[PATCH 1/2] linux-user: Fix mmap2() syscall on 32-bit targets to allow file mapping beyond 4GB

[PATCH 1/2] linux-user: Fix mmap2() syscall on 32-bit targets to allow file mapping beyond 4GB

[Helge Deller]

The mmap2() syscall allows 32-bit guests to specify the offset into a
file in page units (instead of bytes, as done by mmap(2)).
On physical machines this allows 32-bit applications to map such parts
of large files which are stored beyond the 4GB limit.

Allow the same behaviour when emulating 32-bit guests with qemu.

For that switch the mmap2() function to always take an abi_ullong
(64-bit) offset parameter for target_mmap() and mmap_frag() to avoid an
arithmetical overflow when shifing a 32-bit offset parameter by
12 bits (=PAGE_SHIFT) and thus possibly overflow the abi_ulong (32-bit)
type.

Signed-off-by: Helge Deller <deller@gmx.de>
---
 linux-user/mmap.c      | 9 +++++----
 linux-user/syscall.c   | 2 +-
 linux-user/user-mmap.h | 2 +-
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 28135c9e6a..1bd60e28e6 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -192,7 +192,7 @@ error:
 /* map an incomplete host page */
 static int mmap_frag(abi_ulong real_start,
                      abi_ulong start, abi_ulong end,
-                     int prot, int flags, int fd, abi_ulong offset)
+                     int prot, int flags, int fd, abi_ullong offset)
 {
     abi_ulong real_end, addr;
     void *host_start;
@@ -430,10 +430,11 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size, abi_ulong align)

 /* NOTE: all the constants are the HOST ones */
 abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot,
-                     int flags, int fd, abi_ulong offset)
+                     int flags, int fd, abi_ullong offset)
 {
-    abi_ulong ret, end, real_start, real_end, retaddr, host_offset, host_len,
+    abi_ulong ret, end, real_start, real_end, retaddr, host_len,
               passthrough_start = -1, passthrough_end = -1;
+    abi_ullong host_offset;
     int page_flags, host_prot;

     mmap_lock();
@@ -621,7 +622,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int target_prot,
         /* map the middle (easier) */
         if (real_start < real_end) {
             void *p;
-            unsigned long offset1;
+            off_t offset1;
             if (flags & MAP_ANONYMOUS)
                 offset1 = 0;
             else
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 24cea6fb6a..e0a6550769 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -10137,7 +10137,7 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
 #endif
         ret = target_mmap(arg1, arg2, arg3,
                           target_to_host_bitmask(arg4, mmap_flags_tbl),
-                          arg5, arg6 << MMAP_SHIFT);
+                          arg5, ((abi_ullong)arg6) << MMAP_SHIFT);
         return get_errno(ret);
 #endif
     case TARGET_NR_munmap:
diff --git a/linux-user/user-mmap.h b/linux-user/user-mmap.h
index 480ce1c114..72e99000d9 100644
--- a/linux-user/user-mmap.h
+++ b/linux-user/user-mmap.h
@@ -20,7 +20,7 @@

 int target_mprotect(abi_ulong start, abi_ulong len, int prot);
 abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
-                     int flags, int fd, abi_ulong offset);
+                     int flags, int fd, abi_ullong offset);
 int target_munmap(abi_ulong start, abi_ulong len);
 abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size,
                        abi_ulong new_size, unsigned long flags,
--
2.38.1

[PATCH 2/2] linux-user: Improve strace output of pread64() and pwrite64()

[Helge Deller]

Make the strace look nicer for those two syscalls.

Signed-off-by: Helge Deller <deller@gmx.de>
---
 linux-user/strace.c    | 19 +++++++++++++++++++
 linux-user/strace.list |  4 ++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/linux-user/strace.c b/linux-user/strace.c
index aad2b62ca4..669200c4a4 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -3999,6 +3999,25 @@ print_tgkill(CPUArchState *cpu_env, const struct syscallname *name,
 }
 #endif

+#if defined(TARGET_NR_pread64) || defined(TARGET_NR_pwrite64)
+static void
+print_pread64(CPUArchState *cpu_env, const struct syscallname *name,
+        abi_long arg0, abi_long arg1, abi_long arg2,
+        abi_long arg3, abi_long arg4, abi_long arg5)
+{
+    if (regpairs_aligned(cpu_env, TARGET_NR_pread64)) {
+        arg3 = arg4;
+        arg4 = arg5;
+    }
+    print_syscall_prologue(name);
+    print_raw_param("%d", arg0, 0);
+    print_pointer(arg1, 0);
+    print_raw_param("%d", arg2, 0);
+    print_raw_param("%" PRIu64, target_offset64(arg3, arg4), 1);
+    print_syscall_epilogue(name);
+}
+#endif
+
 #ifdef TARGET_NR_statx
 static void
 print_statx(CPUArchState *cpu_env, const struct syscallname *name,
diff --git a/linux-user/strace.list b/linux-user/strace.list
index c7808ea118..6655d4f26d 100644
--- a/linux-user/strace.list
+++ b/linux-user/strace.list
@@ -1068,7 +1068,7 @@
 { TARGET_NR_prctl, "prctl" , NULL, NULL, NULL },
 #endif
 #ifdef TARGET_NR_pread64
-{ TARGET_NR_pread64, "pread64" , NULL, NULL, NULL },
+{ TARGET_NR_pread64, "pread64" , NULL, print_pread64, NULL },
 #endif
 #ifdef TARGET_NR_preadv
 { TARGET_NR_preadv, "preadv" , NULL, NULL, NULL },
@@ -1099,7 +1099,7 @@
 { TARGET_NR_putpmsg, "putpmsg" , NULL, NULL, NULL },
 #endif
 #ifdef TARGET_NR_pwrite64
-{ TARGET_NR_pwrite64, "pwrite64" , NULL, NULL, NULL },
+{ TARGET_NR_pwrite64, "pwrite64" , NULL, print_pread64, NULL },
 #endif
 #ifdef TARGET_NR_pwritev
 { TARGET_NR_pwritev, "pwritev" , NULL, NULL, NULL },
--
2.38.1