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From:   Mao Han <han_mao@c-sky.com>
To:     linux-kernel@vger.kernel.org
Cc:     linux-riscv@lists.infradead.org, linux-csky@vger.kernel.org,
        Mao Han <han_mao@c-sky.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>
Subject: [PATCH 1/1] riscv: Fix perf record without libelf support
Date:   Thu, 11 Jul 2019 10:38:40 +0800
Message-Id: <96b979a523210628de8a8a3d6e48492f6f1ff02d.1562812381.git.han_mao@c-sky.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

This patch fix following perf record error by linking vdso.so with
build id.

perf.data      perf.data.old
[ perf record: Woken up 1 times to write data ]
free(): double free detected in tcache 2
Aborted

perf record use filename__read_build_id(util/symbol-minimal.c) to get
build id when libelf is not supported. When vdso.so is linked without
build id, the section size of PT_NOTE will be zero, buf size will
realloc to zero and cause memory corruption.

Signed-off-by: Mao Han <han_mao@c-sky.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
---
 arch/riscv/kernel/vdso/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile
index f1d6ffe..49a5852 100644
--- a/arch/riscv/kernel/vdso/Makefile
+++ b/arch/riscv/kernel/vdso/Makefile
@@ -37,7 +37,7 @@ $(obj)/vdso.so.dbg: $(src)/vdso.lds $(obj-vdso) FORCE
 # these symbols in the kernel code rather than hand-coded addresses.
 
 SYSCFLAGS_vdso.so.dbg = -shared -s -Wl,-soname=linux-vdso.so.1 \
-	-Wl,--hash-style=both
+	-Wl,--build-id -Wl,--hash-style=both
 $(obj)/vdso-dummy.o: $(src)/vdso.lds $(obj)/rt_sigreturn.o FORCE
 	$(call if_changed,vdsold)
 
-- 
2.7.4