From 1c7d6584a7811b7785ae5c1e378f14b5ba0971cf Mon Sep 17 00:00:00 2001 From: takeshi_hoshina Date: Mon, 2 Nov 2020 11:07:33 +0900 Subject: basesystem-jj recipes --- ...bug-1443-which-explains-what-the-patch-do.patch | 58 ++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 external/poky/meta/recipes-core/glibc/glibc/0012-Quote-from-bug-1443-which-explains-what-the-patch-do.patch (limited to 'external/poky/meta/recipes-core/glibc/glibc/0012-Quote-from-bug-1443-which-explains-what-the-patch-do.patch') diff --git a/external/poky/meta/recipes-core/glibc/glibc/0012-Quote-from-bug-1443-which-explains-what-the-patch-do.patch b/external/poky/meta/recipes-core/glibc/glibc/0012-Quote-from-bug-1443-which-explains-what-the-patch-do.patch new file mode 100644 index 00000000..a0b46c04 --- /dev/null +++ b/external/poky/meta/recipes-core/glibc/glibc/0012-Quote-from-bug-1443-which-explains-what-the-patch-do.patch @@ -0,0 +1,58 @@ +From 8ca8e5cd78cbd37a713e1181f8f6641b57352aa8 Mon Sep 17 00:00:00 2001 +From: Khem Raj +Date: Wed, 18 Mar 2015 00:20:09 +0000 +Subject: [PATCH] Quote from bug 1443 which explains what the patch does : + + We build some random program and link it with -lust. When we run it, + it dies with a SIGSEGV before reaching main(). + + Libust.so depends on liburcu-bp.so from the usermode-rcu package. + Although libust.so is not prelinked, liburcu-bp.so IS prelinked; this + is critical. + + Libust.so uses a TLS / __thread variable that is defined in liburcu- + bp.so. There are special ARM-specific relocation types that allow two + shared libraries to share thread-specific data. This is critical too. + + One more critical issue: although liburcu-bp.so is prelinked, we can't + load it at its prelinked address, because we also link against + librt.so, and librt.so uses that address. + + The dynamic linker is forced to relink liburcu-bp.so at a different + address. In the course of relinking, it processes the special ARM + relocation record mentioned above. The prelinker has already filled + in the information, which is a short offset into a table of thread- + specific data that is allocated per-thread for each library that uses + TLS. Because the normal behavior of a relocation is to add the symbol + value to an addend stored at the address being relocated, we end up + adding the short offset to itself, doubling it. + + Now we have an awkward situation. The libust.so library doesn't know + about the addend, so its TLS data for this element is correct. The + liburcu-bp.so library has a different offset for the element. When we + go to initialize the element for the first time in liburcu-bp.so, we + write the address of the result at the doubled (broken) offset. + Later, when we refer to the address from libust.so, we check the value + at the correct offset, but it's NULL, so we eat hot SIGSEGV. + +Upstream-Status: Pending + +Signed-off-by: Andrei Dinu +Signed-off-by: Khem Raj +--- + sysdeps/arm/dl-machine.h | 2 +- + 1 file changed, 1 insertion(+), 1 deletion(-) + +diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h +index 90856779b1..a29bb86c56 100644 +--- a/sysdeps/arm/dl-machine.h ++++ b/sysdeps/arm/dl-machine.h +@@ -510,7 +510,7 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc, + + case R_ARM_TLS_DTPOFF32: + if (sym != NULL) +- *reloc_addr += sym->st_value; ++ *reloc_addr = sym->st_value; + break; + + case R_ARM_TLS_TPOFF32: -- cgit 1.2.3-korg