[PATCH 5.4 64/78] um: Implement copy_thread_tls

Greg Kroah-Hartman
2020-01-14T10:19:06Z

From: Amanieu d'Antras <amanieu@gmail.com>

commit 457677c70c7672a4586b0b8abc396cc1ecdd376d upstream.

This is required for clone3 which passes the TLS value through a
struct rather than a register.

Signed-off-by: Amanieu d'Antras <amanieu@gmail.com>
Cc: linux-um@lists.infradead.org
Cc: <stable@vger.kernel.org> # 5.3.x
Link: https://lore.kernel.org/r/20200104123928.1048822-1-amanieu@gmail.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/um/Kconfig | 1 +
arch/um/include/asm/ptrace-generic.h | 2 +-
arch/um/kernel/process.c | 6 +++---
arch/x86/um/tls_32.c | 6 ++----
arch/x86/um/tls_64.c | 7 +++----
5 files changed, 10 insertions(+), 12 deletions(-)

--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -14,6 +14,7 @@ config UML
select HAVE_FUTEX_CMPXCHG if FUTEX
select HAVE_DEBUG_KMEMLEAK
select HAVE_DEBUG_BUGVERBOSE
+ select HAVE_COPY_THREAD_TLS
select GENERIC_IRQ_SHOW
select GENERIC_CPU_DEVICES
select GENERIC_CLOCKEVENTS
--- a/arch/um/include/asm/ptrace-generic.h
+++ b/arch/um/include/asm/ptrace-generic.h
@@ -36,7 +36,7 @@ extern long subarch_ptrace(struct task_s
extern unsigned long getreg(struct task_struct *child, int regno);
extern int putreg(struct task_struct *child, int regno, unsigned long value);

-extern int arch_copy_tls(struct task_struct *new);
+extern int arch_set_tls(struct task_struct *new, unsigned long tls);
extern void clear_flushed_tls(struct task_struct *task);
extern int syscall_trace_enter(struct pt_regs *regs);
extern void syscall_trace_leave(struct pt_regs *regs);
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -153,8 +153,8 @@ void fork_handler(void)
userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
}

-int copy_thread(unsigned long clone_flags, unsigned long sp,
- unsigned long arg, struct task_struct * p)
+int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
+ unsigned long arg, struct task_struct * p, unsigned long tls)
{
void (*handler)(void);
int kthread = current->flags & PF_KTHREAD;
@@ -188,7 +188,7 @@ int copy_thread(unsigned long clone_flag
* Set a new TLS for the child thread?
*/
if (clone_flags & CLONE_SETTLS)
- ret = arch_copy_tls(p);
+ ret = arch_set_tls(p, tls);
}

return ret;
--- a/arch/x86/um/tls_32.c
+++ b/arch/x86/um/tls_32.c
@@ -215,14 +215,12 @@ static int set_tls_entry(struct task_str
return 0;
}

-int arch_copy_tls(struct task_struct *new)
+int arch_set_tls(struct task_struct *new, unsigned long tls)
{
struct user_desc info;
int idx, ret = -EFAULT;

- if (copy_from_user(&info,
- (void __user *) UPT_SI(&new->thread.regs.regs),
- sizeof(info)))
+ if (copy_from_user(&info, (void __user *) tls, sizeof(info)))
goto out;

ret = -EINVAL;
--- a/arch/x86/um/tls_64.c
+++ b/arch/x86/um/tls_64.c
@@ -6,14 +6,13 @@ void clear_flushed_tls(struct task_struc
{
}

-int arch_copy_tls(struct task_struct *t)
+int arch_set_tls(struct task_struct *t, unsigned long tls)
{
/*
* If CLONE_SETTLS is set, we need to save the thread id
- * (which is argument 5, child_tid, of clone) so it can be set
- * during context switches.
+ * so it can be set during context switches.
*/
- t->thread.arch.fs = t->thread.regs.regs.gp[R8 / sizeof(long)];
+ t->thread.arch.fs = tls;

return 0;
}