diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0041-nospec-Allow-index-argument-to-have-const-qualified-.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0041-nospec-Allow-index-argument-to-have-const-qualified-.patch | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0041-nospec-Allow-index-argument-to-have-const-qualified-.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0041-nospec-Allow-index-argument-to-have-const-qualified-.patch new file mode 100644 index 00000000..48dd7bd7 --- /dev/null +++ b/common/recipes-kernel/linux/linux-yocto-4.9.21/0041-nospec-Allow-index-argument-to-have-const-qualified-.patch @@ -0,0 +1,68 @@ +From 0f31ea4b42fd0a593d539e2278b1baa35a31a122 Mon Sep 17 00:00:00 2001 +From: Rasmus Villemoes <linux@rasmusvillemoes.dk> +Date: Fri, 16 Feb 2018 13:20:48 -0800 +Subject: [PATCH 41/93] nospec: Allow index argument to have const-qualified + type + +commit b98c6a160a057d5686a8c54c79cc6c8c94a7d0c8 upstream. + +The last expression in a statement expression need not be a bare +variable, quoting gcc docs + + The last thing in the compound statement should be an expression + followed by a semicolon; the value of this subexpression serves as the + value of the entire construct. + +and we already use that in e.g. the min/max macros which end with a +ternary expression. + +This way, we can allow index to have const-qualified type, which will in +some cases avoid the need for introducing a local copy of index of +non-const qualified type. That, in turn, can prevent readers not +familiar with the internals of array_index_nospec from wondering about +the seemingly redundant extra variable, and I think that's worthwhile +considering how confusing the whole _nospec business is. + +The expression _i&_mask has type unsigned long (since that is the type +of _mask, and the BUILD_BUG_ONs guarantee that _i will get promoted to +that), so in order not to change the type of the whole expression, add +a cast back to typeof(_i). + +Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> +Signed-off-by: Dan Williams <dan.j.williams@intel.com> +Acked-by: Linus Torvalds <torvalds@linux-foundation.org> +Cc: Andy Lutomirski <luto@kernel.org> +Cc: Arjan van de Ven <arjan@linux.intel.com> +Cc: Borislav Petkov <bp@alien8.de> +Cc: Dave Hansen <dave.hansen@linux.intel.com> +Cc: David Woodhouse <dwmw2@infradead.org> +Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +Cc: Josh Poimboeuf <jpoimboe@redhat.com> +Cc: Peter Zijlstra <peterz@infradead.org> +Cc: Thomas Gleixner <tglx@linutronix.de> +Cc: Will Deacon <will.deacon@arm.com> +Cc: linux-arch@vger.kernel.org +Cc: stable@vger.kernel.org +Link: http://lkml.kernel.org/r/151881604837.17395.10812767547837568328.stgit@dwillia2-desk3.amr.corp.intel.com +Signed-off-by: Ingo Molnar <mingo@kernel.org> +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +--- + include/linux/nospec.h | 3 +-- + 1 file changed, 1 insertion(+), 2 deletions(-) + +diff --git a/include/linux/nospec.h b/include/linux/nospec.h +index fbc98e2..132e3f5 100644 +--- a/include/linux/nospec.h ++++ b/include/linux/nospec.h +@@ -72,7 +72,6 @@ static inline unsigned long array_index_mask_nospec(unsigned long index, + BUILD_BUG_ON(sizeof(_i) > sizeof(long)); \ + BUILD_BUG_ON(sizeof(_s) > sizeof(long)); \ + \ +- _i &= _mask; \ +- _i; \ ++ (typeof(_i)) (_i & _mask); \ + }) + #endif /* _LINUX_NOSPEC_H */ +-- +2.7.4 + |