Merge tag 'clone3-tls-v5.5-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull thread fixes from Christian Brauner:
 "This contains a series of patches to fix CLONE_SETTLS when used with
  clone3().

  The clone3() syscall passes the tls argument through struct clone_args
  instead of a register. This means, all architectures that do not
  implement copy_thread_tls() but still support CLONE_SETTLS via
  copy_thread() expecting the tls to be located in a register argument
  based on clone() are currently unfortunately broken. Their tls value
  will be garbage.

  The patch series fixes this on all architectures that currently define
  __ARCH_WANT_SYS_CLONE3. It also adds a compile-time check to ensure
  that any architecture that enables clone3() in the future is forced to
  also implement copy_thread_tls().

  My ultimate goal is to get rid of the copy_thread()/copy_thread_tls()
  split and just have copy_thread_tls() at some point in the not too
  distant future (Maybe even renaming copy_thread_tls() back to simply
  copy_thread() once the old function is ripped from all arches). This
  is dependent now on all arches supporting clone3().

  While all relevant arches do that now there are still four missing:
  ia64, m68k, sh and sparc. They have the system call reserved, but not
  implemented. Once they all implement clone3() we can get rid of
  ARCH_WANT_SYS_CLONE3 and HAVE_COPY_THREAD_TLS.

  This series also includes a minor fix for the arm64 uapi headers which
  caused __NR_clone3 to be missing from the exported user headers.

  Unfortunately the series came in a little late especially given that
  it touches a range of architectures. Due to the holidays not all arch
  maintainers responded in time probably due to their backlog. Will and
  Arnd have thankfully acked the arm specific changes.

  Given that the changes are straightforward and rather minimal combined
  with the fact the that clone3() with CLONE_SETTLS is broken I decided
  to send them post rc3 nonetheless"

* tag 'clone3-tls-v5.5-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  um: Implement copy_thread_tls
  clone3: ensure copy_thread_tls is implemented
  xtensa: Implement copy_thread_tls
  riscv: Implement copy_thread_tls
  parisc: Implement copy_thread_tls
  arm: Implement copy_thread_tls
  arm64: Implement copy_thread_tls
  arm64: Move __ARCH_WANT_SYS_CLONE3 definition to uapi headers

Author: torvalds

arch/arm/Kconfig

@@ -72,6 +72,7 @@ config ARM
 	select HAVE_ARM_SMCCC if CPU_V7
 	select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32
 	select HAVE_CONTEXT_TRACKING
+	select HAVE_COPY_THREAD_TLS
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_CONTIGUOUS if MMU

arch/arm/kernel/process.c

@@ -226,8 +226,8 @@ void release_thread(struct task_struct *dead_task)
 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
 
 int
-copy_thread(unsigned long clone_flags, unsigned long stack_start,
-	    unsigned long stk_sz, struct task_struct *p)
+copy_thread_tls(unsigned long clone_flags, unsigned long stack_start,
+	    unsigned long stk_sz, struct task_struct *p, unsigned long tls)
 {
 	struct thread_info *thread = task_thread_info(p);
 	struct pt_regs *childregs = task_pt_regs(p);
@@ -261,7 +261,7 @@ copy_thread(unsigned long clone_flags, unsigned long stack_start,
 	clear_ptrace_hw_breakpoint(p);
 
 	if (clone_flags & CLONE_SETTLS)
-		thread->tp_value[0] = childregs->ARM_r3;
+		thread->tp_value[0] = tls;
 	thread->tp_value[1] = get_tpuser();
 
 	thread_notify(THREAD_NOTIFY_COPY, thread);

arch/arm64/Kconfig

@@ -138,6 +138,7 @@ config ARM64
 	select HAVE_CMPXCHG_DOUBLE
 	select HAVE_CMPXCHG_LOCAL
 	select HAVE_CONTEXT_TRACKING
+	select HAVE_COPY_THREAD_TLS
 	select HAVE_DEBUG_BUGVERBOSE
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_CONTIGUOUS

arch/arm64/include/asm/unistd.h

@@ -42,7 +42,6 @@
 #endif
 
 #define __ARCH_WANT_SYS_CLONE
-#define __ARCH_WANT_SYS_CLONE3
 
 #ifndef __COMPAT_SYSCALL_NR
 #include <uapi/asm/unistd.h>

arch/arm64/include/uapi/asm/unistd.h

@@ -19,5 +19,6 @@
 #define __ARCH_WANT_NEW_STAT
 #define __ARCH_WANT_SET_GET_RLIMIT
 #define __ARCH_WANT_TIME32_SYSCALLS
+#define __ARCH_WANT_SYS_CLONE3
 
 #include <asm-generic/unistd.h>

arch/arm64/kernel/process.c

@@ -360,8 +360,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 
 asmlinkage void ret_from_fork(void) asm("ret_from_fork");
 
-int copy_thread(unsigned long clone_flags, unsigned long stack_start,
-		unsigned long stk_sz, struct task_struct *p)
+int copy_thread_tls(unsigned long clone_flags, unsigned long stack_start,
+		unsigned long stk_sz, struct task_struct *p, unsigned long tls)
 {
 	struct pt_regs *childregs = task_pt_regs(p);
 
@@ -394,11 +394,11 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
 		}
 
 		/*
-		 * If a TLS pointer was passed to clone (4th argument), use it
-		 * for the new thread.
+		 * If a TLS pointer was passed to clone, use it for the new
+		 * thread.
 		 */
 		if (clone_flags & CLONE_SETTLS)
-			p->thread.uw.tp_value = childregs->regs[3];
+			p->thread.uw.tp_value = tls;
 	} else {
 		memset(childregs, 0, sizeof(struct pt_regs));
 		childregs->pstate = PSR_MODE_EL1h;

arch/parisc/Kconfig

@@ -62,6 +62,7 @@ config PARISC
 	select HAVE_FTRACE_MCOUNT_RECORD if HAVE_DYNAMIC_FTRACE
 	select HAVE_KPROBES_ON_FTRACE
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS
+	select HAVE_COPY_THREAD_TLS
 
 	help
 	  The PA-RISC microprocessor is designed by Hewlett-Packard and used

arch/parisc/kernel/process.c

@@ -208,8 +208,8 @@ arch_initcall(parisc_idle_init);
  * Copy architecture-specific thread state
  */
 int
-copy_thread(unsigned long clone_flags, unsigned long usp,
-	    unsigned long kthread_arg, struct task_struct *p)
+copy_thread_tls(unsigned long clone_flags, unsigned long usp,
+	    unsigned long kthread_arg, struct task_struct *p, unsigned long tls)
 {
 	struct pt_regs *cregs = &(p->thread.regs);
 	void *stack = task_stack_page(p);
@@ -254,9 +254,9 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
 		cregs->ksp = (unsigned long)stack + THREAD_SZ_ALGN + FRAME_SIZE;
 		cregs->kpc = (unsigned long) &child_return;
 
-		/* Setup thread TLS area from the 4th parameter in clone */
+		/* Setup thread TLS area */
 		if (clone_flags & CLONE_SETTLS)
-			cregs->cr27 = cregs->gr[23];
+			cregs->cr27 = tls;
 	}
 
 	return 0;

arch/riscv/Kconfig

@@ -65,6 +65,7 @@ config RISCV
 	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
 	select HAVE_ARCH_MMAP_RND_BITS if MMU
 	select ARCH_HAS_GCOV_PROFILE_ALL
+	select HAVE_COPY_THREAD_TLS
 
 config ARCH_MMAP_RND_BITS_MIN
 	default 18 if 64BIT

arch/riscv/kernel/process.c

@@ -99,8 +99,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 	return 0;
 }
 
-int copy_thread(unsigned long clone_flags, unsigned long usp,
-	unsigned long arg, struct task_struct *p)
+int copy_thread_tls(unsigned long clone_flags, unsigned long usp,
+	unsigned long arg, struct task_struct *p, unsigned long tls)
 {
 	struct pt_regs *childregs = task_pt_regs(p);
 
@@ -121,7 +121,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
 		if (usp) /* User fork */
 			childregs->sp = usp;
 		if (clone_flags & CLONE_SETTLS)
-			childregs->tp = childregs->a5;
+			childregs->tp = tls;
 		childregs->a0 = 0; /* Return value of fork() */
 		p->thread.ra = (unsigned long)ret_from_fork;
 	}