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 <del...@gmx.de>
Reviewed-by: Helge Deller <del...@gmx.de>
Reviewed-by: Akihiko Odaki <akihiko.od...@daynix.com>
Signed-off-by: Richard Henderson <richard.hender...@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 0c64aad8a5..a3aa08a13e 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -3106,6 +3106,8 @@ static void load_elf_image(const char *image_name, int
image_fd,
}
}
+ load_addr = loaddr;
+
if (pinterp_name != NULL) {
/*
* This is the main executable.
@@ -3135,11 +3137,32 @@ 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;
+ }
}
}
@@ -3154,13 +3177,13 @@ 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
