m68k: align bootinfo strings and data to 4 bytes

Various tools, such as kexec-tools and m68k-bootinfo, expect each
bootinfo entry to be aligned to 4 bytes, not 2 bytes. So adjust the
padding to fill this out as such.

Also, break apart the padding additions from the other field length
additions, so that it's more clear why these magic numbers are being
added, and comment them too.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20220926113900.1256630-2-Jason@zx2c4.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

diff --git a/hw/m68k/bootinfo.h b/hw/m68k/bootinfo.h
index bd8b212fd35ce216917e07eb67783b5b69f1e11b..897162b8189c56cb57845171f494d5e6e0f05b48 100644 (file)
--- a/hw/m68k/bootinfo.h
+++ b/hw/m68k/bootinfo.h
@@ -48,13 +48,14 @@
         stw_phys(as, base, id); \
         base += 2; \
         stw_phys(as, base, \
-                 (sizeof(struct bi_record) + strlen(string) + 2) & ~1); \
+                 (sizeof(struct bi_record) + strlen(string) + \
+                  1 /* null termination */ + 3 /* padding */) & ~3); \
         base += 2; \
         for (i = 0; string[i]; i++) { \
             stb_phys(as, base++, string[i]); \
         } \
         stb_phys(as, base++, 0); \
-        base = (base + 1) & ~1; \
+        base = (base + 3) & ~3; \
     } while (0)
 
 #define BOOTINFODATA(as, base, id, data, len) \
@@ -63,13 +64,14 @@
         stw_phys(as, base, id); \
         base += 2; \
         stw_phys(as, base, \
-                 (sizeof(struct bi_record) + len + 3) & ~1); \
+                 (sizeof(struct bi_record) + len + \
+                  2 /* length field */ + 3 /* padding */) & ~3); \
         base += 2; \
         stw_phys(as, base, len); \
         base += 2; \
         for (i = 0; i < len; ++i) { \
             stb_phys(as, base++, data[i]); \
         } \
-        base = (base + 1) & ~1; \
+        base = (base + 3) & ~3; \
     } while (0)
 #endif