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Commit facd04a9 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
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powerpc: convert to copy_thread_tls 



Commit 3033f14a ("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: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190827033010.28090-2-npiggin@gmail.com
parent c7bf1252

arch/powerpc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/kernel/process.c

+5 −4
Original line number Diff line number Diff line
@@ -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;