From 1ac7bf149be1e35343b7f5d830d930bd8bd41fcf Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Tue, 6 Sep 2022 06:44:44 -0700 Subject: nptl: use mmap to allocate initial TLS data for static PIE on noMMU Static PIE ELFs may be loaded on noMMU linux platforms with FDPIC support, but they don't have adjustable brk, and thus cannot allocate memory for the TLS. Use mmap instead of sbrk to allocate initial TLS memory when building with static PIE support for noMMU. Signed-off-by: Max Filippov --- libpthread/nptl/sysdeps/generic/libc-tls.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/libpthread/nptl/sysdeps/generic/libc-tls.c b/libpthread/nptl/sysdeps/generic/libc-tls.c index 0c8c558d0..54f3cb0c7 100644 --- a/libpthread/nptl/sysdeps/generic/libc-tls.c +++ b/libpthread/nptl/sysdeps/generic/libc-tls.c @@ -166,10 +166,13 @@ __libc_setup_tls (size_t tcbsize, size_t tcbalign) for FDPIC MMU-less platforms: fs/binfmt_elf_fdpic.c: fix brk area overlap with stack on NOMMU https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/fs/binfmt_elf_fdpic.c?id=4ac313111018cb44ecc250445de5ccb93026a980 + Loading static PIE ELFs on noMMU is possible since the linux kernel commit + 1bde925d2354 ("fs/binfmt_elf_fdpic.c: provide NOMMU loader for regular ELF binaries") + and it is subject to the same brk restriction. */ # if defined(TLS_TCB_AT_TP) tcb_offset = roundup (memsz + GL(dl_tls_static_size), tcbalign); -# if defined(__FDPIC__) +# if defined(__FDPIC__) || (!defined(__ARCH_USE_MMU__) && defined(STATIC_PIE)) tlsblock = mmap (NULL, tcb_offset + tcbsize + max_align, PROT_READ|PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); # else @@ -177,7 +180,7 @@ __libc_setup_tls (size_t tcbsize, size_t tcbalign) # endif # elif defined(TLS_DTV_AT_TP) tcb_offset = roundup (tcbsize, align ?: 1); -# if defined(__FDPIC__) +# if defined(__FDPIC__) || (!defined(__ARCH_USE_MMU__) && defined(STATIC_PIE)) tlsblock = mmap (NULL, tcb_offset + memsz + max_align + TLS_PRE_TCB_SIZE + GL(dl_tls_static_size), PROT_READ|PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); # else -- cgit v1.2.3