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qemu: add fix for brk

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From 6fd5944980
This commit is contained in:
Leonid Pliushch 2020-02-13 22:24:42 +02:00
parent 13ba8fa19d
commit 22a2725a2f
2 changed files with 113 additions and 1 deletions
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112
packages/qemu-system-x86_64-headless/0012-reserve-space-for-brk.patch Normal file
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@ -0,0 +1,112 @@
https://github.com/qemu/qemu/commit/6fd5944980f4ccee728ce34bdaffc117db50b34d
diff -uNr qemu-4.1.1/linux-user/elfload.c qemu-4.1.1.mod/linux-user/elfload.c
--- qemu-4.1.1/linux-user/elfload.c 2020-02-13 22:19:06.939675451 +0200
+++ qemu-4.1.1.mod/linux-user/elfload.c 2020-02-13 22:22:26.853718260 +0200
@@ -11,6 +11,7 @@
#include "disas/disas.h"
#include "qemu/path.h"
#include "qemu/guest-random.h"
+#include "qemu/units.h"
#ifdef _ARCH_PPC64
#undef ARCH_DLINFO
@@ -2340,24 +2341,51 @@
}
}
- load_addr = loaddr;
- if (ehdr->e_type == ET_DYN) {
- /* The image indicates that it can be loaded anywhere. Find a
- location that can hold the memory space required. If the
- image is pre-linked, LOADDR will be non-zero. Since we do
- not supply MAP_FIXED here we'll use that address if and
- only if it remains available. */
- load_addr = target_mmap(loaddr, hiaddr - loaddr, PROT_NONE,
- MAP_PRIVATE | MAP_ANON | MAP_NORESERVE,
- -1, 0);
- if (load_addr == -1) {
- goto exit_perror;
- }
- } else if (pinterp_name != NULL) {
- /* This is the main executable. Make sure that the low
- address does not conflict with MMAP_MIN_ADDR or the
- QEMU application itself. */
- probe_guest_base(image_name, loaddr, hiaddr);
+ if (pinterp_name != NULL) {
+ /*
+ * This is the main executable.
+ *
+ * Reserve extra space for brk.
+ * We hold on to this space while placing the interpreter
+ * and the stack, lest they be placed immediately after
+ * the data segment and block allocation from the brk.
+ *
+ * 16MB is chosen as "large enough" without being so large
+ * as to allow the result to not fit with a 32-bit guest on
+ * a 32-bit host.
+ */
+ info->reserve_brk = 16 * MiB;
+ hiaddr += info->reserve_brk;
+
+ if (ehdr->e_type == ET_EXEC) {
+ /*
+ * Make sure that the low address does not conflict with
+ * MMAP_MIN_ADDR or the QEMU application itself.
+ */
+ probe_guest_base(image_name, loaddr, hiaddr);
+ }
+ }
+
+ /*
+ * Reserve address space for all of this.
+ *
+ * In the case of ET_EXEC, we supply MAP_FIXED so that we get
+ * exactly the address range that is required.
+ *
+ * Otherwise this is ET_DYN, and we are searching for a location
+ * that can hold the memory space required. If the image is
+ * pre-linked, LOADDR will be non-zero, and the kernel should
+ * honor that address if it happens to be free.
+ *
+ * In both cases, we will overwrite pages in this range with mappings
+ * from the executable.
+ */
+ load_addr = target_mmap(loaddr, hiaddr - loaddr, PROT_NONE,
+ MAP_PRIVATE | MAP_ANON | MAP_NORESERVE |
+ (ehdr->e_type == ET_EXEC ? MAP_FIXED : 0),
+ -1, 0);
+ if (load_addr == -1) {
+ goto exit_perror;
}
load_bias = load_addr - loaddr;
@@ -2834,6 +2862,17 @@
bprm->core_dump = &elf_core_dump;
#endif
+ /*
+ * If we reserved extra space for brk, release it now.
+ * The implementation of do_brk in syscalls.c expects to be able
+ * to mmap pages in this space.
+ */
+ if (info->reserve_brk) {
+ abi_ulong start_brk = HOST_PAGE_ALIGN(info->brk);
+ abi_ulong end_brk = HOST_PAGE_ALIGN(info->brk + info->reserve_brk);
+ target_munmap(start_brk, end_brk - start_brk);
+ }
+
return 0;
}
diff -uNr qemu-4.1.1/linux-user/qemu.h qemu-4.1.1.mod/linux-user/qemu.h
--- qemu-4.1.1/linux-user/qemu.h 2019-11-14 20:06:20.000000000 +0200
+++ qemu-4.1.1.mod/linux-user/qemu.h 2020-02-13 22:22:26.854718265 +0200
@@ -36,6 +36,7 @@
abi_ulong end_data;
abi_ulong start_brk;
abi_ulong brk;
+ abi_ulong reserve_brk;
abi_ulong start_mmap;
abi_ulong start_stack;
abi_ulong stack_limit;

2
packages/qemu-system-x86_64-headless/build.sh
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@ -5,7 +5,7 @@ TERMUX_PKG_MAINTAINER="Leonid Plyushch <leonid.plyushch@gmail.com>"
# Do not update version unless you verified that it works properly.
_PACKAGE_VERSION=4.1.1
TERMUX_PKG_VERSION=1:${_PACKAGE_VERSION}
TERMUX_PKG_REVISION=2
TERMUX_PKG_REVISION=3
TERMUX_PKG_SRCURL=https://download.qemu.org/qemu-${_PACKAGE_VERSION}.tar.xz
TERMUX_PKG_SHA256="ed6fdbbdd272611446ff8036991e9b9f04a2ab2e3ffa9e79f3bab0eb9a95a1d2"
TERMUX_PKG_DEPENDS="attr, glib, libbz2, libc++, libcap, libcurl, libandroid-shmem, libgcrypt, libiconv, libjpeg-turbo, liblzo, libnfs, libpixman, libpng, libssh, libxml2, ncurses, qemu-common, resolv-conf, zlib"