[PATCH 4/7] fork: Generalize PF_IO_WORKER handling

From: Eric W. Biederman
Date: Fri May 06 2022 - 10:15:58 EST

Add fn and fn_arg members into struct kernel_clone_args and test for
them in copy_thread (instead of testing for PF_KTHREAD | PF_IO_WORKER).
This allows any task that wants to be a user space task that only runs
in kernel mode to use this functionality.

The code on x86 is an exception and still retains a PF_KTHREAD test
because x86 unlikely everything else handles kthreads slightly
differently than user space tasks that start with a function.

The functions that created tasks that start with a function
have been updated to set ".fn" and ".fn_arg" instead of
".stack" and ".stack_size". These functions are fork_idle(),
create_io_thread(), kernel_thread(), and user_mode_thread().

Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
arch/alpha/kernel/process.c | 7 +++----
arch/arc/kernel/process.c | 7 +++----
arch/arm/kernel/process.c | 7 +++----
arch/arm64/kernel/process.c | 7 +++----
arch/csky/kernel/process.c | 7 +++----
arch/h8300/kernel/process.c | 7 +++----
arch/hexagon/kernel/process.c | 7 +++----
arch/ia64/kernel/process.c | 6 +++---
arch/m68k/kernel/process.c | 7 +++----
arch/microblaze/kernel/process.c | 7 +++----
arch/mips/kernel/process.c | 7 +++----
arch/nios2/kernel/process.c | 7 +++----
arch/openrisc/kernel/process.c | 7 +++----
arch/parisc/kernel/process.c | 11 +++++------
arch/powerpc/kernel/process.c | 9 ++++-----
arch/riscv/kernel/process.c | 7 +++----
arch/s390/kernel/process.c | 7 +++----
arch/sh/kernel/process_32.c | 7 +++----
arch/sparc/kernel/process_32.c | 7 +++----
arch/sparc/kernel/process_64.c | 7 +++----
arch/um/kernel/process.c | 10 ++++------
arch/x86/include/asm/fpu/sched.h | 2 +-
arch/x86/include/asm/switch_to.h | 8 ++++----
arch/x86/kernel/fpu/core.c | 4 ++--
arch/x86/kernel/process.c | 13 ++++++-------
arch/xtensa/kernel/process.c | 11 +++++------
include/linux/sched/task.h | 2 ++
kernel/fork.c | 16 ++++++++--------
28 files changed, 95 insertions(+), 116 deletions(-)

diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
index 732e39217c7f..6cbba7370b4e 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -237,7 +237,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long kthread_arg = args->stack_size;
unsigned long tls = args->tls;
extern void ret_from_fork(void);
extern void ret_from_kernel_thread(void);
@@ -251,13 +250,13 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
childti->pcb.ksp = (unsigned long) childstack;
childti->pcb.flags = 1; /* set FEN, clear everything else */

- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
/* kernel thread */
memset(childstack, 0,
sizeof(struct switch_stack) + sizeof(struct pt_regs));
childstack->r26 = (unsigned long) ret_from_kernel_thread;
- childstack->r9 = usp; /* function */
- childstack->r10 = kthread_arg;
+ childstack->r9 = (unsigned long) args->fn;
+ childstack->r10 = (unsigned long) args->fn_arg;
childregs->hae = alpha_mv.hae_cache;
childti->pcb.usp = 0;
return 0;
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c
index caf948ba647c..3369f0700702 100644
--- a/arch/arc/kernel/process.c
+++ b/arch/arc/kernel/process.c
@@ -166,7 +166,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long kthread_arg = args->stack_size;
unsigned long tls = args->tls;
struct pt_regs *c_regs; /* child's pt_regs */
unsigned long *childksp; /* to unwind out of __switch_to() */
@@ -193,11 +192,11 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
childksp[0] = 0; /* fp */
childksp[1] = (unsigned long)ret_from_fork; /* blink */

- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
memset(c_regs, 0, sizeof(struct pt_regs));

- c_callee->r13 = kthread_arg;
- c_callee->r14 = usp; /* function */
+ c_callee->r13 = (unsigned long)args->fn_arg;
+ c_callee->r14 = (unsigned long)args->fn;

return 0;
}
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 8e13b426dd26..3d9cace63884 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -242,7 +242,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long stack_start = args->stack;
- unsigned long stk_sz = args->stack_size;
unsigned long tls = args->tls;
struct thread_info *thread = task_thread_info(p);
struct pt_regs *childregs = task_pt_regs(p);
@@ -259,15 +258,15 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
thread->cpu_domain = get_domain();
#endif

- if (likely(!(p->flags & (PF_KTHREAD | PF_IO_WORKER)))) {
+ if (likely(!args->fn)) {
*childregs = *current_pt_regs();
childregs->ARM_r0 = 0;
if (stack_start)
childregs->ARM_sp = stack_start;
} else {
memset(childregs, 0, sizeof(struct pt_regs));
- thread->cpu_context.r4 = stk_sz;
- thread->cpu_context.r5 = stack_start;
+ thread->cpu_context.r4 = (unsigned long)args->fn_arg;
+ thread->cpu_context.r5 = (unsigned long)args->fn;
childregs->ARM_cpsr = SVC_MODE;
}
thread->cpu_context.pc = (unsigned long)ret_from_fork;
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index e002f6681c8d..d0ef05c661b0 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -320,7 +320,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long stack_start = args->stack;
- unsigned long stk_sz = args->stack_size;
unsigned long tls = args->tls;
struct pt_regs *childregs = task_pt_regs(p);

@@ -337,7 +336,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)

ptrauth_thread_init_kernel(p);

- if (likely(!(p->flags & (PF_KTHREAD | PF_IO_WORKER)))) {
+ if (likely(!args->fn)) {
*childregs = *current_pt_regs();
childregs->regs[0] = 0;

@@ -371,8 +370,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
memset(childregs, 0, sizeof(struct pt_regs));
childregs->pstate = PSR_MODE_EL1h | PSR_IL_BIT;

- p->thread.cpu_context.x19 = stack_start;
- p->thread.cpu_context.x20 = stk_sz;
+ p->thread.cpu_context.x19 = (unsigned long)args->fn;
+ p->thread.cpu_context.x20 = (unsigned long)args->fn_arg;
}
p->thread.cpu_context.pc = (unsigned long)ret_from_fork;
p->thread.cpu_context.sp = (unsigned long)childregs;
diff --git a/arch/csky/kernel/process.c b/arch/csky/kernel/process.c
index 7dba33d37e1a..9af49aea1c3b 100644
--- a/arch/csky/kernel/process.c
+++ b/arch/csky/kernel/process.c
@@ -34,7 +34,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long kthread_arg = args->stack_size;
unsigned long tls = args->tls;
struct switch_stack *childstack;
struct pt_regs *childregs = task_pt_regs(p);
@@ -49,11 +48,11 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
/* setup thread.sp for switch_to !!! */
p->thread.sp = (unsigned long)childstack;

- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
memset(childregs, 0, sizeof(struct pt_regs));
childstack->r15 = (unsigned long) ret_from_kernel_thread;
- childstack->r10 = kthread_arg;
- childstack->r9 = usp;
+ childstack->r10 = (unsigned long) args->fn_arg;
+ childstack->r9 = (unsigned long) args->fn;
childregs->sr = mfcr("psr");
} else {
*childregs = *(current_pt_regs());
diff --git a/arch/h8300/kernel/process.c b/arch/h8300/kernel/process.c
index 296ff831446e..5bfe0f8f54bf 100644
--- a/arch/h8300/kernel/process.c
+++ b/arch/h8300/kernel/process.c
@@ -108,16 +108,15 @@ void flush_thread(void)
int copy_thread(struct task_struct *p, const kernel_cloen_args *args)
{
unsigned long usp = args->stack;
- unsigned long topstk = args->stack_size;
struct pt_regs *childregs;

childregs = (struct pt_regs *) (THREAD_SIZE + task_stack_page(p)) - 1;

- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
memset(childregs, 0, sizeof(struct pt_regs));
childregs->retpc = (unsigned long) ret_from_kernel_thread;
- childregs->er4 = topstk; /* arg */
- childregs->er5 = usp; /* fn */
+ childregs->er4 = (unsigned long) args->fn_arg;
+ childregs->er5 = (unsigned long) args->fn;
} else {
*childregs = *current_pt_regs();
childregs->er0 = 0;
diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c
index f1c1f6f21941..f0552f98a7ba 100644
--- a/arch/hexagon/kernel/process.c
+++ b/arch/hexagon/kernel/process.c
@@ -54,7 +54,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long arg = args->stack_size;
unsigned long tls = args->tls;
struct thread_info *ti = task_thread_info(p);
struct hexagon_switch_stack *ss;
@@ -76,11 +75,11 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
sizeof(*ss));
ss->lr = (unsigned long)ret_from_fork;
p->thread.switch_sp = ss;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
memset(childregs, 0, sizeof(struct pt_regs));
/* r24 <- fn, r25 <- arg */
- ss->r24 = usp;
- ss->r25 = arg;
+ ss->r24 = (unsigned long)args->fn;
+ ss->r25 = (unsigned long)args->fn_arg;
pt_set_kmode(childregs);
return 0;
}
diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index 8f010ae818bc..167b1765bea1 100644
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -341,14 +341,14 @@ copy_thread(struct task_struct *p, const struct kernel_clone_args *args)

ia64_drop_fpu(p); /* don't pick up stale state from a CPU's fph */

- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
if (unlikely(args->idle)) {
/* fork_idle() called us */
return 0;
}
memset(child_stack, 0, sizeof(*child_ptregs) + sizeof(*child_stack));
- child_stack->r4 = user_stack_base; /* payload */
- child_stack->r5 = user_stack_size; /* argument */
+ child_stack->r4 = (unsigned long) args->fn;
+ child_stack->r5 = (unsigned long) args->fn_arg;
/*
* Preserve PSR bits, except for bits 32-34 and 37-45,
* which we can't read.
diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c
index 8ac575656fc4..221feb0269f1 100644
--- a/arch/m68k/kernel/process.c
+++ b/arch/m68k/kernel/process.c
@@ -142,7 +142,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long arg = args->stack_size;
unsigned long tls = args->tls;
struct fork_frame {
struct switch_stack sw;
@@ -160,12 +159,12 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
*/
p->thread.fc = USER_DATA;

- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
/* kernel thread */
memset(frame, 0, sizeof(struct fork_frame));
frame->regs.sr = PS_S;
- frame->sw.a3 = usp; /* function */
- frame->sw.d7 = arg;
+ frame->sw.a3 = (unsigned long)args->fn;
+ frame->sw.d7 = (unsigned long)args->fn_arg;
frame->sw.retpc = (unsigned long)ret_from_kernel_thread;
p->thread.usp = 0;
return 0;
diff --git a/arch/microblaze/kernel/process.c b/arch/microblaze/kernel/process.c
index b5f549125c6a..3c6241bcaea8 100644
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -56,19 +56,18 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long arg = args->stack_size;
unsigned long tls = args->tls;
struct pt_regs *childregs = task_pt_regs(p);
struct thread_info *ti = task_thread_info(p);

- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
/* if we're creating a new kernel thread then just zeroing all
* the registers. That's OK for a brand new thread.*/
memset(childregs, 0, sizeof(struct pt_regs));
memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
ti->cpu_context.r1 = (unsigned long)childregs;
- ti->cpu_context.r20 = (unsigned long)usp; /* fn */
- ti->cpu_context.r19 = (unsigned long)arg;
+ ti->cpu_context.r20 = (unsigned long)args->fn;
+ ti->cpu_context.r19 = (unsigned long)args->fn_arg;
childregs->pt_mode = 1;
local_save_flags(childregs->msr);
ti->cpu_context.msr = childregs->msr & ~MSR_IE;
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index a572d097b16b..35b912bce429 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -109,7 +109,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long kthread_arg = args->stack_size;
unsigned long tls = args->tls;
struct thread_info *ti = task_thread_info(p);
struct pt_regs *childregs, *regs = current_pt_regs();
@@ -122,12 +121,12 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
/* Put the stack after the struct pt_regs. */
childksp = (unsigned long) childregs;
p->thread.cp0_status = (read_c0_status() & ~(ST0_CU2|ST0_CU1)) | ST0_KERNEL_CUMASK;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
/* kernel thread */
unsigned long status = p->thread.cp0_status;
memset(childregs, 0, sizeof(struct pt_regs));
- p->thread.reg16 = usp; /* fn */
- p->thread.reg17 = kthread_arg;
+ p->thread.reg16 = (unsigned long)args->fn;
+ p->thread.reg17 = (unsigned long)args->fn_arg;
p->thread.reg29 = childksp;
p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
#if defined(CONFIG_CPU_R3000)
diff --git a/arch/nios2/kernel/process.c b/arch/nios2/kernel/process.c
index 98c4bfe972e0..29593b98567d 100644
--- a/arch/nios2/kernel/process.c
+++ b/arch/nios2/kernel/process.c
@@ -104,7 +104,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long arg = args->stack_size;
unsigned long tls = args->tls;
struct pt_regs *childregs = task_pt_regs(p);
struct pt_regs *regs;
@@ -112,12 +111,12 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
struct switch_stack *childstack =
((struct switch_stack *)childregs) - 1;

- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
memset(childstack, 0,
sizeof(struct switch_stack) + sizeof(struct pt_regs));

- childstack->r16 = usp; /* fn */
- childstack->r17 = arg;
+ childstack->r16 = (unsigned long) args->fn;
+ childstack->r17 = (unsigned long) args->fn_arg;
childstack->ra = (unsigned long) ret_from_kernel_thread;
childregs->estatus = STATUS_PIE;
childregs->sp = (unsigned long) childstack;
diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
index 486e46dd5883..d9697cc9bc4d 100644
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -156,7 +156,6 @@ copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long arg = args->stack_size;
unsigned long tls = args->tls;
struct pt_regs *userregs;
struct pt_regs *kregs;
@@ -175,10 +174,10 @@ copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
sp -= sizeof(struct pt_regs);
kregs = (struct pt_regs *)sp;

- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
memset(kregs, 0, sizeof(struct pt_regs));
- kregs->gpr[20] = usp; /* fn, kernel thread */
- kregs->gpr[22] = arg;
+ kregs->gpr[20] = (unsigned long)args->fn;
+ kregs->gpr[22] = (unsigned long)args->fn_arg;
} else {
*userregs = *current_pt_regs();

diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index 30a5874ca845..a6a2a558fc5b 100644
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -210,7 +210,6 @@ copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long kthread_arg = args->stack_size;
unsigned long tls = args->tls;
struct pt_regs *cregs = &(p->thread.regs);
void *stack = task_stack_page(p);
@@ -221,7 +220,7 @@ copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
extern void * const ret_from_kernel_thread;
extern void * const child_return;

- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
/* kernel thread */
memset(cregs, 0, sizeof(struct pt_regs));
if (args->idle) /* idle thread */
@@ -236,12 +235,12 @@ copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
* ret_from_kernel_thread.
*/
#ifdef CONFIG_64BIT
- cregs->gr[27] = ((unsigned long *)usp)[3];
- cregs->gr[26] = ((unsigned long *)usp)[2];
+ cregs->gr[27] = ((unsigned long *)args->fn)[3];
+ cregs->gr[26] = ((unsigned long *)args->fn)[2];
#else
- cregs->gr[26] = usp;
+ cregs->gr[26] = (unsigned long) args->fn;
#endif
- cregs->gr[25] = kthread_arg;
+ cregs->gr[25] = (unsigned long) args->fn_arg;
} else {
/* user thread */
/* usp must be word aligned. This also prevents users from
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3fd67c861d54..4f367bb68906 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1720,7 +1720,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long kthread_arg = args->stack_size;
unsigned long tls = args->tls;
struct pt_regs *childregs, *kregs;
extern void ret_from_fork(void);
@@ -1738,18 +1737,18 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
/* Copy registers */
sp -= sizeof(struct pt_regs);
childregs = (struct pt_regs *) sp;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
/* kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
childregs->gpr[1] = sp + sizeof(struct pt_regs);
/* function */
- if (usp)
- childregs->gpr[14] = ppc_function_entry((void *)usp);
+ if (args->fn)
+ childregs->gpr[14] = ppc_function_entry((void *)args->fn);
#ifdef CONFIG_PPC64
clear_tsk_thread_flag(p, TIF_32BIT);
childregs->softe = IRQS_ENABLED;
#endif
- childregs->gpr[15] = kthread_arg;
+ childregs->gpr[15] = (unsigned long)args->fn_arg;
p->thread.regs = NULL; /* no user register state */
ti->flags |= _TIF_RESTOREALL;
f = ret_from_kernel_thread;
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 334382731725..24efabdbc551 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -124,12 +124,11 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long arg = args->stack_size;
unsigned long tls = args->tls;
struct pt_regs *childregs = task_pt_regs(p);

/* p->thread holds context to be restored by __switch_to() */
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
/* Kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
childregs->gp = gp_in_global;
@@ -137,8 +136,8 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
childregs->status = SR_PP | SR_PIE;

p->thread.ra = (unsigned long)ret_from_kernel_thread;
- p->thread.s[0] = usp; /* fn */
- p->thread.s[1] = arg;
+ p->thread.s[0] = (unsigned long)args->fn;
+ p->thread.s[1] = (unsigned long)args->fn_arg;
} else {
*childregs = *(current_pt_regs());
if (usp) /* User fork */
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index bb5daec39516..89949b9f3cf8 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -98,7 +98,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long new_stackp = args->stack;
- unsigned long arg = args->stack_size;
unsigned long tls = args->tls;
struct fake_frame
{
@@ -133,15 +132,15 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
frame->sf.gprs[9] = (unsigned long)frame;

/* Store access registers to kernel stack of new process. */
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
/* kernel thread */
memset(&frame->childregs, 0, sizeof(struct pt_regs));
frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
frame->childregs.psw.addr =
(unsigned long)__ret_from_fork;
- frame->childregs.gprs[9] = new_stackp; /* function */
- frame->childregs.gprs[10] = arg;
+ frame->childregs.gprs[9] = (unsigned long)args->fn;
+ frame->childregs.gprs[10] = (unsigned long)args->fn_arg;
frame->childregs.orig_gpr2 = -1;
frame->childregs.last_break = 1;
return 0;
diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c
index 6023399b1892..a808843375e7 100644
--- a/arch/sh/kernel/process_32.c
+++ b/arch/sh/kernel/process_32.c
@@ -96,7 +96,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
- unsigned long arg = args->stack_size;
unsigned long tls = args->tls;
struct thread_info *ti = task_thread_info(p);
struct pt_regs *childregs;
@@ -117,11 +116,11 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)

childregs = task_pt_regs(p);
p->thread.sp = (unsigned long) childregs;
- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
memset(childregs, 0, sizeof(struct pt_regs));
p->thread.pc = (unsigned long) ret_from_kernel_thread;
- childregs->regs[4] = arg;
- childregs->regs[5] = usp;
+ childregs->regs[4] = (unsigned long) args->fn_arg;
+ childregs->regs[5] = (unsigned long) args->fn;
childregs->sr = SR_MD;
#if defined(CONFIG_SH_FPU)
childregs->sr |= SR_FD;
diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
index 80e6775e18c0..33b0215a4182 100644
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -263,7 +263,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long sp = args->stack;
- unsigned long arg = args->stack_size;
unsigned long tls = args->tls;
struct thread_info *ti = task_thread_info(p);
struct pt_regs *childregs, *regs = current_pt_regs();
@@ -299,13 +298,13 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
ti->ksp = (unsigned long) new_stack;
p->thread.kregs = childregs;

- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
extern int nwindows;
unsigned long psr;
memset(new_stack, 0, STACKFRAME_SZ + TRACEREG_SZ);
ti->kpc = (((unsigned long) ret_from_kernel_thread) - 0x8);
- childregs->u_regs[UREG_G1] = sp; /* function */
- childregs->u_regs[UREG_G2] = arg;
+ childregs->u_regs[UREG_G1] = (unsigned long) args->fn;
+ childregs->u_regs[UREG_G2] = (unsigned long) args->fn_arg;
psr = childregs->psr = get_psr();
ti->kpsr = psr | PSR_PIL;
ti->kwim = 1 << (((psr & PSR_CWP) + 1) % nwindows);
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 38c46ca826d9..6335b698a4b4 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -568,7 +568,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long sp = args->stack;
- unsigned long arg = args->stack_size;
unsigned long tls = args->tls;
struct thread_info *t = task_thread_info(p);
struct pt_regs *regs = current_pt_regs();
@@ -587,12 +586,12 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
sizeof(struct sparc_stackf));
t->fpsaved[0] = 0;

- if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (unlikely(args->fn)) {
memset(child_trap_frame, 0, child_stack_sz);
__thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] =
(current_pt_regs()->tstate + 1) & TSTATE_CWP;
- t->kregs->u_regs[UREG_G1] = sp; /* function */
- t->kregs->u_regs[UREG_G2] = arg;
+ t->kregs->u_regs[UREG_G1] = (unsigned long) args->fn;
+ t->kregs->u_regs[UREG_G2] = (unsigned long) args->fn_arg;
return 0;
}

diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index fd2d2361484d..181cc9aafb25 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -158,15 +158,13 @@ int copy_thread(struct task_struct * p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long sp = args->stack;
- unsigned long arg = args->stack_size;
unsigned long tls = args->tls;
void (*handler)(void);
- int kthread = current->flags & (PF_KTHREAD | PF_IO_WORKER);
int ret = 0;

p->thread = (struct thread_struct) INIT_THREAD;

- if (!kthread) {
+ if (!args->fn) {
memcpy(&p->thread.regs.regs, current_pt_regs(),
sizeof(p->thread.regs.regs));
PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
@@ -178,14 +176,14 @@ int copy_thread(struct task_struct * p, const struct kernel_clone_args *args)
arch_copy_thread(&current->thread.arch, &p->thread.arch);
} else {
get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
- p->thread.request.u.thread.proc = (int (*)(void *))sp;
- p->thread.request.u.thread.arg = (void *)arg;
+ p->thread.request.u.thread.proc = args->fn;
+ p->thread.request.u.thread.arg = args->fn_arg;
handler = new_thread_handler;
}

new_thread(task_stack_page(p), &p->thread.switch_buf, handler);

- if (!kthread) {
+ if (!args->fn) {
clear_flushed_tls(p);

/*
diff --git a/arch/x86/include/asm/fpu/sched.h b/arch/x86/include/asm/fpu/sched.h
index 99a8820e8cc4..b2486b2cbc6e 100644
--- a/arch/x86/include/asm/fpu/sched.h
+++ b/arch/x86/include/asm/fpu/sched.h
@@ -11,7 +11,7 @@

extern void save_fpregs_to_fpstate(struct fpu *fpu);
extern void fpu__drop(struct fpu *fpu);
-extern int fpu_clone(struct task_struct *dst, unsigned long clone_flags);
+extern int fpu_clone(struct task_struct *dst, unsigned long clone_flags, bool minimal);
extern void fpu_flush_thread(void);

/*
diff --git a/arch/x86/include/asm/switch_to.h b/arch/x86/include/asm/switch_to.h
index b5f0d2ff47e4..c08eb0fdd11f 100644
--- a/arch/x86/include/asm/switch_to.h
+++ b/arch/x86/include/asm/switch_to.h
@@ -78,13 +78,13 @@ static inline void update_task_stack(struct task_struct *task)
}

static inline void kthread_frame_init(struct inactive_task_frame *frame,
- unsigned long fun, unsigned long arg)
+ int (*fun)(void *), void *arg)
{
- frame->bx = fun;
+ frame->bx = (unsigned long)fun;
#ifdef CONFIG_X86_32
- frame->di = arg;
+ frame->di = (unsigned long)arg;
#else
- frame->r12 = arg;
+ frame->r12 = (unsigned long)arg;
#endif
}

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index c049561f373a..fbade5a3975b 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -556,7 +556,7 @@ static inline void fpu_inherit_perms(struct fpu *dst_fpu)
}

/* Clone current's FPU state on fork */
-int fpu_clone(struct task_struct *dst, unsigned long clone_flags)
+int fpu_clone(struct task_struct *dst, unsigned long clone_flags, bool minimal)
{
struct fpu *src_fpu = &current->thread.fpu;
struct fpu *dst_fpu = &dst->thread.fpu;
@@ -579,7 +579,7 @@ int fpu_clone(struct task_struct *dst, unsigned long clone_flags)
* No FPU state inheritance for kernel threads and IO
* worker threads.
*/
- if (dst->flags & (PF_KTHREAD | PF_IO_WORKER)) {
+ if (minimal) {
/* Clear out the minimal state */
memcpy(&dst_fpu->fpstate->regs, &init_fpstate.regs,
init_fpstate_copy_size());
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 0fce52b10dc4..d20eaad52a85 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -134,7 +134,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long sp = args->stack;
- unsigned long arg = args->stack_size;
unsigned long tls = args->tls;
struct inactive_task_frame *frame;
struct fork_frame *fork_frame;
@@ -172,13 +171,13 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
frame->flags = X86_EFLAGS_FIXED;
#endif

- fpu_clone(p, clone_flags);
+ fpu_clone(p, clone_flags, args->fn);

/* Kernel thread ? */
if (unlikely(p->flags & PF_KTHREAD)) {
p->thread.pkru = pkru_get_init_value();
memset(childregs, 0, sizeof(struct pt_regs));
- kthread_frame_init(frame, sp, arg);
+ kthread_frame_init(frame, args->fn, args->fn_arg);
return 0;
}

@@ -198,10 +197,10 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
task_user_gs(p) = get_user_gs(current_pt_regs());
#endif

- if (unlikely(p->flags & PF_IO_WORKER)) {
+ if (unlikely(args->fn)) {
/*
- * An IO thread is a user space thread, but it doesn't
- * return to ret_after_fork().
+ * A user space thread, but it doesn't return to
+ * ret_after_fork().
*
* In order to indicate that to tools like gdb,
* we reset the stack and instruction pointers.
@@ -211,7 +210,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
*/
childregs->sp = 0;
childregs->ip = 0;
- kthread_frame_init(frame, sp, arg);
+ kthread_frame_init(frame, args->fn, args->fn_arg);
return 0;
}

diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c
index 15ce25073142..c3751cc88e5d 100644
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -205,7 +205,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp_thread_fn = args->stack;
- unsigned long thread_fn_arg = args->stack_size;
unsigned long tls = args->tls;
struct pt_regs *childregs = task_pt_regs(p);

@@ -226,7 +225,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
#error Unsupported Xtensa ABI
#endif

- if (!(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
+ if (!args->fn) {
struct pt_regs *regs = current_pt_regs();
unsigned long usp = usp_thread_fn ?
usp_thread_fn : regs->areg[1];
@@ -278,15 +277,15 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
* Window underflow will load registers from the
* spill slots on the stack on return from _switch_to.
*/
- SPILL_SLOT(childregs, 2) = usp_thread_fn;
- SPILL_SLOT(childregs, 3) = thread_fn_arg;
+ SPILL_SLOT(childregs, 2) = (unsigned long)args->fn;
+ SPILL_SLOT(childregs, 3) = (unsigned long)args->fn_arg;
#elif defined(__XTENSA_CALL0_ABI__)
/*
* a12 = thread_fn, a13 = thread_fn arg.
* _switch_to epilogue will load registers from the stack.
*/
- ((unsigned long *)p->thread.sp)[0] = usp_thread_fn;
- ((unsigned long *)p->thread.sp)[1] = thread_fn_arg;
+ ((unsigned long *)p->thread.sp)[0] = (unsigned long)args->fn;
+ ((unsigned long *)p->thread.sp)[1] = (unsigned long)args->fn_arg;
#else
#error Unsupported Xtensa ABI
#endif
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 3d6b99ce5408..505aaf9fe477 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -34,6 +34,8 @@ struct kernel_clone_args {
int io_thread;
int kthread;
int idle;
+ int (*fn)(void *);
+ void *fn_arg;
struct cgroup *cgrp;
struct css_set *cset;
};
diff --git a/kernel/fork.c b/kernel/fork.c
index 93d77ee921ff..8e17c3fbce42 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2555,8 +2555,8 @@ struct task_struct * __init fork_idle(int cpu)
struct task_struct *task;
struct kernel_clone_args args = {
.flags = CLONE_VM,
- .stack = (unsigned long)&idle_dummy,
- .stack_size = (unsigned long)NULL,
+ .fn = &idle_dummy,
+ .fn_arg = NULL,
.kthread = 1,
.idle = 1,
};
@@ -2589,8 +2589,8 @@ struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
.flags = ((lower_32_bits(flags) | CLONE_VM |
CLONE_UNTRACED) & ~CSIGNAL),
.exit_signal = (lower_32_bits(flags) & CSIGNAL),
- .stack = (unsigned long)fn,
- .stack_size = (unsigned long)arg,
+ .fn = fn,
+ .fn_arg = arg,
.io_thread = 1,
};

@@ -2694,8 +2694,8 @@ pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
.flags = ((lower_32_bits(flags) | CLONE_VM |
CLONE_UNTRACED) & ~CSIGNAL),
.exit_signal = (lower_32_bits(flags) & CSIGNAL),
- .stack = (unsigned long)fn,
- .stack_size = (unsigned long)arg,
+ .fn = fn,
+ .fn_arg = arg,
.kthread = 1,
};

@@ -2711,8 +2711,8 @@ pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags)
.flags = ((lower_32_bits(flags) | CLONE_VM |
CLONE_UNTRACED) & ~CSIGNAL),
.exit_signal = (lower_32_bits(flags) & CSIGNAL),
- .stack = (unsigned long)fn,
- .stack_size = (unsigned long)arg,
+ .fn = fn,
+ .fn_arg = arg,
};

return kernel_clone(&args);
--
2.35.3