On 2023/08/02 8:27, Helge Deller wrote:
Fix the elf loader to calculate a valid TASK_UNMAPPED_BASE address for all
32-bit architectures, based on the GUEST_ADDR_MAX constant.
Additionally modify the elf loader to load dynamic pie executables at
around:
~ 0x5500000000 for 64-bit guest binaries on 64-bit host,
- 0x00300000 for 32-bit guest binaries on 64-bit host, and
- 0x00000000 for 32-bit guest binaries on 32-bit host.
Why do you change guest addresses depending on the host?
With this patch the Thread Sanitizer (TSan) application will work again,
as in commit aab613fb9597 ("linux-user: Update TASK_UNMAPPED_BASE for
aarch64").
Signed-off-by: Helge Deller <del...@gmx.de>
---
linux-user/elfload.c | 6 ++++--
linux-user/loader.h | 12 ++++++++++++
linux-user/mmap.c | 35 ++++++++++++++++++-----------------
3 files changed, 34 insertions(+), 19 deletions(-)
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 47a118e430..8f5a79b537 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -3021,6 +3021,7 @@ static void load_elf_image(const char *image_name, int
image_fd,
struct elfhdr *ehdr = (struct elfhdr *)bprm_buf;
struct elf_phdr *phdr;
abi_ulong load_addr, load_bias, loaddr, hiaddr, error;
+ unsigned long load_offset = 0;
int i, retval, prot_exec;
Error *err = NULL;
bool is_main_executable;
@@ -3121,6 +3122,7 @@ static void load_elf_image(const char *image_name, int
image_fd,
* select guest_base. In this case we pass a size.
*/
probe_guest_base(image_name, 0, hiaddr - loaddr);
+ load_offset = TASK_UNMAPPED_BASE_PIE;
}
}
@@ -3138,7 +3140,7 @@ static void load_elf_image(const char *image_name, int
image_fd,
* 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(loaddr + load_offset, (size_t)hiaddr - loaddr + 1,
PROT_NONE,
MAP_PRIVATE | MAP_ANON | MAP_NORESERVE |
(is_main_executable ? MAP_FIXED : 0),
-1, 0);
@@ -3176,7 +3178,7 @@ static void load_elf_image(const char *image_name, int
image_fd,
info->start_data = -1;
info->end_data = 0;
/* possible start for brk is behind all sections of this ELF file. */
- info->brk = TARGET_PAGE_ALIGN(hiaddr);
+ info->brk = TARGET_PAGE_ALIGN(load_offset + hiaddr);
info->elf_flags = ehdr->e_flags;
prot_exec = PROT_EXEC;
diff --git a/linux-user/loader.h b/linux-user/loader.h
index 59cbeacf24..3bbfc108eb 100644
--- a/linux-user/loader.h
+++ b/linux-user/loader.h
@@ -18,6 +18,18 @@
#ifndef LINUX_USER_LOADER_H
#define LINUX_USER_LOADER_H
+/* where to map binaries? */
+#if HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 64
+# define TASK_UNMAPPED_BASE_PIE 0x5500000000
+# define TASK_UNMAPPED_BASE 0x7000000000
+#elif HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 32
+# define TASK_UNMAPPED_BASE_PIE 0x00300000
+# define TASK_UNMAPPED_BASE (GUEST_ADDR_MAX - 0x20000000 + 1)
+#else /* HOST_LONG_BITS == 32 && TARGET_ABI_BITS == 32 */
+# define TASK_UNMAPPED_BASE_PIE 0x00000000
+# define TASK_UNMAPPED_BASE 0x40000000
+#endif
+
/*
* Read a good amount of data initially, to hopefully get all the
* program headers loaded.
diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index c624feead0..3441198e21 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -23,6 +23,7 @@
#include "user-internals.h"
#include "user-mmap.h"
#include "target_mman.h"
+#include "loader.h"
static pthread_mutex_t mmap_mutex = PTHREAD_MUTEX_INITIALIZER;
static __thread int mmap_lock_count;
@@ -295,23 +296,6 @@ static bool mmap_frag(abi_ulong real_start, abi_ulong
start, abi_ulong last,
return true;
}
-#if HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 64
-#ifdef TARGET_AARCH64
-# define TASK_UNMAPPED_BASE 0x5500000000
-#else
-# define TASK_UNMAPPED_BASE 0x4000000000
-#endif
-#elif HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 32
-#ifdef TARGET_HPPA
-# define TASK_UNMAPPED_BASE 0xfa000000
-#else
-# define TASK_UNMAPPED_BASE 0xe0000000
-#endif
-#else /* HOST_LONG_BITS == 32 && TARGET_ABI_BITS == 32 */
-# define TASK_UNMAPPED_BASE 0x40000000
-#endif
-abi_ulong mmap_next_start = TASK_UNMAPPED_BASE;
-
unsigned long last_brk;
/*
@@ -344,6 +328,23 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size,
abi_ulong align)
abi_ulong addr;
int wrapped, repeat;
+ static abi_ulong mmap_next_start;
+
+ /* initialize mmap_next_start if necessary */
+ if (!mmap_next_start) {
+ mmap_next_start = TASK_UNMAPPED_BASE;
+
+ /* do sanity checks on guest memory layout */
+ if (mmap_next_start >= GUEST_ADDR_MAX) {
+ mmap_next_start = GUEST_ADDR_MAX - 0x1000000000 + 1;
What if GUEST_ADDR_MAX < 0x1000000000? I think you can just return a
hard error when mmap_next_start >= GUEST_ADDR_MAX.
+ }
+
+ if (TASK_UNMAPPED_BASE_PIE >= mmap_next_start) {
+ fprintf(stderr, "Memory too small for PIE executables.\n");
Perhaps it's better to use error_report() for new code.
+ exit(EXIT_FAILURE);
+ }
+ }
+
align = MAX(align, qemu_host_page_size);
/* If 'start' == 0, then a default start address is used. */
--
2.41.0
