Signed-off-by: Max Filippov <jcmvbkbc@xxxxxxxxx>
---
arch/xtensa/Kconfig | 1 +
arch/xtensa/include/asm/processor.h | 3 -
arch/xtensa/kernel/entry.S | 41 ++++++-------------
arch/xtensa/kernel/process.c | 72 +++++++++++++++++++++-------------
arch/xtensa/kernel/xtensa_ksyms.c | 1 -
5 files changed, 58 insertions(+), 60 deletions(-)
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index cdcb48a..9525b70 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -13,6 +13,7 @@ config XTENSA
select GENERIC_CPU_DEVICES
select MODULES_USE_ELF_RELA
select GENERIC_PCI_IOMAP
+ select GENERIC_KERNEL_THREAD
select ARCH_WANT_OPTIONAL_GPIOLIB
help
Xtensa processors are 32-bit RISC machines designed by Tensilica
diff --git a/arch/xtensa/include/asm/processor.h b/arch/xtensa/include/asm/processor.h
index 5c371d8..a8642da 100644
--- a/arch/xtensa/include/asm/processor.h
+++ b/arch/xtensa/include/asm/processor.h
@@ -168,9 +168,6 @@ struct mm_struct;
/* Free all resources held by a thread. */
#define release_thread(thread) do { } while(0)
-/* Create a kernel thread without removing it from tasklists */
-extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
-
/* Copy and release all segment info associated with a VM */
#define copy_segments(p, mm) do { } while(0)
#define release_segments(mm) do { } while(0)
diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index 18453067..d4ec138 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -1833,34 +1833,6 @@ ENTRY(system_call)
/*
- * Create a kernel thread
- *
- * int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
- * a2 a2 a3 a4
- */
-
-ENTRY(kernel_thread)
- entry a1, 16
-
- mov a5, a2 # preserve fn over syscall
- mov a7, a3 # preserve args over syscall
-
- movi a3, _CLONE_VM | _CLONE_UNTRACED
- movi a2, __NR_clone
- or a6, a4, a3 # arg0: flags
- mov a3, a1 # arg1: sp
- syscall
-
- beq a3, a1, 1f # branch if parent
- mov a6, a7 # args
- callx4 a5 # fn(args)
-
- movi a2, __NR_exit
- syscall # return value of fn(args) still in a6
-
-1: retw
-
-/*
* Do a system call from kernel instead of calling sys_execve, so we end up
* with proper pt_regs.
*
@@ -1958,3 +1930,16 @@ ENTRY(ret_from_fork)
j common_exception_return
+/*
+ * Kernel thread creation helper
+ * On entry, set up by copy_thread: a2 = thread_fn, a3 = thread_fn arg
+ * left from _switch_to: a6 = prev
+ */
+ENTRY(ret_from_kernel_thread)
+
+ call4 schedule_tail
+ mov a6, a3
+ callx4 a2
+ call4 do_exit
+
+ENDPROC(ret_from_kernel_thread)
diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c
index 1908f66..fd538bb 100644
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -45,6 +45,7 @@
#include <asm/regs.h>
extern void ret_from_fork(void);
+extern void ret_from_kernel_thread(void);
struct task_struct *current_set[NR_CPUS] = {&init_task, };
@@ -158,18 +159,30 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
/*
* Copy thread.
*
+ * There are two modes in which this function is called:
+ * 1) Userspace thread creation,
+ * regs != NULL, usp_thread_fn is userspace stack pointer.
+ * It is expected to copy parent regs (in case CLONE_VM is not set
+ * in the clone_flags) and set up passed usp in the childregs.
+ * 2) Kernel thread creation,
+ * regs == NULL, usp_thread_fn is the function to run in the new thread
+ * and thread_fn_arg is its parameter.
+ * childregs are not used for the kernel threads.
+ *
* The stack layout for the new thread looks like this:
*
- * +------------------------+ <- sp in childregs (= tos)
+ * +------------------------+
* | childregs |
* +------------------------+ <- thread.sp = sp in dummy-frame
* | dummy-frame | (saved in dummy-frame spill-area)
* +------------------------+
*
- * We create a dummy frame to return to ret_from_fork:
- * a0 points to ret_from_fork (simulating a call4)
+ * We create a dummy frame to return to either ret_from_fork or
+ * ret_from_kernel_thread:
+ * a0 points to ret_from_fork/ret_from_kernel_thread (simulating a call4)
* sp points to itself (thread.sp)
- * a2, a3 are unused.
+ * a2, a3 are unused for userspace threads,
+ * a2 points to thread_fn, a3 holds thread_fn arg for kernel threads.
*
* Note: This is a pristine frame, so we don't need any spill region on top of
* childregs.
@@ -185,41 +198,35 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
* involved. Much simpler to just not copy those live frames across.
*/
-int copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long unused,
+int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
+ unsigned long thread_fn_arg,
struct task_struct * p, struct pt_regs * regs)
{
- struct pt_regs *childregs;
- unsigned long tos;
- int user_mode = user_mode(regs);
+ struct pt_regs *childregs = task_pt_regs(p);
#if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
struct thread_info *ti;
#endif
- /* Set up new TSS. */
- tos = (unsigned long)task_stack_page(p) + THREAD_SIZE;
- if (user_mode)
- childregs = (struct pt_regs*)(tos - PT_USER_SIZE);
- else
- childregs = (struct pt_regs*)tos - 1;
-
- /* This does not copy all the regs. In a bout of brilliance or madness,
- ARs beyond a0-a15 exist past the end of the struct. */
- *childregs = *regs;
-
/* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
*((int*)childregs - 3) = (unsigned long)childregs;
*((int*)childregs - 4) = 0;
- childregs->areg[2] = 0;
p->set_child_tid = p->clear_child_tid = NULL;
- p->thread.ra = MAKE_RA_FOR_CALL((unsigned long)ret_from_fork, 0x1);
p->thread.sp = (unsigned long)childregs;
- if (user_mode(regs)) {
+ if (regs) {
+ p->thread.ra = MAKE_RA_FOR_CALL(
+ (unsigned long)ret_from_fork, 0x1);
+
+ /* This does not copy all the regs.
+ * In a bout of brilliance or madness,
+ * ARs beyond a0-a15 exist past the end of the struct.
+ */
+ *childregs = *regs;
+ childregs->areg[1] = usp_thread_fn;
+ childregs->areg[2] = 0;
- childregs->areg[1] = usp;
if (clone_flags & CLONE_VM) {
childregs->wmask = 1; /* can't share live windows */
} else {
@@ -230,11 +237,20 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
// FIXME: we need to set THREADPTR in thread_info...
if (clone_flags & CLONE_SETTLS)
childregs->areg[2] = childregs->areg[6];
-
} else {
- /* In kernel space, we start a new thread with a new stack. */
- childregs->wmask = 1;
- childregs->areg[1] = tos;
+ p->thread.ra = MAKE_RA_FOR_CALL(
+ (unsigned long)ret_from_kernel_thread, 1);
+
+ /* pass parameters to ret_from_kernel_thread:
+ * a2 = thread_fn, a3 = thread_fn arg
+ */
+ *((int *)childregs - 1) = thread_fn_arg;
+ *((int *)childregs - 2) = usp_thread_fn;
+
+ /* Childregs are only used when we're going to userspace
+ * in which case start_thread will set them up.
+ */
+ memset(childregs, 0, sizeof(*childregs));
}
#if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
diff --git a/arch/xtensa/kernel/xtensa_ksyms.c b/arch/xtensa/kernel/xtensa_ksyms.c
index a8b9f1f..afe058b 100644
--- a/arch/xtensa/kernel/xtensa_ksyms.c
+++ b/arch/xtensa/kernel/xtensa_ksyms.c
@@ -43,7 +43,6 @@ EXPORT_SYMBOL(__strncpy_user);
EXPORT_SYMBOL(clear_page);
EXPORT_SYMBOL(copy_page);
-EXPORT_SYMBOL(kernel_thread);
EXPORT_SYMBOL(empty_zero_page);
/*
--
1.7.7.6
--
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