linux-kernel - [PATCH] riscv: force __cpu_up_ variables to put in data section

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Message-Id: <20200430095325.111441-1-zong.li@sifive.com>
Date:   Thu, 30 Apr 2020 17:53:25 +0800
From:   Zong Li <zong.li@...ive.com>
To:     paul.walmsley@...ive.com, palmer@...belt.com,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Zong Li <zong.li@...ive.com>
Subject: [PATCH] riscv: force __cpu_up_ variables to put in data section

Put __cpu_up_stack_pointer and __cpu_up_task_pointer in data section.
Currently, these two variables are put in bss section, there is a
potential risk that secondary harts get the uninitialized value before
main hart finishing the bss clearing. In this case, all secondary
harts would go through the waiting loop and enable the MMU before
main hart set up the page table.

Signed-off-by: Zong Li <zong.li@...ive.com>
---
 arch/riscv/kernel/cpu_ops.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/cpu_ops.c b/arch/riscv/kernel/cpu_ops.c
index c4c33bf02369..0ec22354018c 100644
--- a/arch/riscv/kernel/cpu_ops.c
+++ b/arch/riscv/kernel/cpu_ops.c
@@ -15,8 +15,8 @@
 
 const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
 
-void *__cpu_up_stack_pointer[NR_CPUS];
-void *__cpu_up_task_pointer[NR_CPUS];
+void *__cpu_up_stack_pointer[NR_CPUS] __section(.data);
+void *__cpu_up_task_pointer[NR_CPUS] __section(.data);
 
 extern const struct cpu_operations cpu_ops_sbi;
 extern const struct cpu_operations cpu_ops_spinwait;
-- 
2.26.1