[STABLE BACKPORT v2 4.4.y, 4.9.y and 4.14.y] compiler.h: Raise minimum version of GCC to 5.1 for arm64

[Will Deacon]

commit dca5244d2f5b94f1809f0c02a549edf41ccd5493 upstream.

GCC versions >= 4.9 and < 5.1 have been shown to emit memory references
beyond the stack pointer, resulting in memory corruption if an interrupt
is taken after the stack pointer has been adjusted but before the
reference has been executed. This leads to subtle, infrequent data
corruption such as the EXT4 problems reported by Russell King at the
link below.

Life is too short for buggy compilers, so raise the minimum GCC version
required by arm64 to 5.1.

Reported-by: Russell King <linux@xxxxxxxxxxxxxxx>
Suggested-by: Arnd Bergmann <arnd@xxxxxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Tested-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 4.4.y, 4.9.y and 4.14.y only
Cc: Theodore Ts'o <tytso@xxxxxxx>
Cc: Florian Weimer <fweimer@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Nathan Chancellor <natechancellor@xxxxxxxxx>
Cc: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210105154726.GD1551@xxxxxxxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20210112224832.10980-1-will@xxxxxxxxxx
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
[will: backport to 4.4.y/4.9.y/4.14.y; add __clang__ check]
Link: https://lore.kernel.org/r/CA+G9fYuzE9WMSB7uGjV4gTzK510SHEdJb_UXQCzsQ5MqA=h9SA@xxxxxxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
 include/linux/compiler-gcc.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index af8b4a879934..9485abe76b68 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -145,6 +145,12 @@
 
 #if GCC_VERSION < 30200
 # error Sorry, your compiler is too old - please upgrade it.
+#elif defined(CONFIG_ARM64) && GCC_VERSION < 50100 && !defined(__clang__)
+/*
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293
+ * https://lore.kernel.org/r/20210107111841.GN1551@xxxxxxxxxxxxxxxxxxxxx
+ */
+# error Sorry, your version of GCC is too old - please use 5.1 or newer.
 #endif
 
 #if GCC_VERSION < 30300
-- 
2.30.0.280.ga3ce27912f-goog