linux-kernel - [PATCH v4] MIPS: adding a safety check for cpu_has

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Date:   Mon,  2 May 2022 11:20:02 +0800
From:   Stephen Zhang <starzhangzsd@...il.com>
To:     macro@...am.me.uk, tsbogend@...ha.franken.de,
        liam.howlett@...cle.com, geert@...ux-m68k.org,
        ebiederm@...ssion.com, dbueso@...e.de, alobakin@...me,
        f.fainelli@...il.com, paul@...pouillou.net, linux@...ck-us.net,
        anemo@....ocn.ne.jp
Cc:     zhangshida@...inos.cn, starzhangzsd@...il.com,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org
Subject: [PATCH v4] MIPS: adding a safety check for cpu_has_fpu

From: Shida Zhang <zhangshida@...inos.cn>

There is a chance 'cpu_has_fpu' would still be overridden when the
CONFIG_MIPS_FP_SUPPORT configuration option has been disabled. So
add a safety check for 'cpu_has_fpu'.

Suggested-by: Maciej W. Rozycki <macro@...am.me.uk>
Signed-off-by: Shida Zhang <zhangshida@...inos.cn>
---
 Changelog in v1 -> v2:
 - Choose to redefine cpu_has_fpu to solve the problem silently.

 Changelog in v2 -> v3:
 - Choose to point out the error instead.

 Changelog in v3 -> v4:
 - Make the check work for 'nofpu' option.

 arch/mips/include/asm/cpu-features.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h
index de8cb2ccb781..c0983130a44c 100644
--- a/arch/mips/include/asm/cpu-features.h
+++ b/arch/mips/include/asm/cpu-features.h
@@ -133,6 +133,9 @@
 #  define raw_cpu_has_fpu	0
 # endif
 #else
+# if cpu_has_fpu
+#  error "Forcing `cpu_has_fpu' to non-zero is not supported"
+# endif
 # define raw_cpu_has_fpu	cpu_has_fpu
 #endif
 #ifndef cpu_has_32fpr
-- 
2.30.2