linux-kernel - [PATCH] riscv: require alternatives framework when selecting FPU support

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Message-Id: <20230322120907.2968494-1-Jason@zx2c4.com>
Date:   Wed, 22 Mar 2023 13:09:07 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Jisheng Zhang <jszhang@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Anup Patel <anup@...infault.org>,
        Atish Patra <atishp@...shpatra.org>,
        Heiko Stuebner <heiko@...ech.de>,
        Andrew Jones <ajones@...tanamicro.com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org,
        regressions@...mhuis.info, regressions@...ts.linux.dev
Cc:     "Jason A. Donenfeld" <Jason@...c4.com>
Subject: [PATCH] riscv: require alternatives framework when selecting FPU support

When moving switch_to's has_fpu() over to using riscv_has_extension_
likely() rather than static branchs, the FPU code gained a dependency on
the alternatives framework. If CONFIG_RISCV_ALTERNATIVE isn't selected
when CONFIG_FPU is, then has_fpu() returns false, and switch_to does not
work as intended. So select CONFIG_RISCV_ALTERNATIVE when CONFIG_FPU is
selected.

Fixes: 702e64550b12 ("riscv: fpu: switch has_fpu() to riscv_has_extension_likely()")
Link: https://lore.kernel.org/all/ZBruFRwt3rUVngPu@zx2c4.com/
Cc: Jisheng Zhang <jszhang@...nel.org>
Cc: Andrew Jones <ajones@...tanamicro.com>
Cc: Heiko Stuebner <heiko@...ech.de>
Cc: Conor Dooley <conor.dooley@...rochip.com>
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
 arch/riscv/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index c5e42cc37604..0f59350c699d 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -467,6 +467,7 @@ config TOOLCHAIN_HAS_ZIHINTPAUSE
 config FPU
 	bool "FPU support"
 	default y
+	select RISCV_ALTERNATIVE
 	help
 	  Say N here if you want to disable all floating-point related procedure
 	  in the kernel.
-- 
2.40.0