Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Tue, 8 Dec 2015 15:59:14 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH v4 3/3] UBSAN: run-time undefined behavior sanity checker |
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On Thu, 3 Dec 2015 18:50:07 +0300 Andrey Ryabinin <aryabinin@virtuozzo.com> wrote:
> UBSAN uses compile-time instrumentation to catch undefined behavior (UB). > Compiler inserts code that perform certain kinds of checks before > operations that could cause UB. If check fails (i.e. UB detected) > __ubsan_handle_* function called to print error message. > > So the most of the work is done by compiler. This patch just > implements ubsan handlers printing errors. > > GCC has this capability since 4.9.x [1] (see -fsanitize=undefined > option and its suboptions). > However GCC 5.x has more checkers implemented [2]. > Article [3] has a bit more details about UBSAN in the GCC. > > ... > > +#ifdef CONFIG_ARCH_SUPPORTS_INT128 > +typedef __int128 s_max; > +typedef unsigned __int128 u_max; > +#else
In file included from lib/ubsan.c:21: lib/ubsan.h:77: error: expected '=', ',', ';', 'asm' or '__attribute__' before 's_max' lib/ubsan.h:78: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'u_max' lib/ubsan.c:89: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'get_signed_val'
gcc-4.4.4 doesn't appear to like __int128. The only other use of __int128 is include/linux/math64.h:mul_u64_u32_shr() and it uses defined(__SIZEOF_INT128__) as well.
Using that gives me
lib/ubsan.c: In function 'val_to_string': lib/ubsan.c:127: warning: right shift count >= width of type lib/ubsan.c:128: warning: right shift count >= width of type
so I bodged that site too. I need to get an mmotm release out the door.
--- a/lib/ubsan.c~ubsan-run-time-undefined-behavior-sanity-checker-fix-3 +++ a/lib/ubsan.c @@ -120,7 +120,7 @@ static void val_to_string(char *str, siz { if (type_is_int(type)) { if (type_bit_width(type) == 128) { -#ifdef CONFIG_ARCH_SUPPORTS_INT128 +#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__) u_max val = get_unsigned_val(type, value); scnprintf(str, size, "0x%08x%08x%08x%08x", --- a/lib/ubsan.h~ubsan-run-time-undefined-behavior-sanity-checker-fix-3 +++ a/lib/ubsan.h @@ -73,7 +73,7 @@ struct invalid_value_data { struct type_descriptor *type; }; -#ifdef CONFIG_ARCH_SUPPORTS_INT128 +#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__) typedef __int128 s_max; typedef unsigned __int128 u_max; #else _
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