Commit 3a24a608 authored by Brian Gerst's avatar Brian Gerst Committed by Borislav Petkov
Browse files

x86/32: Remove lazy GS macros 



GS is always a user segment now.

Signed-off-by: default avatarBrian Gerst <brgerst@gmail.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20220325153953.162643-4-brgerst@gmail.com
parent 9554e908

arch/x86/include/asm/mmu_context.h

+1 −1
Original line number Diff line number Diff line
@@ -141,7 +141,7 @@ do { \ 
#ifdef CONFIG_X86_32

#define deactivate_mm(tsk, mm)			\

do {						\

	lazy_load_gs(0);			\

	loadsegment(gs, 0);			\

} while (0)

#else

#define deactivate_mm(tsk, mm)			\

arch/x86/include/asm/segment.h

+0 −5
Original line number Diff line number Diff line
@@ -354,11 +354,6 @@ static inline void __loadsegment_fs(unsigned short value) 
 * x86-32 user GS accessors.  This is ugly and could do with some cleaning up.

 */

#ifdef CONFIG_X86_32

# define get_user_gs(regs)		(u16)({ unsigned long v; savesegment(gs, v); v; })

# define set_user_gs(regs, v)		loadsegment(gs, (unsigned long)(v))

# define task_user_gs(tsk)		((tsk)->thread.gs)

# define lazy_save_gs(v)		savesegment(gs, (v))

# define lazy_load_gs(v)		loadsegment(gs, (v))

# define load_gs_index(v)		loadsegment(gs, (v))

#endif	/* X86_32 */

arch/x86/kernel/process.c

+1 −4
Original line number Diff line number Diff line
@@ -160,6 +160,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, 
	savesegment(ds, p->thread.ds);

#else

	p->thread.sp0 = (unsigned long) (childregs + 1);

	savesegment(gs, p->thread.gs);

	/*

	 * Clear all status flags including IF and set fixed bit. 64bit

	 * does not have this initialization as the frame does not contain
@@ -191,10 +192,6 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, 
	if (sp)

		childregs->sp = sp;



#ifdef CONFIG_X86_32

	task_user_gs(p) = get_user_gs(current_pt_regs());

#endif



	if (unlikely(p->flags & PF_IO_WORKER)) {

		/*

		 * An IO thread is a user space thread, but it doesn't

arch/x86/kernel/process_32.c

+4 −7
Original line number Diff line number Diff line
@@ -63,9 +63,6 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, 
	unsigned long d0, d1, d2, d3, d6, d7;

	unsigned short gs;



	if (user_mode(regs))

		gs = get_user_gs(regs);

	else

	savesegment(gs, gs);



	show_ip(regs, log_lvl);
@@ -114,7 +111,7 @@ void release_thread(struct task_struct *dead_task) 
void

start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)

{

	set_user_gs(regs, 0);

	loadsegment(gs, 0);

	regs->fs		= 0;

	regs->ds		= __USER_DS;

	regs->es		= __USER_DS;
@@ -177,7 +174,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) 
	 * used %fs or %gs (it does not today), or if the kernel is

	 * running inside of a hypervisor layer.

	 */

	lazy_save_gs(prev->gs);

	savesegment(gs, prev->gs);



	/*

	 * Load the per-thread Thread-Local Storage descriptor.
@@ -208,7 +205,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) 
	 * Restore %gs if needed (which is common)

	 */

	if (prev->gs | next->gs)

		lazy_load_gs(next->gs);

		loadsegment(gs, next->gs);



	this_cpu_write(current_task, next_p);

arch/x86/kernel/ptrace.c

+3 −3
Original line number Diff line number Diff line
@@ -170,9 +170,9 @@ static u16 get_segment_reg(struct task_struct *task, unsigned long offset) 
		retval = *pt_regs_access(task_pt_regs(task), offset);

	else {

		if (task == current)

			retval = get_user_gs(task_pt_regs(task));

			savesegment(gs, retval);

		else

			retval = task_user_gs(task);

			retval = task->thread.gs;

	}

	return retval;

}
@@ -210,7 +210,7 @@ static int set_segment_reg(struct task_struct *task, 
		break;



	case offsetof(struct user_regs_struct, gs):

		task_user_gs(task) = value;

		task->thread.gs = value;

	}



	return 0;