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x86/process: Unify copy_thread_tls() 

While looking at the TSS io bitmap it turned out that any change in that
area would require identical changes to copy_thread_tls(). The 32 and 64
bit variants share sufficient code to consolidate them into a common
function to avoid duplication of upcoming modifications.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
This commit is contained in:
Thomas Gleixner 2019-11-11 23:03:16 +01:00
parent 8c40397f22
commit 2fff071d28
5 changed files with 116 additions and 143 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/include/asm/ptrace.h
View File

@ -361,5 +361,11 @@ extern int do_get_thread_area(struct task_struct *p, int idx,
extern int do_set_thread_area(struct task_struct *p, int idx,
struct user_desc __user *info, int can_allocate);
#ifdef CONFIG_X86_64
# define do_set_thread_area_64(p, s, t) do_arch_prctl_64(p, s, t)
#else
# define do_set_thread_area_64(p, s, t) (0)
#endif
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_X86_PTRACE_H */

10
arch/x86/include/asm/switch_to.h
View File

@ -103,7 +103,17 @@ static inline void update_task_stack(struct task_struct *task)
if (static_cpu_has(X86_FEATURE_XENPV))
load_sp0(task_top_of_stack(task));
#endif
}
static inline void kthread_frame_init(struct inactive_task_frame *frame,
unsigned long fun, unsigned long arg)
{
frame->bx = fun;
#ifdef CONFIG_X86_32
frame->di = arg;
#else
frame->r12 = arg;
#endif
}
#endif /* _ASM_X86_SWITCH_TO_H */

100
arch/x86/kernel/process.c
View File

@ -132,6 +132,106 @@ void exit_thread(struct task_struct *tsk)
fpu__drop(fpu);
}
static int set_new_tls(struct task_struct *p, unsigned long tls)
{
struct user_desc __user *utls = (struct user_desc __user *)tls;
if (in_ia32_syscall())
return do_set_thread_area(p, -1, utls, 0);
else
return do_set_thread_area_64(p, ARCH_SET_FS, tls);
}
static inline int copy_io_bitmap(struct task_struct *tsk)
{
if (likely(!test_tsk_thread_flag(current, TIF_IO_BITMAP)))
return 0;
tsk->thread.io_bitmap_ptr = kmemdup(current->thread.io_bitmap_ptr,
IO_BITMAP_BYTES, GFP_KERNEL);
if (!tsk->thread.io_bitmap_ptr) {
tsk->thread.io_bitmap_max = 0;
return -ENOMEM;
}
set_tsk_thread_flag(tsk, TIF_IO_BITMAP);
return 0;
}
static inline void free_io_bitmap(struct task_struct *tsk)
{
if (tsk->thread.io_bitmap_ptr) {
kfree(tsk->thread.io_bitmap_ptr);
tsk->thread.io_bitmap_ptr = NULL;
tsk->thread.io_bitmap_max = 0;
}
}
int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
unsigned long arg, struct task_struct *p, unsigned long tls)
{
struct inactive_task_frame *frame;
struct fork_frame *fork_frame;
struct pt_regs *childregs;
int ret;
childregs = task_pt_regs(p);
fork_frame = container_of(childregs, struct fork_frame, regs);
frame = &fork_frame->frame;
frame->bp = 0;
frame->ret_addr = (unsigned long) ret_from_fork;
p->thread.sp = (unsigned long) fork_frame;
p->thread.io_bitmap_ptr = NULL;
memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
#ifdef CONFIG_X86_64
savesegment(gs, p->thread.gsindex);
p->thread.gsbase = p->thread.gsindex ? 0 : current->thread.gsbase;
savesegment(fs, p->thread.fsindex);
p->thread.fsbase = p->thread.fsindex ? 0 : current->thread.fsbase;
savesegment(es, p->thread.es);
savesegment(ds, p->thread.ds);
#else
p->thread.sp0 = (unsigned long) (childregs + 1);
/*
* Clear all status flags including IF and set fixed bit. 64bit
* does not have this initialization as the frame does not contain
* flags. The flags consistency (especially vs. AC) is there
* ensured via objtool, which lacks 32bit support.
*/
frame->flags = X86_EFLAGS_FIXED;
#endif
/* Kernel thread ? */
if (unlikely(p->flags & PF_KTHREAD)) {
memset(childregs, 0, sizeof(struct pt_regs));
kthread_frame_init(frame, sp, arg);
return 0;
}
frame->bx = 0;
*childregs = *current_pt_regs();
childregs->ax = 0;
if (sp)
childregs->sp = sp;
#ifdef CONFIG_X86_32
task_user_gs(p) = get_user_gs(current_pt_regs());
#endif
ret = copy_io_bitmap(p);
if (ret)
return ret;
/* Set a new TLS for the child thread? */
if (clone_flags & CLONE_SETTLS) {
ret = set_new_tls(p, tls);
if (ret)
free_io_bitmap(p);
}
return ret;
}
void flush_thread(void)
{
struct task_struct *tsk = current;

68
arch/x86/kernel/process_32.c
View File

@ -112,74 +112,6 @@ void release_thread(struct task_struct *dead_task)
release_vm86_irqs(dead_task);
}
int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
unsigned long arg, struct task_struct *p, unsigned long tls)
{
struct pt_regs *childregs = task_pt_regs(p);
struct fork_frame *fork_frame = container_of(childregs, struct fork_frame, regs);
struct inactive_task_frame *frame = &fork_frame->frame;
struct task_struct *tsk;
int err;
/*
* For a new task use the RESET flags value since there is no before.
* All the status flags are zero; DF and all the system flags must also
* be 0, specifically IF must be 0 because we context switch to the new
* task with interrupts disabled.
*/
frame->flags = X86_EFLAGS_FIXED;
frame->bp = 0;
frame->ret_addr = (unsigned long) ret_from_fork;
p->thread.sp = (unsigned long) fork_frame;
p->thread.sp0 = (unsigned long) (childregs+1);
memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
if (unlikely(p->flags & PF_KTHREAD)) {
/* kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
frame->bx = sp; /* function */
frame->di = arg;
p->thread.io_bitmap_ptr = NULL;
return 0;
}
frame->bx = 0;
*childregs = *current_pt_regs();
childregs->ax = 0;
if (sp)
childregs->sp = sp;
task_user_gs(p) = get_user_gs(current_pt_regs());
p->thread.io_bitmap_ptr = NULL;
tsk = current;
err = -ENOMEM;
if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
IO_BITMAP_BYTES, GFP_KERNEL);
if (!p->thread.io_bitmap_ptr) {
p->thread.io_bitmap_max = 0;
return -ENOMEM;
}
set_tsk_thread_flag(p, TIF_IO_BITMAP);
}
err = 0;
/*
* Set a new TLS for the child thread?
*/
if (clone_flags & CLONE_SETTLS)
err = do_set_thread_area(p, -1,
(struct user_desc __user *)tls, 0);
if (err && p->thread.io_bitmap_ptr) {
kfree(p->thread.io_bitmap_ptr);
p->thread.io_bitmap_max = 0;
}
return err;
}
void
start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
{

75
arch/x86/kernel/process_64.c
View File

@ -371,81 +371,6 @@ void x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase)
task->thread.gsbase = gsbase;
}
int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
unsigned long arg, struct task_struct *p, unsigned long tls)
{
int err;
struct pt_regs *childregs;
struct fork_frame *fork_frame;
struct inactive_task_frame *frame;
struct task_struct *me = current;
childregs = task_pt_regs(p);
fork_frame = container_of(childregs, struct fork_frame, regs);
frame = &fork_frame->frame;
frame->bp = 0;
frame->ret_addr = (unsigned long) ret_from_fork;
p->thread.sp = (unsigned long) fork_frame;
p->thread.io_bitmap_ptr = NULL;
savesegment(gs, p->thread.gsindex);
p->thread.gsbase = p->thread.gsindex ? 0 : me->thread.gsbase;
savesegment(fs, p->thread.fsindex);
p->thread.fsbase = p->thread.fsindex ? 0 : me->thread.fsbase;
savesegment(es, p->thread.es);
savesegment(ds, p->thread.ds);
memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
if (unlikely(p->flags & PF_KTHREAD)) {
/* kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
frame->bx = sp; /* function */
frame->r12 = arg;
return 0;
}
frame->bx = 0;
*childregs = *current_pt_regs();
childregs->ax = 0;
if (sp)
childregs->sp = sp;
err = -ENOMEM;
if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
p->thread.io_bitmap_ptr = kmemdup(me->thread.io_bitmap_ptr,
IO_BITMAP_BYTES, GFP_KERNEL);
if (!p->thread.io_bitmap_ptr) {
p->thread.io_bitmap_max = 0;
return -ENOMEM;
}
set_tsk_thread_flag(p, TIF_IO_BITMAP);
}
/*
* Set a new TLS for the child thread?
*/
if (clone_flags & CLONE_SETTLS) {
#ifdef CONFIG_IA32_EMULATION
if (in_ia32_syscall())
err = do_set_thread_area(p, -1,
(struct user_desc __user *)tls, 0);
else
#endif
err = do_arch_prctl_64(p, ARCH_SET_FS, tls);
if (err)
goto out;
}
err = 0;
out:
if (err && p->thread.io_bitmap_ptr) {
kfree(p->thread.io_bitmap_ptr);
p->thread.io_bitmap_max = 0;
}
return err;
}
static void
start_thread_common(struct pt_regs *regs, unsigned long new_ip,
unsigned long new_sp,