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SubjectRe: [PATCH] um: Implement copy_thread_tls
On Sat, Jan 04, 2020 at 01:39:30PM +0100, Amanieu d'Antras wrote:
> 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

Thanks. I'm picking this up as part of the copy_thread_tls() series.
(Leaving the patch in tact so people can Ack right here if they want to.)
If I could get an Ack from one of the maintainers that would be great;
see
https://lore.kernel.org/lkml/20200102172413.654385-1-amanieu@gmail.com
for more context.

Acked-by: Christian Brauner <christian.brauner@ubuntu.com>

> ---
> 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(-)
>
> diff --git a/arch/um/Kconfig b/arch/um/Kconfig
> index 2a6d04fcb3e9..6f0edd0c0220 100644
> --- 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
> diff --git a/arch/um/include/asm/ptrace-generic.h b/arch/um/include/asm/ptrace-generic.h
> index 81c647ef9c6c..adf91ef553ae 100644
> --- 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_struct *child, long request,
> 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);
> diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
> index 263a8f069133..17045e7211bf 100644
> --- 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_flags, unsigned long sp,
> * 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;
> diff --git a/arch/x86/um/tls_32.c b/arch/x86/um/tls_32.c
> index 5bd949da7a4a..ac8eee093f9c 100644
> --- 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_struct* task, struct user_desc *info,
> 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;
> diff --git a/arch/x86/um/tls_64.c b/arch/x86/um/tls_64.c
> index 3a621e0d3925..ebd3855d9b13 100644
> --- a/arch/x86/um/tls_64.c
> +++ b/arch/x86/um/tls_64.c
> @@ -6,14 +6,13 @@ void clear_flushed_tls(struct task_struct *task)
> {
> }
>
> -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;
> }
> --
> 2.24.1
>

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