linux-kernel - [PATCH 1/2] ARM: Refactor dump

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Date:   Mon, 28 Nov 2022 19:42:42 +0800
From:   Zhen Lei <thunder.leizhen@...wei.com>
To:     Russell King <linux@...linux.org.uk>,
        Ard Biesheuvel <ardb@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <patches@...linux.org.uk>
CC:     Zhen Lei <thunder.leizhen@...wei.com>
Subject: [PATCH 1/2] ARM: Refactor dump_instr()

1. Rename local variable 'val16' to 'tmp'. So that the processing
   statements of thumb and arm can be aligned.
2. Fix two sparse check warnings: (add __user for type conversion)
   warning: incorrect type in initializer (different address spaces)
      expected unsigned short [noderef] __user *register __p
      got unsigned short [usertype] *
3. Prepare for the next patch to avoid repeated judgment.
   Before:
   if (!user_mode(regs)) {
           if (thumb)
           else
   } else {
           if (thumb)
           else
   }

   After:
   if (thumb) {
           if (user_mode(regs))
           else
   } else {
           if (user_mode(regs))
           else
   }

Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
---
KernelVersion: v6.1-rc7
 arch/arm/kernel/traps.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 20b2db6dcd1ced7..a92e0763739584e 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -178,19 +178,20 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
 	for (i = -4; i < 1 + !!thumb; i++) {
 		unsigned int val, bad;
 
-		if (!user_mode(regs)) {
-			if (thumb) {
-				u16 val16;
-				bad = get_kernel_nofault(val16, &((u16 *)addr)[i]);
-				val = val16;
-			} else {
-				bad = get_kernel_nofault(val, &((u32 *)addr)[i]);
-			}
+		if (thumb) {
+			u16 tmp;
+
+			if (user_mode(regs))
+				bad = get_user(tmp, &((u16 __user *)addr)[i]);
+			else
+				bad = get_kernel_nofault(tmp, &((u16 *)addr)[i]);
+
+			val = tmp;
 		} else {
-			if (thumb)
-				bad = get_user(val, &((u16 *)addr)[i]);
+			if (user_mode(regs))
+				bad = get_user(val, &((u32 __user *)addr)[i]);
 			else
-				bad = get_user(val, &((u32 *)addr)[i]);
+				bad = get_kernel_nofault(val, &((u32 *)addr)[i]);
 		}
 
 		if (!bad)
-- 
2.25.1