x86/asm/32: Remove a bunch of '& 0xffff' from pt_regs segment reads

Now that pt_regs properly defines segment fields as 16-bit on 32-bit
CPUs, there's no need to mask off the high word.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

arch/x86/ia32/ia32_signal.c

@@ -226,7 +226,7 @@ static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
 	if (ksig->ka.sa.sa_flags & SA_ONSTACK)
 		sp = sigsp(sp, ksig);
 	/* This is the legacy signal stack switching. */
-	else if ((regs->ss & 0xffff) != __USER32_DS &&
+	else if (regs->ss != __USER32_DS &&
 		!(ksig->ka.sa.sa_flags & SA_RESTORER) &&
 		 ksig->ka.sa.sa_restorer)
 		sp = (unsigned long) ksig->ka.sa.sa_restorer;

arch/x86/include/asm/elf.h

@@ -126,15 +126,15 @@ do {						\
 	pr_reg[4] = regs->di;			\
 	pr_reg[5] = regs->bp;			\
 	pr_reg[6] = regs->ax;			\
-	pr_reg[7] = regs->ds & 0xffff;		\
-	pr_reg[8] = regs->es & 0xffff;		\
-	pr_reg[9] = regs->fs & 0xffff;		\
+	pr_reg[7] = regs->ds;			\
+	pr_reg[8] = regs->es;			\
+	pr_reg[9] = regs->fs;			\
 	pr_reg[11] = regs->orig_ax;		\
 	pr_reg[12] = regs->ip;			\
-	pr_reg[13] = regs->cs & 0xffff;		\
+	pr_reg[13] = regs->cs;			\
 	pr_reg[14] = regs->flags;		\
 	pr_reg[15] = regs->sp;			\
-	pr_reg[16] = regs->ss & 0xffff;		\
+	pr_reg[16] = regs->ss;			\
 } while (0);
 
 #define ELF_CORE_COPY_REGS(pr_reg, regs)	\

arch/x86/kernel/dumpstack.c

@@ -267,7 +267,7 @@ int __die(const char *str, struct pt_regs *regs, long err)
 #ifdef CONFIG_X86_32
 	if (user_mode(regs)) {
 		sp = regs->sp;
-		ss = regs->ss & 0xffff;
+		ss = regs->ss;
 	} else {
 		sp = kernel_stack_pointer(regs);
 		savesegment(ss, ss);

arch/x86/kernel/process_32.c

@@ -68,7 +68,7 @@ void __show_regs(struct pt_regs *regs, int all)
 
 	if (user_mode(regs)) {
 		sp = regs->sp;
-		ss = regs->ss & 0xffff;
+		ss = regs->ss;
 		gs = get_user_gs(regs);
 	} else {
 		sp = kernel_stack_pointer(regs);

arch/x86/kernel/process_64.c

@@ -69,8 +69,7 @@ void __show_regs(struct pt_regs *regs, int all)
 	unsigned int fsindex, gsindex;
 	unsigned int ds, cs, es;
 
-	printk(KERN_DEFAULT "RIP: %04lx:%pS\n", regs->cs & 0xffff,
-		(void *)regs->ip);
+	printk(KERN_DEFAULT "RIP: %04lx:%pS\n", regs->cs, (void *)regs->ip);
 	printk(KERN_DEFAULT "RSP: %04lx:%016lx EFLAGS: %08lx", regs->ss,
 		regs->sp, regs->flags);
 	if (regs->orig_ax != -1)

arch/x86/kernel/signal.c

@@ -256,7 +256,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 			sp = current->sas_ss_sp + current->sas_ss_size;
 	} else if (IS_ENABLED(CONFIG_X86_32) &&
 		   !onsigstack &&
-		   (regs->ss & 0xffff) != __USER_DS &&
+		   regs->ss != __USER_DS &&
 		   !(ka->sa.sa_flags & SA_RESTORER) &&
 		   ka->sa.sa_restorer) {
 		/* This is the legacy signal stack switching. */

arch/x86/kernel/step.c

@@ -13,7 +13,7 @@ unsigned long convert_ip_to_linear(struct task_struct *child, struct pt_regs *re
 	unsigned long addr, seg;
 
 	addr = regs->ip;
-	seg = regs->cs & 0xffff;
+	seg = regs->cs;
 	if (v8086_mode(regs)) {
 		addr = (addr & 0xffff) + (seg << 4);
 		return addr;

arch/x86/mm/extable.c

@@ -142,7 +142,7 @@ void __init early_fixup_exception(struct pt_regs *regs, int trapnr)
 	 * undefined.  I'm not sure which CPUs do this, but at least
 	 * the 486 DX works this way.
 	 */
-	if ((regs->cs & 0xFFFF) != __KERNEL_CS)
+	if (regs->cs != __KERNEL_CS)
 		goto fail;
 
 	/*