powerpc: convert to copy_thread_tls

Commit 3033f14ab78c3 ("clone: support passing tls argument via C rather
than pt_regs magic") introduced the HAVE_COPY_THREAD_TLS option. Use it
to avoid a subtle assumption about the argument ordering of clone type
syscalls.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190827033010.28090-2-npiggin@gmail.com

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 3d65084..cfb2185 100644 (file)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -184,6 +184,7 @@ config PPC
        select HAVE_STACKPROTECTOR              if PPC64 && $(cc-option,-mstack-protector-guard=tls -mstack-protector-guard-reg=r13)
        select HAVE_STACKPROTECTOR              if PPC32 && $(cc-option,-mstack-protector-guard=tls -mstack-protector-guard-reg=r2)
        select HAVE_CONTEXT_TRACKING            if PPC64
+       select HAVE_COPY_THREAD_TLS
        select HAVE_DEBUG_KMEMLEAK
        select HAVE_DEBUG_STACKOVERFLOW
        select HAVE_DYNAMIC_FTRACE

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 8fc4de0..24621e7 100644 (file)
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1600,8 +1600,9 @@ static void setup_ksp_vsid(struct task_struct *p, unsigned long sp)
 /*
  * Copy architecture-specific thread state
  */
-int copy_thread(unsigned long clone_flags, unsigned long usp,
-               unsigned long kthread_arg, struct task_struct *p)
+int copy_thread_tls(unsigned long clone_flags, unsigned long usp,
+               unsigned long kthread_arg, struct task_struct *p,
+               unsigned long tls)
 {
        struct pt_regs *childregs, *kregs;
        extern void ret_from_fork(void);
@@ -1642,10 +1643,10 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
                if (clone_flags & CLONE_SETTLS) {
 #ifdef CONFIG_PPC64
                        if (!is_32bit_task())
-                               childregs->gpr[13] = childregs->gpr[6];
+                               childregs->gpr[13] = tls;
                        else
 #endif
-                               childregs->gpr[2] = childregs->gpr[6];
+                               childregs->gpr[2] = tls;
                }
 
                f = ret_from_fork;