linux-kernel - [PATCH] m68k: use get_kernel_nofault in show

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Message-Id: <20200720114314.196686-1-hch@lst.de>
Date:   Mon, 20 Jul 2020 13:43:14 +0200
From:   Christoph Hellwig <hch@....de>
To:     geert@...ux-m68k.org
Cc:     linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org
Subject: [PATCH] m68k: use get_kernel_nofault in show_registers

Use the proper get_kernel_nofault helper to access an unsafe kernel
pointer without faulting instead of playing with set_fs and get_user.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 arch/m68k/kernel/traps.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index df6fc782754f73..c265355fa244d4 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -846,7 +846,6 @@ static void show_trace(unsigned long *stack, const char *loglvl)
 void show_registers(struct pt_regs *regs)
 {
 	struct frame *fp = (struct frame *)regs;
-	mm_segment_t old_fs = get_fs();
 	u16 c, *cp;
 	unsigned long addr;
 	int i;
@@ -919,10 +918,9 @@ void show_registers(struct pt_regs *regs)
 	show_stack(NULL, (unsigned long *)addr, KERN_INFO);
 
 	pr_info("Code:");
-	set_fs(KERNEL_DS);
 	cp = (u16 *)regs->pc;
 	for (i = -8; i < 16; i++) {
-		if (get_user(c, cp + i) && i >= 0) {
+		if (get_kernel_nofault(c, cp + i) && i >= 0) {
 			pr_cont(" Bad PC value.");
 			break;
 		}
@@ -931,7 +929,6 @@ void show_registers(struct pt_regs *regs)
 		else
 			pr_cont(" <%04x>", c);
 	}
-	set_fs(old_fs);
 	pr_cont("\n");
 }
 
-- 
2.27.0