[PATCH 5.14 168/169] ARM: 9122/1: select HAVE_FUTEX_CMPXCHG

Greg Kroah-Hartman
2021-10-25T20:00:18Z

From: Nick Desaulniers <ndesaulniers@google.com>

commit 9d417cbe36eee7afdd85c2e871685f8dab7c2dba upstream.

tglx notes:
This function [futex_detect_cmpxchg] is only needed when an
architecture has to runtime discover whether the CPU supports it or
not. ARM has unconditional support for this, so the obvious thing to
do is the below.

Fixes linkage failure from Clang randconfigs:
kernel/futex.o:(.text.fixup+0x5c): relocation truncated to fit: R_ARM_JUMP24 against `.init.text'
and boot failures for CONFIG_THUMB2_KERNEL.

Link: https://github.com/ClangBuiltLinux/linux/issues/325

Comments from Nick Desaulniers:

See-also: 03b8c7b623c8 ("futex: Allow architectures to skip
futex_atomic_cmpxchg_inatomic() test")

Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Cc: stable@vger.kernel.org # v3.14+
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm/Kconfig | 1 +
1 file changed, 1 insertion(+)

--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -93,6 +93,7 @@ config ARM
select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
select HAVE_FUNCTION_GRAPH_TRACER if !THUMB2_KERNEL && !CC_IS_CLANG
select HAVE_FUNCTION_TRACER if !XIP_KERNEL
+ select HAVE_FUTEX_CMPXCHG if FUTEX
select HAVE_GCC_PLUGINS
select HAVE_HW_BREAKPOINT if PERF_EVENTS && (CPU_V6 || CPU_V6K || CPU_V7)
select HAVE_IRQ_TIME_ACCOUNTING