From e9967889a09ba6b27eae030b34bfe4d223845119 Mon Sep 17 00:00:00 2001
From: KAAAsS <admin@kaaass.net>
Date: Thu, 21 Apr 2022 23:22:29 +0800
Subject: [PATCH] =?UTF-8?q?fix:=20cat=20=E6=8C=87=E4=BB=A4=E7=9A=84?=
 =?UTF-8?q?=E8=BE=93=E5=87=BA=E9=97=AE=E9=A2=98?=
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---
 lab5/user/lab5/apps/init.c | 2 --
 lab5/user/lib/string.c     | 5 +++++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/lab5/user/lab5/apps/init.c b/lab5/user/lab5/apps/init.c
index 7531246..34bf91c 100644
--- a/lab5/user/lab5/apps/init.c
+++ b/lab5/user/lab5/apps/init.c
@@ -453,8 +453,6 @@ int fs_read_all(char *path, void **ret_buf)
         if (cur < 0) {
             return cur;
         }
-        // FIXME: 此处在 Release 模式下第一次读取前 16 字节为空
-        memcpy(buf, (const void *) TMPFS_READ_BUF_VADDR, cur);
         memcpy(buf, (const void *) TMPFS_READ_BUF_VADDR, cur);
         pos += cur;
         buf += cur;
diff --git a/lab5/user/lib/string.c b/lab5/user/lib/string.c
index 5f4893a..3ce3240 100644
--- a/lab5/user/lib/string.c
+++ b/lab5/user/lib/string.c
@@ -12,6 +12,10 @@ void memset(void *dst, int c, u64 len)
 	}
 }
 
+// FIXME: 此处 workaround 用于避免 GCC 插入 SIMD 指令使用未被备份的寄存器导致程序问题
+// See also: https://ipads.se.sjtu.edu.cn/mospi/discussion/d/205-memcpy-gcc
+#pragma GCC push_options
+#pragma GCC optimize("O0")
 void memcpy(void *dst, const void *src, u64 len)
 {
 	u64 i = 0;
@@ -19,6 +23,7 @@ void memcpy(void *dst, const void *src, u64 len)
 		((u8 *) dst)[i] = ((u8 *) src)[i];
 	}
 }
+#pragma GCC pop_options
 
 int memcmp(const void *s1, const void *s2, size_t n)
 {