x86/boot/compressed: Avoid gcc-11 -Wstringop-overread warning

GCC gets confused by the comparison of a pointer to an integer literal,
with the assumption that this is an offset from a NULL pointer and that
dereferencing it is invalid:

  In file included from arch/x86/boot/compressed/misc.c:18:
  In function ‘parse_elf’,
      inlined from ‘extract_kernel’ at arch/x86/boot/compressed/misc.c:442:2:
  arch/x86/boot/compressed/../string.h:15:23: error: ‘__builtin_memcpy’ reading 64 bytes from a region of size 0 [-Werror=stringop-overread]
     15 | #define memcpy(d,s,l) __builtin_memcpy(d,s,l)
        |                       ^~~~~~~~~~~~~~~~~~~~~~~
  arch/x86/boot/compressed/misc.c:283:9: note: in expansion of macro ‘memcpy’
    283 |         memcpy(&ehdr, output, sizeof(ehdr));
        |         ^~~~~~

I could not find any good workaround for this, but as this is only
a warning for a failure during early boot, removing the line entirely
works around the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Sebor <msebor@gmail.com>
Link: https://lore.kernel.org/r/20210322160253.4032422-2-arnd@kernel.org

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 267e7f93050ef322cec5e29a742d685c6661b75c..1945b8a0cad85c8be0f87659b323f4f2d35fe16f 100644 (file)
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -430,8 +430,6 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
                error("Destination address too large");
 #endif
 #ifndef CONFIG_RELOCATABLE
-       if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
-               error("Destination address does not match LOAD_PHYSICAL_ADDR");
        if (virt_addr != LOAD_PHYSICAL_ADDR)
                error("Destination virtual address changed when not relocatable");
 #endif