linux-user: Use ARRAY_SIZE with bitmask_transtbl

Rather than using a zero tuple to end the table, use a macro
to apply ARRAY_SIZE and pass that on to the convert functions.

This fixes two bugs in which the conversion functions required
that both the target and host masks be non-zero in order to
continue, rather than require both target and host masks be
zero in order to terminate.

This affected mmap_flags_tbl when the host does not support
all of the flags we wish to convert (e.g. MAP_UNINITIALIZED).
Mapping these flags to zero is good enough, and matches how
the kernel ignores bits that are unknown.

Fixes: 4b840f96 ("linux-user: Populate more bits in mmap_flags_tbl")
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

bsd-user/syscall_defs.h

@@ -227,7 +227,9 @@ type safe_##name(type1 arg1, type2 arg2, type3 arg3, type4 arg4, \
 }
 
 /* So far all target and host bitmasks are the same */
+#undef  target_to_host_bitmask
 #define target_to_host_bitmask(x, tbl) (x)
+#undef  host_to_target_bitmask
 #define host_to_target_bitmask(x, tbl) (x)
 
 #endif /* SYSCALL_DEFS_H */

include/exec/user/thunk.h

@@ -193,10 +193,17 @@ static inline int thunk_type_align(const argtype *type_ptr, int is_host)
     }
 }
 
-unsigned int target_to_host_bitmask(unsigned int target_mask,
-                                    const bitmask_transtbl * trans_tbl);
-unsigned int host_to_target_bitmask(unsigned int host_mask,
-                                    const bitmask_transtbl * trans_tbl);
+unsigned int target_to_host_bitmask_len(unsigned int target_mask,
+                                        const bitmask_transtbl *trans_tbl,
+                                        size_t trans_len);
+unsigned int host_to_target_bitmask_len(unsigned int host_mask,
+                                        const bitmask_transtbl * trans_tbl,
+                                        size_t trans_len);
+
+#define target_to_host_bitmask(M, T) \
+    target_to_host_bitmask_len(M, T, ARRAY_SIZE(T))
+#define host_to_target_bitmask(M, T) \
+    host_to_target_bitmask_len(M, T, ARRAY_SIZE(T))
 
 void thunk_init(unsigned int max_structs);
 

linux-user/syscall.c

@@ -455,7 +455,6 @@ static const bitmask_transtbl fcntl_flags_tbl[] = {
 #if TARGET_O_LARGEFILE != 0 || O_LARGEFILE != 0
   { TARGET_O_LARGEFILE, TARGET_O_LARGEFILE, O_LARGEFILE, O_LARGEFILE, },
 #endif
-  { 0, 0, 0, 0 }
 };
 
 _syscall2(int, sys_getcwd1, char *, buf, size_t, size)
@@ -5813,7 +5812,6 @@ static const bitmask_transtbl iflag_tbl[] = {
         { TARGET_IXOFF, TARGET_IXOFF, IXOFF, IXOFF },
         { TARGET_IMAXBEL, TARGET_IMAXBEL, IMAXBEL, IMAXBEL },
         { TARGET_IUTF8, TARGET_IUTF8, IUTF8, IUTF8},
-        { 0, 0, 0, 0 }
 };
 
 static const bitmask_transtbl oflag_tbl[] = {
@@ -5841,7 +5839,6 @@ static const bitmask_transtbl oflag_tbl[] = {
 	{ TARGET_VTDLY, TARGET_VT1, VTDLY, VT1 },
 	{ TARGET_FFDLY, TARGET_FF0, FFDLY, FF0 },
 	{ TARGET_FFDLY, TARGET_FF1, FFDLY, FF1 },
-	{ 0, 0, 0, 0 }
 };
 
 static const bitmask_transtbl cflag_tbl[] = {
@@ -5876,7 +5873,6 @@ static const bitmask_transtbl cflag_tbl[] = {
 	{ TARGET_HUPCL, TARGET_HUPCL, HUPCL, HUPCL },
 	{ TARGET_CLOCAL, TARGET_CLOCAL, CLOCAL, CLOCAL },
 	{ TARGET_CRTSCTS, TARGET_CRTSCTS, CRTSCTS, CRTSCTS },
-	{ 0, 0, 0, 0 }
 };
 
 static const bitmask_transtbl lflag_tbl[] = {
@@ -5896,7 +5892,6 @@ static const bitmask_transtbl lflag_tbl[] = {
   { TARGET_PENDIN, TARGET_PENDIN, PENDIN, PENDIN },
   { TARGET_IEXTEN, TARGET_IEXTEN, IEXTEN, IEXTEN },
   { TARGET_EXTPROC, TARGET_EXTPROC, EXTPROC, EXTPROC},
-  { 0, 0, 0, 0 }
 };
 
 static void target_to_host_termios (void *dst, const void *src)
@@ -6008,7 +6003,6 @@ static const bitmask_transtbl mmap_flags_tbl[] = {
       MAP_FIXED_NOREPLACE, MAP_FIXED_NOREPLACE },
     { TARGET_MAP_UNINITIALIZED, TARGET_MAP_UNINITIALIZED,
       MAP_UNINITIALIZED, MAP_UNINITIALIZED },
-    { 0, 0, 0, 0 }
 };
 
 /*

linux-user/thunk.c

@@ -436,29 +436,29 @@ const argtype *thunk_print(void *arg, const argtype *type_ptr)
 /* Utility function: Table-driven functions to translate bitmasks
  * between host and target formats
  */
-unsigned int target_to_host_bitmask(unsigned int target_mask,
-                                    const bitmask_transtbl * trans_tbl)
+unsigned int target_to_host_bitmask_len(unsigned int target_mask,
+                                        const bitmask_transtbl *tbl,
+                                        size_t len)
 {
-    const bitmask_transtbl *btp;
     unsigned int host_mask = 0;
 
-    for (btp = trans_tbl; btp->target_mask && btp->host_mask; btp++) {
-        if ((target_mask & btp->target_mask) == btp->target_bits) {
-            host_mask |= btp->host_bits;
+    for (size_t i = 0; i < len; ++i) {
+        if ((target_mask & tbl[i].target_mask) == tbl[i].target_bits) {
+            host_mask |= tbl[i].host_bits;
         }
     }
     return host_mask;
 }
 
-unsigned int host_to_target_bitmask(unsigned int host_mask,
-                                    const bitmask_transtbl * trans_tbl)
+unsigned int host_to_target_bitmask_len(unsigned int host_mask,
+                                        const bitmask_transtbl *tbl,
+                                        size_t len)
 {
-    const bitmask_transtbl *btp;
     unsigned int target_mask = 0;
 
-    for (btp = trans_tbl; btp->target_mask && btp->host_mask; btp++) {
-        if ((host_mask & btp->host_mask) == btp->host_bits) {
-            target_mask |= btp->target_bits;
+    for (size_t i = 0; i < len; ++i) {
+        if ((host_mask & tbl[i].host_mask) == tbl[i].host_bits) {
+            target_mask |= tbl[i].target_bits;
         }
     }
     return target_mask;