A portion of the surplus static TLS can be optionally used to optimize
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+ dynamic TLS access (with TLSDESC or powerpc TLS optimizations).
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+ If OPTIONAL is true then TLS is allocated for such optimization and
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+ the caller must have a fallback in case the optional portion of surplus
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+ TLS runs out. If OPTIONAL is false then the entire surplus TLS area is
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+ considered and the allocation only fails if that runs out. */
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int
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-_dl_try_allocate_static_tls (struct link_map *map)
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+_dl_try_allocate_static_tls (struct link_map *map, bool optional)
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{
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/* If we've already used the variable with dynamic access, or if the
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alignment requirements are too high, fail. */
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@@ -68,8 +71,14 @@ _dl_try_allocate_static_tls (struct link_map *map)
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size_t n = (freebytes - blsize) / map->l_tls_align;
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- size_t offset = GL(dl_tls_static_used) + (freebytes - n * map->l_tls_align
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- - map->l_tls_firstbyte_offset);
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+ /* Account optional static TLS surplus usage. */
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+ size_t use = freebytes - n * map->l_tls_align - map->l_tls_firstbyte_offset;
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+ if (optional && use > GL(dl_tls_static_optional))
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+ goto fail;
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+ else if (optional)
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+ GL(dl_tls_static_optional) -= use;
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+
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+ size_t offset = GL(dl_tls_static_used) + use;
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map->l_tls_offset = GL(dl_tls_static_used) = offset;
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#elif TLS_DTV_AT_TP
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@@ -83,6 +92,13 @@ _dl_try_allocate_static_tls (struct link_map *map)
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if (used > GL(dl_tls_static_size))
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goto fail;
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+ /* Account optional static TLS surplus usage. */
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+ size_t use = used - GL(dl_tls_static_used);
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+ if (optional && use > GL(dl_tls_static_optional))
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+ goto fail;
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+ else if (optional)
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+ GL(dl_tls_static_optional) -= use;
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+
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map->l_tls_offset = offset;
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map->l_tls_firstbyte_offset = GL(dl_tls_static_used);
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GL(dl_tls_static_used) = used;
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@@ -110,12 +126,15 @@ _dl_try_allocate_static_tls (struct link_map *map)
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return 0;
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}
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+/* This function intentionally does not return any value but signals error
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+ directly, as static TLS should be rare and code handling it should
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+ not be inlined as much as possible. */
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void
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__attribute_noinline__
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_dl_allocate_static_tls (struct link_map *map)
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{
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if (map->l_tls_offset == FORCED_DYNAMIC_TLS_OFFSET
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- || _dl_try_allocate_static_tls (map))
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+ || _dl_try_allocate_static_tls (map, false))
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{
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_dl_signal_error (0, map->l_name, NULL, N_("\
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cannot allocate memory in static TLS block"));
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diff --git a/elf/dl-tls.c b/elf/dl-tls.c
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index cfda76f6de96df57..4f8c35b7d37bfc18 100644
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--- a/elf/dl-tls.c
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+++ b/elf/dl-tls.c
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@@ -60,8 +60,6 @@
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This should be large enough to cover runtime libraries of the
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compiler such as libgomp and libraries in libc other than libc.so. */
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#define OTHER_IE_TLS 144
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-/* Size of additional surplus TLS, placeholder for TLS optimizations. */
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-#define OPT_SURPLUS_TLS 512
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/* Calculate the size of the static TLS surplus, when the given
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number of audit modules are loaded. Must be called after the
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@@ -69,13 +67,15 @@
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void
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_dl_tls_static_surplus_init (size_t naudit)
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{
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- size_t nns;
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+ size_t nns, opt_tls;
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#if HAVE_TUNABLES
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nns = TUNABLE_GET (nns, size_t, NULL);
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+ opt_tls = TUNABLE_GET (optional_static_tls, size_t, NULL);
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#else
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/* Default values of the tunables. */
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nns = 4;
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+ opt_tls = 512;
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#endif
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if (nns > DL_NNS)
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nns = DL_NNS;
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@@ -84,9 +84,10 @@ _dl_tls_static_surplus_init (size_t naudit)
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(unsigned long) naudit, (unsigned long) (DL_NNS - nns));
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nns += naudit;
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+ GL(dl_tls_static_optional) = opt_tls;
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GLRO(dl_tls_static_surplus) = ((nns - 1) * LIBC_IE_TLS
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+ nns * OTHER_IE_TLS
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- + OPT_SURPLUS_TLS);
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+ + opt_tls);
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}
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/* Out-of-memory handler. */
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diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list
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index 7337fb85062c91a7..6408a8e5ae92d2c6 100644
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--- a/elf/dl-tunables.list
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+++ b/elf/dl-tunables.list
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@@ -134,5 +134,10 @@ glibc {
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maxval: 16
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default: 4
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}
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+ optional_static_tls {
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e354a5 |
+ type: SIZE_T
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e354a5 |
+ minval: 0
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e354a5 |
+ default: 512
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+ }
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e354a5 |
}
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e354a5 |
}
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diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h
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index 9e9d5a3b28bc06c5..2fc3c91b7defe84e 100644
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e354a5 |
--- a/elf/dynamic-link.h
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+++ b/elf/dynamic-link.h
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e354a5 |
@@ -40,9 +40,10 @@
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e354a5 |
(__builtin_expect ((sym_map)->l_tls_offset \
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e354a5 |
!= FORCED_DYNAMIC_TLS_OFFSET, 1) \
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e354a5 |
&& (__builtin_expect ((sym_map)->l_tls_offset != NO_TLS_OFFSET, 1) \
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e354a5 |
- || _dl_try_allocate_static_tls (sym_map) == 0))
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e354a5 |
+ || _dl_try_allocate_static_tls (sym_map, true) == 0))
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e354a5 |
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e354a5 |
-int _dl_try_allocate_static_tls (struct link_map *map) attribute_hidden;
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e354a5 |
+int _dl_try_allocate_static_tls (struct link_map *map, bool optional)
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e354a5 |
+ attribute_hidden;
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e354a5 |
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e354a5 |
#include <elf.h>
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diff --git a/elf/tst-tls-ie-dlmopen.c b/elf/tst-tls-ie-dlmopen.c
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e354a5 |
new file mode 100644
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e354a5 |
index 0000000000000000..c7b5c688e362c861
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e354a5 |
--- /dev/null
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|
e354a5 |
+++ b/elf/tst-tls-ie-dlmopen.c
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|
e354a5 |
@@ -0,0 +1,112 @@
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|
e354a5 |
+/* Test dlopen of modules with initial-exec TLS after dlmopen.
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e354a5 |
+ Copyright (C) 2016-2020 Free Software Foundation, Inc.
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|
e354a5 |
+ This file is part of the GNU C Library.
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+
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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
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+ License as published by the Free Software Foundation; either
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e354a5 |
+ version 2.1 of the License, or (at your option) any later version.
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|
e354a5 |
+
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|
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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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|
|
e354a5 |
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
|
e354a5 |
+ Lesser General Public License for more details.
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ You should have received a copy of the GNU Lesser General Public
|
|
|
e354a5 |
+ License along with the GNU C Library; if not, see
|
|
|
e354a5 |
+ <https://www.gnu.org/licenses/>. */
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+/* This test tries to check that surplus static TLS is not used up for
|
|
|
e354a5 |
+ dynamic TLS optimizations and 4*144 = 576 bytes of static TLS is
|
|
|
e354a5 |
+ still available for dlopening modules with initial-exec TLS after 3
|
|
|
e354a5 |
+ new dlmopen namespaces are created. It depends on rtld.nns=4 and
|
|
|
e354a5 |
+ rtld.optional_static_tls=512 tunable settings. */
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+#include <errno.h>
|
|
|
e354a5 |
+#include <pthread.h>
|
|
|
e354a5 |
+#include <stdio.h>
|
|
|
e354a5 |
+#include <stdlib.h>
|
|
|
e354a5 |
+#include <string.h>
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+static int do_test (void);
|
|
|
e354a5 |
+#include <support/xthread.h>
|
|
|
e354a5 |
+#include <support/xdlfcn.h>
|
|
|
e354a5 |
+#include <support/check.h>
|
|
|
e354a5 |
+#include <support/test-driver.c>
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+/* Have some big TLS in the main exe: should not use surplus TLS. */
|
|
|
e354a5 |
+__thread char maintls[1000];
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+static pthread_barrier_t barrier;
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+/* Forces multi-threaded behaviour. */
|
|
|
e354a5 |
+static void *
|
|
|
e354a5 |
+blocked_thread_func (void *closure)
|
|
|
e354a5 |
+{
|
|
|
e354a5 |
+ xpthread_barrier_wait (&barrier);
|
|
|
e354a5 |
+ /* TLS load and access tests run here in the main thread. */
|
|
|
e354a5 |
+ xpthread_barrier_wait (&barrier);
|
|
|
e354a5 |
+ return NULL;
|
|
|
e354a5 |
+}
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+static void *
|
|
|
e354a5 |
+load_and_access (Lmid_t lmid, const char *mod, const char *func)
|
|
|
e354a5 |
+{
|
|
|
e354a5 |
+ /* Load module with TLS. */
|
|
|
e354a5 |
+ void *p = xdlmopen (lmid, mod, RTLD_NOW);
|
|
|
e354a5 |
+ /* Access the TLS variable to ensure it is allocated. */
|
|
|
e354a5 |
+ void (*f) (void) = (void (*) (void))xdlsym (p, func);
|
|
|
e354a5 |
+ f ();
|
|
|
e354a5 |
+ return p;
|
|
|
e354a5 |
+}
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+static int
|
|
|
e354a5 |
+do_test (void)
|
|
|
e354a5 |
+{
|
|
|
e354a5 |
+ void *mods[5];
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ {
|
|
|
e354a5 |
+ int ret = pthread_barrier_init (&barrier, NULL, 2);
|
|
|
e354a5 |
+ if (ret != 0)
|
|
|
e354a5 |
+ {
|
|
|
e354a5 |
+ errno = ret;
|
|
|
e354a5 |
+ printf ("error: pthread_barrier_init: %m\n");
|
|
|
e354a5 |
+ exit (1);
|
|
|
e354a5 |
+ }
|
|
|
e354a5 |
+ }
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ pthread_t blocked_thread = xpthread_create (NULL, blocked_thread_func, NULL);
|
|
|
e354a5 |
+ xpthread_barrier_wait (&barrier);
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ printf ("maintls[%zu]:\t %p .. %p\n",
|
|
|
e354a5 |
+ sizeof maintls, maintls, maintls + sizeof maintls);
|
|
|
e354a5 |
+ memset (maintls, 1, sizeof maintls);
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ /* Load modules with dynamic TLS (use surplus static TLS for libc
|
|
|
e354a5 |
+ in new namespaces and may be for TLS optimizations too). */
|
|
|
e354a5 |
+ mods[0] = load_and_access (LM_ID_BASE, "tst-tls-ie-mod0.so", "access0");
|
|
|
e354a5 |
+ mods[1] = load_and_access (LM_ID_NEWLM, "tst-tls-ie-mod1.so", "access1");
|
|
|
e354a5 |
+ mods[2] = load_and_access (LM_ID_NEWLM, "tst-tls-ie-mod2.so", "access2");
|
|
|
e354a5 |
+ mods[3] = load_and_access (LM_ID_NEWLM, "tst-tls-ie-mod3.so", "access3");
|
|
|
e354a5 |
+ /* Load modules with initial-exec TLS (can only use surplus static TLS). */
|
|
|
e354a5 |
+ mods[4] = load_and_access (LM_ID_BASE, "tst-tls-ie-mod6.so", "access6");
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ /* Here 576 bytes + 3 * libc use of surplus static TLS is in use so less
|
|
|
e354a5 |
+ than 1024 bytes are available (exact number depends on TLS optimizations
|
|
|
e354a5 |
+ and the libc TLS use). */
|
|
|
e354a5 |
+ printf ("The next dlmopen should fail...\n");
|
|
|
e354a5 |
+ void *p = dlmopen (LM_ID_BASE, "tst-tls-ie-mod4.so", RTLD_NOW);
|
|
|
e354a5 |
+ if (p != NULL)
|
|
|
e354a5 |
+ FAIL_EXIT1 ("error: expected dlmopen to fail because there is "
|
|
|
e354a5 |
+ "not enough surplus static TLS.\n");
|
|
|
e354a5 |
+ printf ("...OK failed with: %s.\n", dlerror ());
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ xpthread_barrier_wait (&barrier);
|
|
|
e354a5 |
+ xpthread_join (blocked_thread);
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ /* Close the modules. */
|
|
|
e354a5 |
+ for (int i = 0; i < 5; ++i)
|
|
|
e354a5 |
+ xdlclose (mods[i]);
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ return 0;
|
|
|
e354a5 |
+}
|
|
|
e354a5 |
diff --git a/elf/tst-tls-ie-mod.h b/elf/tst-tls-ie-mod.h
|
|
|
e354a5 |
new file mode 100644
|
|
|
e354a5 |
index 0000000000000000..46b362a9b783d214
|
|
|
e354a5 |
--- /dev/null
|
|
|
e354a5 |
+++ b/elf/tst-tls-ie-mod.h
|
|
|
e354a5 |
@@ -0,0 +1,40 @@
|
|
|
e354a5 |
+/* Module with specified TLS size and model.
|
|
|
e354a5 |
+ Copyright (C) 2020 Free Software Foundation, Inc.
|
|
|
e354a5 |
+ This file is part of the GNU C Library.
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ The GNU C Library is free software; you can redistribute it and/or
|
|
|
e354a5 |
+ modify it under the terms of the GNU Lesser General Public
|
|
|
e354a5 |
+ License as published by the Free Software Foundation; either
|
|
|
e354a5 |
+ version 2.1 of the License, or (at your option) any later version.
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ The GNU C Library is distributed in the hope that it will be useful,
|
|
|
e354a5 |
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
|
e354a5 |
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
|
e354a5 |
+ Lesser General Public License for more details.
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ You should have received a copy of the GNU Lesser General Public
|
|
|
e354a5 |
+ License along with the GNU C Library; if not, see
|
|
|
e354a5 |
+ <https://www.gnu.org/licenses/>. */
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+/* This file is parameterized by macros N, SIZE and MODEL. */
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+#include <stdio.h>
|
|
|
e354a5 |
+#include <string.h>
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+#define CONCATX(x, y) x ## y
|
|
|
e354a5 |
+#define CONCAT(x, y) CONCATX (x, y)
|
|
|
e354a5 |
+#define STRX(x) #x
|
|
|
e354a5 |
+#define STR(x) STRX (x)
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+#define VAR CONCAT (var, N)
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+__attribute__ ((aligned (8), tls_model (MODEL)))
|
|
|
e354a5 |
+__thread char VAR[SIZE];
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+void
|
|
|
e354a5 |
+CONCAT (access, N) (void)
|
|
|
e354a5 |
+{
|
|
|
e354a5 |
+ printf (STR (VAR) "[%d]:\t %p .. %p " MODEL "\n", SIZE, VAR, VAR + SIZE);
|
|
|
e354a5 |
+ fflush (stdout);
|
|
|
e354a5 |
+ memset (VAR, 1, SIZE);
|
|
|
e354a5 |
+}
|
|
|
e354a5 |
diff --git a/elf/tst-tls-ie-mod0.c b/elf/tst-tls-ie-mod0.c
|
|
|
e354a5 |
new file mode 100644
|
|
|
e354a5 |
index 0000000000000000..2450686e400e1141
|
|
|
e354a5 |
--- /dev/null
|
|
|
e354a5 |
+++ b/elf/tst-tls-ie-mod0.c
|
|
|
e354a5 |
@@ -0,0 +1,4 @@
|
|
|
e354a5 |
+#define N 0
|
|
|
e354a5 |
+#define SIZE 480
|
|
|
e354a5 |
+#define MODEL "global-dynamic"
|
|
|
e354a5 |
+#include "tst-tls-ie-mod.h"
|
|
|
e354a5 |
diff --git a/elf/tst-tls-ie-mod1.c b/elf/tst-tls-ie-mod1.c
|
|
|
e354a5 |
new file mode 100644
|
|
|
e354a5 |
index 0000000000000000..849ff91e53b0a518
|
|
|
e354a5 |
--- /dev/null
|
|
|
e354a5 |
+++ b/elf/tst-tls-ie-mod1.c
|
|
|
e354a5 |
@@ -0,0 +1,4 @@
|
|
|
e354a5 |
+#define N 1
|
|
|
e354a5 |
+#define SIZE 120
|
|
|
e354a5 |
+#define MODEL "global-dynamic"
|
|
|
e354a5 |
+#include "tst-tls-ie-mod.h"
|
|
|
e354a5 |
diff --git a/elf/tst-tls-ie-mod2.c b/elf/tst-tls-ie-mod2.c
|
|
|
e354a5 |
new file mode 100644
|
|
|
e354a5 |
index 0000000000000000..23915ab67bab0ada
|
|
|
e354a5 |
--- /dev/null
|
|
|
e354a5 |
+++ b/elf/tst-tls-ie-mod2.c
|
|
|
e354a5 |
@@ -0,0 +1,4 @@
|
|
|
e354a5 |
+#define N 2
|
|
|
e354a5 |
+#define SIZE 24
|
|
|
e354a5 |
+#define MODEL "global-dynamic"
|
|
|
e354a5 |
+#include "tst-tls-ie-mod.h"
|
|
|
e354a5 |
diff --git a/elf/tst-tls-ie-mod3.c b/elf/tst-tls-ie-mod3.c
|
|
|
e354a5 |
new file mode 100644
|
|
|
e354a5 |
index 0000000000000000..5395f844a5999ea9
|
|
|
e354a5 |
--- /dev/null
|
|
|
e354a5 |
+++ b/elf/tst-tls-ie-mod3.c
|
|
|
e354a5 |
@@ -0,0 +1,4 @@
|
|
|
e354a5 |
+#define N 3
|
|
|
e354a5 |
+#define SIZE 16
|
|
|
e354a5 |
+#define MODEL "global-dynamic"
|
|
|
e354a5 |
+#include "tst-tls-ie-mod.h"
|
|
|
e354a5 |
diff --git a/elf/tst-tls-ie-mod4.c b/elf/tst-tls-ie-mod4.c
|
|
|
e354a5 |
new file mode 100644
|
|
|
e354a5 |
index 0000000000000000..93ac2eacae292d86
|
|
|
e354a5 |
--- /dev/null
|
|
|
e354a5 |
+++ b/elf/tst-tls-ie-mod4.c
|
|
|
e354a5 |
@@ -0,0 +1,4 @@
|
|
|
e354a5 |
+#define N 4
|
|
|
e354a5 |
+#define SIZE 1024
|
|
|
e354a5 |
+#define MODEL "initial-exec"
|
|
|
e354a5 |
+#include "tst-tls-ie-mod.h"
|
|
|
e354a5 |
diff --git a/elf/tst-tls-ie-mod5.c b/elf/tst-tls-ie-mod5.c
|
|
|
e354a5 |
new file mode 100644
|
|
|
e354a5 |
index 0000000000000000..84b3fd285b5b5a3e
|
|
|
e354a5 |
--- /dev/null
|
|
|
e354a5 |
+++ b/elf/tst-tls-ie-mod5.c
|
|
|
e354a5 |
@@ -0,0 +1,4 @@
|
|
|
e354a5 |
+#define N 5
|
|
|
e354a5 |
+#define SIZE 128
|
|
|
e354a5 |
+#define MODEL "initial-exec"
|
|
|
e354a5 |
+#include "tst-tls-ie-mod.h"
|
|
|
e354a5 |
diff --git a/elf/tst-tls-ie-mod6.c b/elf/tst-tls-ie-mod6.c
|
|
|
e354a5 |
new file mode 100644
|
|
|
e354a5 |
index 0000000000000000..c736bf0684f3b08f
|
|
|
e354a5 |
--- /dev/null
|
|
|
e354a5 |
+++ b/elf/tst-tls-ie-mod6.c
|
|
|
e354a5 |
@@ -0,0 +1,4 @@
|
|
|
e354a5 |
+#define N 6
|
|
|
e354a5 |
+#define SIZE 576
|
|
|
e354a5 |
+#define MODEL "initial-exec"
|
|
|
e354a5 |
+#include "tst-tls-ie-mod.h"
|
|
|
e354a5 |
diff --git a/elf/tst-tls-ie.c b/elf/tst-tls-ie.c
|
|
|
e354a5 |
new file mode 100644
|
|
|
e354a5 |
index 0000000000000000..2dc0894480417389
|
|
|
e354a5 |
--- /dev/null
|
|
|
e354a5 |
+++ b/elf/tst-tls-ie.c
|
|
|
e354a5 |
@@ -0,0 +1,111 @@
|
|
|
e354a5 |
+/* Test dlopen of modules with initial-exec TLS.
|
|
|
e354a5 |
+ Copyright (C) 2016-2020 Free Software Foundation, Inc.
|
|
|
e354a5 |
+ This file is part of the GNU C Library.
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ The GNU C Library is free software; you can redistribute it and/or
|
|
|
e354a5 |
+ modify it under the terms of the GNU Lesser General Public
|
|
|
e354a5 |
+ License as published by the Free Software Foundation; either
|
|
|
e354a5 |
+ version 2.1 of the License, or (at your option) any later version.
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ The GNU C Library is distributed in the hope that it will be useful,
|
|
|
e354a5 |
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
|
e354a5 |
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
|
e354a5 |
+ Lesser General Public License for more details.
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ You should have received a copy of the GNU Lesser General Public
|
|
|
e354a5 |
+ License along with the GNU C Library; if not, see
|
|
|
e354a5 |
+ <https://www.gnu.org/licenses/>. */
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+/* This test tries to check that surplus static TLS is not used up for
|
|
|
e354a5 |
+ dynamic TLS optimizations and 3*192 + 4*144 = 1152 bytes of static
|
|
|
e354a5 |
+ TLS is available for dlopening modules with initial-exec TLS. It
|
|
|
e354a5 |
+ depends on rtld.nns=4 and rtld.optional_static_tls=512 tunable setting. */
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+#include <errno.h>
|
|
|
e354a5 |
+#include <pthread.h>
|
|
|
e354a5 |
+#include <stdio.h>
|
|
|
e354a5 |
+#include <stdlib.h>
|
|
|
e354a5 |
+#include <string.h>
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+static int do_test (void);
|
|
|
e354a5 |
+#include <support/xthread.h>
|
|
|
e354a5 |
+#include <support/xdlfcn.h>
|
|
|
e354a5 |
+#include <support/check.h>
|
|
|
e354a5 |
+#include <support/test-driver.c>
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+/* Have some big TLS in the main exe: should not use surplus TLS. */
|
|
|
e354a5 |
+__thread char maintls[1000];
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+static pthread_barrier_t barrier;
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+/* Forces multi-threaded behaviour. */
|
|
|
e354a5 |
+static void *
|
|
|
e354a5 |
+blocked_thread_func (void *closure)
|
|
|
e354a5 |
+{
|
|
|
e354a5 |
+ xpthread_barrier_wait (&barrier);
|
|
|
e354a5 |
+ /* TLS load and access tests run here in the main thread. */
|
|
|
e354a5 |
+ xpthread_barrier_wait (&barrier);
|
|
|
e354a5 |
+ return NULL;
|
|
|
e354a5 |
+}
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+static void *
|
|
|
e354a5 |
+load_and_access (const char *mod, const char *func)
|
|
|
e354a5 |
+{
|
|
|
e354a5 |
+ /* Load module with TLS. */
|
|
|
e354a5 |
+ void *p = xdlopen (mod, RTLD_NOW);
|
|
|
e354a5 |
+ /* Access the TLS variable to ensure it is allocated. */
|
|
|
e354a5 |
+ void (*f) (void) = (void (*) (void))xdlsym (p, func);
|
|
|
e354a5 |
+ f ();
|
|
|
e354a5 |
+ return p;
|
|
|
e354a5 |
+}
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+static int
|
|
|
e354a5 |
+do_test (void)
|
|
|
e354a5 |
+{
|
|
|
e354a5 |
+ void *mods[6];
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ {
|
|
|
e354a5 |
+ int ret = pthread_barrier_init (&barrier, NULL, 2);
|
|
|
e354a5 |
+ if (ret != 0)
|
|
|
e354a5 |
+ {
|
|
|
e354a5 |
+ errno = ret;
|
|
|
e354a5 |
+ printf ("error: pthread_barrier_init: %m\n");
|
|
|
e354a5 |
+ exit (1);
|
|
|
e354a5 |
+ }
|
|
|
e354a5 |
+ }
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ pthread_t blocked_thread = xpthread_create (NULL, blocked_thread_func, NULL);
|
|
|
e354a5 |
+ xpthread_barrier_wait (&barrier);
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ printf ("maintls[%zu]:\t %p .. %p\n",
|
|
|
e354a5 |
+ sizeof maintls, maintls, maintls + sizeof maintls);
|
|
|
e354a5 |
+ memset (maintls, 1, sizeof maintls);
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ /* Load modules with dynamic TLS (may use surplus static TLS
|
|
|
e354a5 |
+ opportunistically). */
|
|
|
e354a5 |
+ mods[0] = load_and_access ("tst-tls-ie-mod0.so", "access0");
|
|
|
e354a5 |
+ mods[1] = load_and_access ("tst-tls-ie-mod1.so", "access1");
|
|
|
e354a5 |
+ mods[2] = load_and_access ("tst-tls-ie-mod2.so", "access2");
|
|
|
e354a5 |
+ mods[3] = load_and_access ("tst-tls-ie-mod3.so", "access3");
|
|
|
e354a5 |
+ /* Load modules with initial-exec TLS (can only use surplus static TLS). */
|
|
|
e354a5 |
+ mods[4] = load_and_access ("tst-tls-ie-mod4.so", "access4");
|
|
|
e354a5 |
+ mods[5] = load_and_access ("tst-tls-ie-mod5.so", "access5");
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ /* Here 1152 bytes of surplus static TLS is in use and at most 512 bytes
|
|
|
e354a5 |
+ are available (depending on TLS optimizations). */
|
|
|
e354a5 |
+ printf ("The next dlopen should fail...\n");
|
|
|
e354a5 |
+ void *p = dlopen ("tst-tls-ie-mod6.so", RTLD_NOW);
|
|
|
e354a5 |
+ if (p != NULL)
|
|
|
e354a5 |
+ FAIL_EXIT1 ("error: expected dlopen to fail because there is "
|
|
|
e354a5 |
+ "not enough surplus static TLS.\n");
|
|
|
e354a5 |
+ printf ("...OK failed with: %s.\n", dlerror ());
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ xpthread_barrier_wait (&barrier);
|
|
|
e354a5 |
+ xpthread_join (blocked_thread);
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ /* Close the modules. */
|
|
|
e354a5 |
+ for (int i = 0; i < 6; ++i)
|
|
|
e354a5 |
+ xdlclose (mods[i]);
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+ return 0;
|
|
|
e354a5 |
+}
|
|
|
e354a5 |
diff --git a/manual/tunables.texi b/manual/tunables.texi
|
|
|
e354a5 |
index e6a3e9a2cf5c959c..bd737b5d57080462 100644
|
|
|
e354a5 |
--- a/manual/tunables.texi
|
|
|
e354a5 |
+++ b/manual/tunables.texi
|
|
|
e354a5 |
@@ -249,6 +249,23 @@ increase the per-thread memory usage as necessary, so this tunable does
|
|
|
e354a5 |
not need to be changed to allow many audit modules e.g. via @env{LD_AUDIT}.
|
|
|
e354a5 |
@end deftp
|
|
|
e354a5 |
|
|
|
e354a5 |
+@deftp Tunable glibc.rtld.optional_static_tls
|
|
|
e354a5 |
+Sets the amount of surplus static TLS in bytes to allocate at program
|
|
|
e354a5 |
+startup. Every thread created allocates this amount of specified surplus
|
|
|
e354a5 |
+static TLS. This is a minimum value and additional space may be allocated
|
|
|
e354a5 |
+for internal purposes including alignment. Optional static TLS is used for
|
|
|
e354a5 |
+optimizing dynamic TLS access for platforms that support such optimizations
|
|
|
e354a5 |
+e.g. TLS descriptors or optimized TLS access for POWER (@code{DT_PPC64_OPT}
|
|
|
e354a5 |
+and @code{DT_PPC_OPT}). In order to make the best use of such optimizations
|
|
|
e354a5 |
+the value should be as many bytes as would be required to hold all TLS
|
|
|
e354a5 |
+variables in all dynamic loaded shared libraries. The value cannot be known
|
|
|
e354a5 |
+by the dynamic loader because it doesn't know the expected set of shared
|
|
|
e354a5 |
+libraries which will be loaded. The existing static TLS space cannot be
|
|
|
e354a5 |
+changed once allocated at process startup. The default allocation of
|
|
|
e354a5 |
+optional static TLS is 512 bytes and is allocated in every thread.
|
|
|
e354a5 |
+@end deftp
|
|
|
e354a5 |
+
|
|
|
e354a5 |
+
|
|
|
e354a5 |
@node Elision Tunables
|
|
|
e354a5 |
@section Elision Tunables
|
|
|
e354a5 |
@cindex elision tunables
|
|
|
e354a5 |
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
|
|
|
e354a5 |
index 293f3ab5a496afdf..37f1915b0c75a020 100644
|
|
|
e354a5 |
--- a/sysdeps/generic/ldsodefs.h
|
|
|
e354a5 |
+++ b/sysdeps/generic/ldsodefs.h
|
|
|
e354a5 |
@@ -441,6 +441,9 @@ struct rtld_global
|
|
|
e354a5 |
EXTERN size_t _dl_tls_static_used;
|
|
|
e354a5 |
/* Alignment requirement of the static TLS block. */
|
|
|
e354a5 |
EXTERN size_t _dl_tls_static_align;
|
|
|
e354a5 |
+ /* Remaining amount of static TLS that may be used for optimizing
|
|
|
e354a5 |
+ dynamic TLS access (e.g. with TLSDESC). */
|
|
|
e354a5 |
+ EXTERN size_t _dl_tls_static_optional;
|
|
|
e354a5 |
|
|
|
e354a5 |
/* Number of additional entries in the slotinfo array of each slotinfo
|
|
|
e354a5 |
list element. A large number makes it almost certain take we never
|