linux-kernel - [PATCH v2 1/2] riscv: vdso: Prevent gcc from inserting calls to memset()

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Message-Id: <20240705060902.113294-2-alexghiti@rivosinc.com>
Date: Fri,  5 Jul 2024 08:09:01 +0200
From: Alexandre Ghiti <alexghiti@...osinc.com>
To: Vladimir Isaev <vladimir.isaev@...tacore.com>,
	Roman Artemev <roman.artemev@...tacore.com>,
	Guo Ren <guoren@...nel.org>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc: Alexandre Ghiti <alexghiti@...osinc.com>
Subject: [PATCH v2 1/2] riscv: vdso: Prevent gcc from inserting calls to memset()

gcc is smart enough to insert a call to memset() in
riscv_vdso_get_cpus(), which generates a dynamic relocation.

So prevent gcc from doing that by using the
-fno-tree-loop-distribute-patterns option.

Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
---
 arch/riscv/kernel/vdso/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile
index f7ef8ad9b550..c7e40bf36371 100644
--- a/arch/riscv/kernel/vdso/Makefile
+++ b/arch/riscv/kernel/vdso/Makefile
@@ -18,6 +18,7 @@ obj-vdso = $(patsubst %, %.o, $(vdso-syms)) note.o
 
 ccflags-y := -fno-stack-protector
 ccflags-y += -DDISABLE_BRANCH_PROFILING
+ccflags-y += -fno-tree-loop-distribute-patterns
 
 ifneq ($(c-gettimeofday-y),)
   CFLAGS_vgettimeofday.o += -fPIC -include $(c-gettimeofday-y)
-- 
2.39.2