[tip: x86/core] x86/32: Remove lazy GS macros

From: tip-bot2 for Brian Gerst
Date: Fri Apr 15 2022 - 05:42:36 EST

The following commit has been merged into the x86/core branch of tip:

Commit-ID: 3a24a60854d2ef19e0edcd11cdbbb4fabc655dde
Gitweb: https://git.kernel.org/tip/3a24a60854d2ef19e0edcd11cdbbb4fabc655dde
Author: Brian Gerst <brgerst@xxxxxxxxx>
AuthorDate: Fri, 25 Mar 2022 11:39:52 -04:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Thu, 14 Apr 2022 14:09:43 +02:00

x86/32: Remove lazy GS macros

GS is always a user segment now.

Signed-off-by: Brian Gerst <brgerst@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220325153953.162643-4-brgerst@xxxxxxxxx
---
arch/x86/include/asm/mmu_context.h | 2 +-
arch/x86/include/asm/segment.h | 5 -----
arch/x86/kernel/process.c | 5 +----
arch/x86/kernel/process_32.c | 11 ++++-------
arch/x86/kernel/ptrace.c | 6 +++---
arch/x86/kernel/signal.c | 8 +++++---
arch/x86/kernel/vm86_32.c | 4 ++--
arch/x86/lib/insn-eval.c | 5 +++--
arch/x86/math-emu/get_address.c | 2 +-
9 files changed, 20 insertions(+), 28 deletions(-)

diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 2751604..b8d40dd 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -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) \
diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
index 656ed65..617b366 100644
--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -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 */

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index b370767..96a9885 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -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
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 26edb1c..877358f 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -63,10 +63,7 @@ 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);
+ 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);

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 98d10ef..37c12fb 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -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;
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index e439eb1..9c7265b 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -93,7 +93,7 @@ static bool restore_sigcontext(struct pt_regs *regs,
return false;

#ifdef CONFIG_X86_32
- set_user_gs(regs, sc.gs);
+ loadsegment(gs, sc.gs);
regs->fs = sc.fs;
regs->es = sc.es;
regs->ds = sc.ds;
@@ -146,8 +146,10 @@ __unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
struct pt_regs *regs, unsigned long mask)
{
#ifdef CONFIG_X86_32
- unsafe_put_user(get_user_gs(regs),
- (unsigned int __user *)&sc->gs, Efault);
+ unsigned int gs;
+ savesegment(gs, gs);
+
+ unsafe_put_user(gs, (unsigned int __user *)&sc->gs, Efault);
unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault);
unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault);
unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault);
diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index c21bcd6..e9e803a 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -151,7 +151,7 @@ exit_vm86:

memcpy(&regs->pt, &vm86->regs32, sizeof(struct pt_regs));

- lazy_load_gs(vm86->regs32.gs);
+ loadsegment(gs, vm86->regs32.gs);

regs->pt.ax = retval;
return;
@@ -325,7 +325,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus)
* Save old state
*/
vm86->saved_sp0 = tsk->thread.sp0;
- lazy_save_gs(vm86->regs32.gs);
+ savesegment(gs, vm86->regs32.gs);

/* make room for real-mode segments */
preempt_disable();
diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
index b781d32..21104c4 100644
--- a/arch/x86/lib/insn-eval.c
+++ b/arch/x86/lib/insn-eval.c
@@ -342,9 +342,9 @@ static int resolve_seg_reg(struct insn *insn, struct pt_regs *regs, int regoff)
*/
static short get_segment_selector(struct pt_regs *regs, int seg_reg_idx)
{
-#ifdef CONFIG_X86_64
unsigned short sel;

+#ifdef CONFIG_X86_64
switch (seg_reg_idx) {
case INAT_SEG_REG_IGNORE:
return 0;
@@ -402,7 +402,8 @@ static short get_segment_selector(struct pt_regs *regs, int seg_reg_idx)
case INAT_SEG_REG_FS:
return (unsigned short)(regs->fs & 0xffff);
case INAT_SEG_REG_GS:
- return get_user_gs(regs);
+ savesegment(gs, sel);
+ return sel;
case INAT_SEG_REG_IGNORE:
default:
return -EINVAL;
diff --git a/arch/x86/math-emu/get_address.c b/arch/x86/math-emu/get_address.c
index b82ca14..4a9fd90 100644
--- a/arch/x86/math-emu/get_address.c
+++ b/arch/x86/math-emu/get_address.c
@@ -153,7 +153,7 @@ static long pm_address(u_char FPU_modrm, u_char segment,
switch (segment) {
case PREFIX_GS_ - 1:
/* user gs handling can be lazy, use special accessors */
- addr->selector = get_user_gs(FPU_info->regs);
+ savesegment(gs, addr->selector);
break;
default:
addr->selector = PM_REG_(segment);