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[PULL 05/14] linux-user: Use elf_et_dyn_base for ET_DYN with interpreter
From: |
Richard Henderson |
Subject: |
[PULL 05/14] linux-user: Use elf_et_dyn_base for ET_DYN with interpreter |
Date: |
Tue, 8 Aug 2023 14:08:47 -0700 |
Follow the lead of the linux kernel in fs/binfmt_elf.c,
in which an ET_DYN executable which uses an interpreter
(usually a PIE executable) is loaded away from where the
interpreter itself will be loaded.
Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
linux-user/elfload.c | 27 +++++++++++++++++++++++++--
1 file changed, 25 insertions(+), 2 deletions(-)
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 1b4bb2d5af..d1b278d799 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -3107,6 +3107,8 @@ static void load_elf_image(const char *image_name, int
image_fd,
}
}
+ load_addr = loaddr;
+
if (pinterp_name != NULL) {
/*
* This is the main executable.
@@ -3136,11 +3138,32 @@ static void load_elf_image(const char *image_name, int
image_fd,
*/
probe_guest_base(image_name, loaddr, hiaddr);
} else {
+ abi_ulong align;
+
/*
* The binary is dynamic, but we still need to
* select guest_base. In this case we pass a size.
*/
probe_guest_base(image_name, 0, hiaddr - loaddr);
+
+ /*
+ * Avoid collision with the loader by providing a different
+ * default load address.
+ */
+ load_addr += elf_et_dyn_base;
+
+ /*
+ * TODO: Better support for mmap alignment is desirable.
+ * Since we do not have complete control over the guest
+ * address space, we prefer the kernel to choose some address
+ * rather than force the use of LOAD_ADDR via MAP_FIXED.
+ * But without MAP_FIXED we cannot guarantee alignment,
+ * only suggest it.
+ */
+ align = pow2ceil(info->alignment);
+ if (align) {
+ load_addr &= -align;
+ }
}
}
@@ -3155,13 +3178,13 @@ static void load_elf_image(const char *image_name, int
image_fd,
*
* 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
+ * pre-linked, LOAD_ADDR 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, (size_t)hiaddr - loaddr + 1, PROT_NONE,
+ load_addr = target_mmap(load_addr, (size_t)hiaddr - loaddr + 1, PROT_NONE,
MAP_PRIVATE | MAP_ANON | MAP_NORESERVE |
(ehdr->e_type == ET_EXEC ? MAP_FIXED_NOREPLACE :
0),
-1, 0);
--
2.34.1
- [PULL 00/14] linux-user image mapping fixes, Richard Henderson, 2023/08/08
- [PULL 01/14] linux-user: Adjust task_unmapped_base for reserved_va, Richard Henderson, 2023/08/08
- [PULL 02/14] linux-user: Define TASK_UNMAPPED_BASE in $guest/target_mman.h, Richard Henderson, 2023/08/08
- [PULL 04/14] linux-user: Use MAP_FIXED_NOREPLACE for initial image mmap, Richard Henderson, 2023/08/08
- [PULL 03/14] linux-user: Define ELF_ET_DYN_BASE in $guest/target_mman.h, Richard Henderson, 2023/08/08
- [PULL 05/14] linux-user: Use elf_et_dyn_base for ET_DYN with interpreter,
Richard Henderson <=
- [PULL 06/14] linux-user: Adjust initial brk when interpreter is close to executable, Richard Henderson, 2023/08/08
- [PULL 07/14] linux-user: Do not adjust image mapping for host page size, Richard Henderson, 2023/08/08
- [PULL 08/14] linux-user: Do not adjust zero_bss for host page size, Richard Henderson, 2023/08/08
- [PULL 09/14] linux-user: Use zero_bss for PT_LOAD with no file contents too, Richard Henderson, 2023/08/08
- [PULL 10/14] util/selfmap: Rewrite using qemu/interval-tree.h, Richard Henderson, 2023/08/08
- [PULL 11/14] linux-user: Remove duplicate CPU_LOG_PAGE from probe_guest_base, Richard Henderson, 2023/08/08
- [PULL 12/14] linux-user: Consolidate guest bounds check in probe_guest_base, Richard Henderson, 2023/08/08
- [PULL 13/14] linux-user: Rewrite fixed probe_guest_base, Richard Henderson, 2023/08/08
- [PULL 14/14] linux-user: Rewrite non-fixed probe_guest_base, Richard Henderson, 2023/08/08
- Re: [PULL 00/14] linux-user image mapping fixes, Richard Henderson, 2023/08/08