[PATCH 2/7] arm64: Implement copy_thread_tls

Amanieu d'Antras
2020-01-02T17:24:40Z

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-arm-kernel@lists.infradead.org
Cc: <stable@vger.kernel.org> # 5.3.x
---
arch/arm64/Kconfig | 1 +
arch/arm64/kernel/process.c | 10 +++++-----
2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index b1b4476ddb83..e688dfad0b72 100644
--- a/arch/arm64/Kconfig
+++ b/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
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 71f788cd2b18..d54586d5b031 100644
--- a/arch/arm64/kernel/process.c
+++ b/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;
--
2.24.1