linux-kernel - [PATCH] um: Implement copy_thread

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Message-Id: <20200104123928.1048822-1-amanieu@gmail.com>
Date:   Sat,  4 Jan 2020 13:39:30 +0100
From:   Amanieu d'Antras <amanieu@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Christian Brauner <christian@...uner.io>,
        Amanieu d'Antras <amanieu@...il.com>,
        linux-um@...ts.infradead.org, stable@...r.kernel.org
Subject: [PATCH] um: Implement copy_thread_tls

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

Signed-off-by: Amanieu d'Antras <amanieu@...il.com>
Cc: linux-um@...ts.infradead.org
Cc: <stable@...r.kernel.org> # 5.3.x
---
 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