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| author | Sasha Levin <sashal@kernel.org> | 2019-06-28 16:36:14 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-03 13:15:59 +0200 |
| commit | c6975e4196549c18c5277a55e30b2d6d1b80abf2 (patch) | |
| tree | 0980b801b15e808f631dbb678ba291202efaa9d3 | |
| parent | 5267bb9c170d2b99e3cfdb8b60704e375e942266 (diff) | |
| download | linux-stable-c6975e4196549c18c5277a55e30b2d6d1b80abf2.tar.gz linux-stable-c6975e4196549c18c5277a55e30b2d6d1b80abf2.tar.bz2 linux-stable-c6975e4196549c18c5277a55e30b2d6d1b80abf2.zip | |
Revert "compiler.h: update definition of unreachable()"
This reverts commit 82017e26e51596ee577171a33f357377ec6513b5, which is
upstream commit fe0640eb30b7da261ae84d252ed9ed3c7e68dfd8.
On Fri, Jun 28, 2019 at 8:53 AM Tony Battersby <tonyb@cybernetics.com> wrote:
>
> Old versions of gcc cannot compile 4.14 since 4.14.113:
>
> ./include/asm-generic/fixmap.h:37: error: implicit declaration of function ‘__builtin_unreachable’
>
> The stable commit that caused the problem is 82017e26e515 ("compiler.h:
> update definition of unreachable()") (upstream commit fe0640eb30b7).
> Reverting the commit fixes the problem.
>
> Kernel 4.17 dropped support for older versions of gcc in upstream commit
> cafa0010cd51 ("Raise the minimum required gcc version to 4.6"). This
> was not backported to 4.14 since that would go against the stable kernel
> rules.
>
> Upstream commit 815f0ddb346c ("include/linux/compiler*.h: make
> compiler-*.h mutually exclusive") was a fix for cafa0010cd51. This was
> not backported to 4.14.
>
> Upstream commit fe0640eb30b7 ("compiler.h: update definition of
> unreachable()") was a fix for 815f0ddb346c. This is the commit that was
> backported to 4.14. But it only fixed a problem introduced in the other
> commits, and without those commits, it ends up introducing a problem
> instead of fixing one. So I recommend reverting that patch in 4.14,
> which will enable old gcc to compile 4.14 again. If I understand
> correctly, I believe that clang will still be able to compile 4.14 with
> the patch reverted, although I haven't tried to compile with clang.
>
> The problematic commit is not present in 4.9.x, 4.4.x, 3.18.x, or 3.16.x.
CC: Nick Desaulniers <ndesaulniers@google.com>
CC: Tony Battersby <tonyb@cybernetics.com>,
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | include/linux/compiler.h | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 67c3934fb9ed..a704d032713b 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -119,10 +119,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, # define ASM_UNREACHABLE #endif #ifndef unreachable -# define unreachable() do { \ - annotate_unreachable(); \ - __builtin_unreachable(); \ -} while (0) +# define unreachable() do { annotate_reachable(); do { } while (1); } while (0) #endif /* |