linux-kernel - [PATCH] LoongArch: Fix missing fcsr in ptrace's fpr

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Date:   Thu, 14 Jul 2022 14:25:50 +0800
From:   Qi Hu <huqi@...ngson.cn>
To:     Huacai Chen <chenhuacai@...nel.org>,
        WANG Xuerui <kernel@...0n.name>,
        Oleg Nesterov <oleg@...hat.com>
Cc:     Xu Li <lixu@...ngson.cn>, loongarch@...ts.linux.dev,
        LKML <linux-kernel@...r.kernel.org>, Qi Hu <huqi@...ngson.cn>
Subject: [PATCH] LoongArch: Fix missing fcsr in ptrace's fpr_set

In file ptrace.c, function fpr_set does not copy fcsr data from ubuf
to kbuf. That's the reason why fcsr cannot be modified by ptrace.

This patch fixs this problem and allows users using ptrace to modify
the fcsr.

Signed-off-by: Qi Hu <huqi@...ngson.cn>
Signed-off-by: Xu Li <lixu@...ngson.cn>
---
 arch/loongarch/kernel/ptrace.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/loongarch/kernel/ptrace.c b/arch/loongarch/kernel/ptrace.c
index e6ab87948e1d..dc2b82ea894c 100644
--- a/arch/loongarch/kernel/ptrace.c
+++ b/arch/loongarch/kernel/ptrace.c
@@ -193,7 +193,7 @@ static int fpr_set(struct task_struct *target,
 		   const void *kbuf, const void __user *ubuf)
 {
 	const int fcc_start = NUM_FPU_REGS * sizeof(elf_fpreg_t);
-	const int fcc_end = fcc_start + sizeof(u64);
+	const int fcsr_start = fcc_start + sizeof(u64);
 	int err;
 
 	BUG_ON(count % sizeof(elf_fpreg_t));
@@ -209,10 +209,12 @@ static int fpr_set(struct task_struct *target,
 	if (err)
 		return err;
 
-	if (count > 0)
-		err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
-					  &target->thread.fpu.fcc,
-					  fcc_start, fcc_end);
+	err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				  &target->thread.fpu.fcc, fcc_start,
+				  fcc_start + sizeof(u64));
+	err |= user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				  &target->thread.fpu.fcsr, fcsr_start,
+				  fcsr_start + sizeof(u32));
 
 	return err;
 }
-- 
2.37.0