[PATCH v2 1/3] Make _do_fork support return to caller's code

From: Zhao Lei
Date: Fri Mar 18 2016 - 08:51:01 EST

Currently, _do_fork() have following action:
1: Called by user task
New task return to user space code directly, bypass remain
kernel space code.
2: Called by kthread
New task run into callback function in kernel space specified
by _do_fork() caller.

In somecase, we need to fork a new task in user process's context,
it is used for next patch to fix core dump's security problem in
container.

This patch add a argument named return_to_kernel to _do_fork(),
to make new task always return to kernel_space with this argument.

Signed-off-by: Zhao Lei <zhaolei@xxxxxxxxxxxxxx>
---
arch/alpha/kernel/process.c | 4 ++--
arch/arc/kernel/process.c | 4 ++--
arch/arm/kernel/process.c | 4 ++--
arch/arm64/kernel/process.c | 5 +++--
arch/avr32/kernel/process.c | 5 +++--
arch/blackfin/kernel/process.c | 5 +++--
arch/c6x/kernel/process.c | 5 +++--
arch/cris/arch-v10/kernel/process.c | 4 ++--
arch/cris/arch-v32/kernel/process.c | 4 ++--
arch/frv/kernel/process.c | 4 ++--
arch/h8300/kernel/process.c | 4 ++--
arch/hexagon/kernel/process.c | 4 ++--
arch/ia64/kernel/process.c | 4 ++--
arch/m32r/kernel/process.c | 4 ++--
arch/m68k/kernel/process.c | 4 ++--
arch/metag/kernel/process.c | 5 +++--
arch/microblaze/kernel/process.c | 4 ++--
arch/mips/kernel/process.c | 4 ++--
arch/mn10300/kernel/process.c | 4 ++--
arch/nios2/kernel/process.c | 5 +++--
arch/openrisc/kernel/process.c | 4 ++--
arch/parisc/kernel/process.c | 5 +++--
arch/powerpc/kernel/process.c | 5 +++--
arch/s390/kernel/process.c | 4 ++--
arch/score/kernel/process.c | 4 ++--
arch/sh/kernel/process_32.c | 4 ++--
arch/sh/kernel/process_64.c | 4 ++--
arch/sparc/kernel/process_32.c | 4 ++--
arch/sparc/kernel/process_64.c | 4 ++--
arch/tile/kernel/process.c | 4 ++--
arch/um/kernel/process.c | 22 ++++++++++++----------
arch/unicore32/kernel/process.c | 4 ++--
arch/x86/kernel/process_32.c | 5 +++--
arch/x86/kernel/process_64.c | 5 +++--
arch/xtensa/kernel/process.c | 5 +++--
include/linux/sched.h | 11 ++++++-----
kernel/fork.c | 24 ++++++++++++++----------
37 files changed, 111 insertions(+), 93 deletions(-)

diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
index 84d1326..8c8b497 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -241,7 +241,7 @@ release_thread(struct task_struct *dead_task)
int
copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long kthread_arg,
- struct task_struct *p)
+ struct task_struct *p, int return_to_kernel)
{
extern void ret_from_fork(void);
extern void ret_from_kernel_thread(void);
@@ -255,7 +255,7 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
childti->pcb.ksp = (unsigned long) childstack;
childti->pcb.flags = 1; /* set FEN, clear everything else */

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
/* kernel thread */
memset(childstack, 0,
sizeof(struct switch_stack) + sizeof(struct pt_regs));
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c
index a3f750e..252befc 100644
--- a/arch/arc/kernel/process.c
+++ b/arch/arc/kernel/process.c
@@ -88,7 +88,7 @@ asmlinkage void ret_from_fork(void);
*/
int copy_thread(unsigned long clone_flags,
unsigned long usp, unsigned long kthread_arg,
- struct task_struct *p)
+ struct task_struct *p, int return_to_kernel)
{
struct pt_regs *c_regs; /* child's pt_regs */
unsigned long *childksp; /* to unwind out of __switch_to() */
@@ -115,7 +115,7 @@ int copy_thread(unsigned long clone_flags,
childksp[0] = 0; /* fp */
childksp[1] = (unsigned long)ret_from_fork; /* blink */

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

c_callee->r13 = kthread_arg;
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 4adfb46..f1acaf0 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -222,7 +222,7 @@ 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)
+ unsigned long stk_sz, struct task_struct *p, int return_to_kernel)
{
struct thread_info *thread = task_thread_info(p);
struct pt_regs *childregs = task_pt_regs(p);
@@ -239,7 +239,7 @@ copy_thread(unsigned long clone_flags, unsigned long stack_start,
thread->cpu_domain = get_domain();
#endif

- if (likely(!(p->flags & PF_KTHREAD))) {
+ if (likely(!(p->flags & PF_KTHREAD)) && !return_to_kernel) {
*childregs = *current_pt_regs();
childregs->ARM_r0 = 0;
if (stack_start)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 88d742b..62a38eb 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -245,13 +245,14 @@ 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)
+ unsigned long stk_sz, struct task_struct *p,
+ int return_to_kernel)
{
struct pt_regs *childregs = task_pt_regs(p);

memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));

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

diff --git a/arch/avr32/kernel/process.c b/arch/avr32/kernel/process.c
index 42a53e74..4ac993f 100644
--- a/arch/avr32/kernel/process.c
+++ b/arch/avr32/kernel/process.c
@@ -281,11 +281,12 @@ asmlinkage void syscall_return(void);

int copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long arg,
- struct task_struct *p)
+ struct task_struct *p,
+ int return_to_kernel)
{
struct pt_regs *childregs = task_pt_regs(p);

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
memset(childregs, 0, sizeof(struct pt_regs));
p->thread.cpu_context.r0 = arg;
p->thread.cpu_context.r1 = usp; /* fn */
diff --git a/arch/blackfin/kernel/process.c b/arch/blackfin/kernel/process.c
index 4aa5545..23d8655 100644
--- a/arch/blackfin/kernel/process.c
+++ b/arch/blackfin/kernel/process.c
@@ -112,14 +112,15 @@ asmlinkage int bfin_clone(unsigned long clone_flags, unsigned long newsp)
int
copy_thread(unsigned long clone_flags,
unsigned long usp, unsigned long topstk,
- struct task_struct *p)
+ struct task_struct *p,
+ int return_to_kernel)
{
struct pt_regs *childregs;
unsigned long *v;

childregs = (struct pt_regs *) (task_stack_page(p) + THREAD_SIZE) - 1;
v = ((unsigned long *)childregs) - 2;
- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
memset(childregs, 0, sizeof(struct pt_regs));
v[0] = usp;
v[1] = topstk;
diff --git a/arch/c6x/kernel/process.c b/arch/c6x/kernel/process.c
index 3ae9f5a..31fa2ad 100644
--- a/arch/c6x/kernel/process.c
+++ b/arch/c6x/kernel/process.c
@@ -112,13 +112,14 @@ void start_thread(struct pt_regs *regs, unsigned int pc, unsigned long usp)
*/
int copy_thread(unsigned long clone_flags, unsigned long usp,
unsigned long ustk_size,
- struct task_struct *p)
+ struct task_struct *p,
+ int return_to_kernel)
{
struct pt_regs *childregs;

childregs = task_pt_regs(p);

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
/* case of __kernel_thread: we return to supervisor space */
memset(childregs, 0, sizeof(struct pt_regs));
childregs->sp = (unsigned long)(childregs + 1);
diff --git a/arch/cris/arch-v10/kernel/process.c b/arch/cris/arch-v10/kernel/process.c
index 02b7834..d03a6bf 100644
--- a/arch/cris/arch-v10/kernel/process.c
+++ b/arch/cris/arch-v10/kernel/process.c
@@ -95,7 +95,7 @@ asmlinkage void ret_from_fork(void);
asmlinkage void ret_from_kernel_thread(void);

int copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct pt_regs *childregs = task_pt_regs(p);
struct switch_stack *swstack = ((struct switch_stack *)childregs) - 1;
@@ -104,7 +104,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
* remember that the task_struct doubles as the kernel stack for the task
*/

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
memset(swstack, 0,
sizeof(struct switch_stack) + sizeof(struct pt_regs));
swstack->r1 = usp;
diff --git a/arch/cris/arch-v32/kernel/process.c b/arch/cris/arch-v32/kernel/process.c
index c7ce784..aa6b71f 100644
--- a/arch/cris/arch-v32/kernel/process.c
+++ b/arch/cris/arch-v32/kernel/process.c
@@ -103,7 +103,7 @@ extern asmlinkage void ret_from_kernel_thread(void);

int
copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct pt_regs *childregs = task_pt_regs(p);
struct switch_stack *swstack = ((struct switch_stack *) childregs) - 1;
@@ -113,7 +113,7 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
* fix it up. Note: the task_struct doubles as the kernel stack for the
* task.
*/
- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
memset(swstack, 0,
sizeof(struct switch_stack) + sizeof(struct pt_regs));
swstack->r1 = usp;
diff --git a/arch/frv/kernel/process.c b/arch/frv/kernel/process.c
index 5d40aeb77..5f7d8a8 100644
--- a/arch/frv/kernel/process.c
+++ b/arch/frv/kernel/process.c
@@ -127,7 +127,7 @@ inline unsigned long user_stack(const struct pt_regs *regs)
*/
int copy_thread(unsigned long clone_flags,
unsigned long usp, unsigned long arg,
- struct task_struct *p)
+ struct task_struct *p, int return_to_kernel)
{
struct pt_regs *childregs;

@@ -144,7 +144,7 @@ int copy_thread(unsigned long clone_flags,
p->thread.lr = 0;
p->thread.frame0 = childregs;

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
childregs->gr9 = usp; /* function */
childregs->gr8 = arg;
p->thread.pc = (unsigned long) ret_from_kernel_thread;
diff --git a/arch/h8300/kernel/process.c b/arch/h8300/kernel/process.c
index dee4125..c6613bd 100644
--- a/arch/h8300/kernel/process.c
+++ b/arch/h8300/kernel/process.c
@@ -104,13 +104,13 @@ void flush_thread(void)

int copy_thread(unsigned long clone_flags,
unsigned long usp, unsigned long topstk,
- struct task_struct *p)
+ struct task_struct *p, int return_to_kernel)
{
struct pt_regs *childregs;

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

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
memset(childregs, 0, sizeof(struct pt_regs));
childregs->retpc = (unsigned long) ret_from_kernel_thread;
childregs->er4 = topstk; /* arg */
diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c
index a9ebd47..920604b 100644
--- a/arch/hexagon/kernel/process.c
+++ b/arch/hexagon/kernel/process.c
@@ -69,7 +69,7 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
* Copy architecture-specific thread state
*/
int copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct thread_info *ti = task_thread_info(p);
struct hexagon_switch_stack *ss;
@@ -91,7 +91,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
sizeof(*ss));
ss->lr = (unsigned long)ret_from_fork;
p->thread.switch_sp = ss;
- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
memset(childregs, 0, sizeof(struct pt_regs));
/* r24 <- fn, r25 <- arg */
ss->r24 = usp;
diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index b515149..a5ff431 100644
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -333,7 +333,7 @@ ia64_load_extra (struct task_struct *task)
int
copy_thread(unsigned long clone_flags,
unsigned long user_stack_base, unsigned long user_stack_size,
- struct task_struct *p)
+ struct task_struct *p, int return_to_kernel)
{
extern char ia64_ret_from_clone;
struct switch_stack *child_stack, *stack;
@@ -375,7 +375,7 @@ copy_thread(unsigned long clone_flags,

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

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
if (unlikely(!user_stack_base)) {
/* fork_idle() called us */
return 0;
diff --git a/arch/m32r/kernel/process.c b/arch/m32r/kernel/process.c
index e69221d..aec7068 100644
--- a/arch/m32r/kernel/process.c
+++ b/arch/m32r/kernel/process.c
@@ -129,13 +129,13 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
}

int copy_thread(unsigned long clone_flags, unsigned long spu,
- unsigned long arg, struct task_struct *tsk)
+ unsigned long arg, struct task_struct *tsk, int return_to_kernel)
{
struct pt_regs *childregs = task_pt_regs(tsk);
extern void ret_from_fork(void);
extern void ret_from_kernel_thread(void);

- if (unlikely(tsk->flags & PF_KTHREAD)) {
+ if (unlikely(tsk->flags & PF_KTHREAD) || return_to_kernel) {
memset(childregs, 0, sizeof(struct pt_regs));
childregs->psw = M32R_PSW_BIE;
childregs->r1 = spu; /* fn */
diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c
index c55ff71..2c3e3d3 100644
--- a/arch/m68k/kernel/process.c
+++ b/arch/m68k/kernel/process.c
@@ -130,7 +130,7 @@ asmlinkage int m68k_clone(struct pt_regs *regs)
}

int copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct fork_frame {
struct switch_stack sw;
@@ -148,7 +148,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
*/
p->thread.fs = get_fs().seg;

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
/* kernel thread */
memset(frame, 0, sizeof(struct fork_frame));
frame->regs.sr = PS_S;
diff --git a/arch/metag/kernel/process.c b/arch/metag/kernel/process.c
index 7f54618..2e78cd4 100644
--- a/arch/metag/kernel/process.c
+++ b/arch/metag/kernel/process.c
@@ -178,7 +178,8 @@ void show_regs(struct pt_regs *regs)
* Copy architecture-specific thread state
*/
int copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long kthread_arg, struct task_struct *tsk)
+ unsigned long kthread_arg, struct task_struct *tsk,
+ int return_to_kernel)
{
struct pt_regs *childregs = task_pt_regs(tsk);
void *kernel_context = ((void *) childregs +
@@ -195,7 +196,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
ret_from_fork,
0, 0);

- if (unlikely(tsk->flags & PF_KTHREAD)) {
+ if (unlikely(tsk->flags & PF_KTHREAD) || return_to_kernel) {
/*
* Make sure we don't leak any kernel data to child's regs
* if kernel thread becomes a userspace thread in the future
diff --git a/arch/microblaze/kernel/process.c b/arch/microblaze/kernel/process.c
index b2dd3719..60e6e80 100644
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -52,12 +52,12 @@ void flush_thread(void)
}

int copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct pt_regs *childregs = task_pt_regs(p);
struct thread_info *ti = task_thread_info(p);

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
/* 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));
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index eddd5fd..be41191 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -109,7 +109,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
* Copy architecture-specific thread state
*/
int copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long kthread_arg, struct task_struct *p)
+ unsigned long kthread_arg, struct task_struct *p, int return_to_kernel)
{
struct thread_info *ti = task_thread_info(p);
struct pt_regs *childregs, *regs = current_pt_regs();
@@ -123,7 +123,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
/* Put the stack after the struct pt_regs. */
childksp = (unsigned long) childregs;
p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
/* kernel thread */
unsigned long status = p->thread.cp0_status;
memset(childregs, 0, sizeof(struct pt_regs));
diff --git a/arch/mn10300/kernel/process.c b/arch/mn10300/kernel/process.c
index 3707da5..cbf0fbe 100644
--- a/arch/mn10300/kernel/process.c
+++ b/arch/mn10300/kernel/process.c
@@ -142,7 +142,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
*/
int copy_thread(unsigned long clone_flags,
unsigned long c_usp, unsigned long ustk_size,
- struct task_struct *p)
+ struct task_struct *p, int return_to_kernel)
{
struct thread_info *ti = task_thread_info(p);
struct pt_regs *c_regs;
@@ -163,7 +163,7 @@ int copy_thread(unsigned long clone_flags,
p->thread.wchan = p->thread.pc;
p->thread.usp = c_usp;

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
memset(c_regs, 0, sizeof(struct pt_regs));
c_regs->a0 = c_usp; /* function */
c_regs->d0 = ustk_size; /* argument */
diff --git a/arch/nios2/kernel/process.c b/arch/nios2/kernel/process.c
index 2f8c74f..e1fe2c0 100644
--- a/arch/nios2/kernel/process.c
+++ b/arch/nios2/kernel/process.c
@@ -97,7 +97,8 @@ void flush_thread(void)
}

int copy_thread(unsigned long clone_flags,
- unsigned long usp, unsigned long arg, struct task_struct *p)
+ unsigned long usp, unsigned long arg, struct task_struct *p,
+ int return_to_kernel)
{
struct pt_regs *childregs = task_pt_regs(p);
struct pt_regs *regs;
@@ -105,7 +106,7 @@ int copy_thread(unsigned long clone_flags,
struct switch_stack *childstack =
((struct switch_stack *)childregs) - 1;

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

diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
index 7095dfe..a54fc66 100644
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -143,7 +143,7 @@ extern asmlinkage void ret_from_fork(void);

int
copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct pt_regs *userregs;
struct pt_regs *kregs;
@@ -164,7 +164,7 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
sp -= sizeof(struct pt_regs);
kregs = (struct pt_regs *)sp;

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
memset(kregs, 0, sizeof(struct pt_regs));
kregs->gpr[20] = usp; /* fn, kernel thread */
kregs->gpr[22] = arg;
diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index 809905a..7ed7eb63 100644
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -186,7 +186,8 @@ int dump_task_fpu (struct task_struct *tsk, elf_fpregset_t *r)
*/
int
copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long kthread_arg, struct task_struct *p)
+ unsigned long kthread_arg, struct task_struct *p,
+ int return_to_kernel)
{
struct pt_regs *cregs = &(p->thread.regs);
void *stack = task_stack_page(p);
@@ -197,7 +198,7 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
extern void * const ret_from_kernel_thread;
extern void * const child_return;

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
/* kernel thread */
memset(cregs, 0, sizeof(struct pt_regs));
if (!usp) /* idle thread */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3c5736e..208929f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1260,7 +1260,8 @@ 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)
+ unsigned long kthread_arg, struct task_struct *p,
+ int return_to_kernel)
{
struct pt_regs *childregs, *kregs;
extern void ret_from_fork(void);
@@ -1271,7 +1272,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
/* Copy registers */
sp -= sizeof(struct pt_regs);
childregs = (struct pt_regs *) sp;
- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
/* kernel thread */
struct thread_info *ti = (void *)task_stack_page(p);
memset(childregs, 0, sizeof(struct pt_regs));
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 2bba7df..8e8e9ef 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -118,7 +118,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
}

int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct thread_info *ti;
struct fake_frame
@@ -149,7 +149,7 @@ int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
frame->sf.gprs[9] = (unsigned long) frame;

/* Store access registers to kernel stack of new process. */
- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
/* kernel thread */
memset(&frame->childregs, 0, sizeof(struct pt_regs));
frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
diff --git a/arch/score/kernel/process.c b/arch/score/kernel/process.c
index a1519ad3..937115c 100644
--- a/arch/score/kernel/process.c
+++ b/arch/score/kernel/process.c
@@ -69,14 +69,14 @@ void flush_thread(void) {}
* set up the kernel stack and exception frames for a new process
*/
int copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct thread_info *ti = task_thread_info(p);
struct pt_regs *childregs = task_pt_regs(p);
struct pt_regs *regs = current_pt_regs();

p->thread.reg0 = (unsigned long) childregs;
- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
memset(childregs, 0, sizeof(struct pt_regs));
p->thread.reg12 = usp;
p->thread.reg13 = arg;
diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c
index 2885fc9..c8fdba3 100644
--- a/arch/sh/kernel/process_32.c
+++ b/arch/sh/kernel/process_32.c
@@ -124,7 +124,7 @@ asmlinkage void ret_from_fork(void);
asmlinkage void ret_from_kernel_thread(void);

int copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct thread_info *ti = task_thread_info(p);
struct pt_regs *childregs;
@@ -145,7 +145,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,

childregs = task_pt_regs(p);
p->thread.sp = (unsigned long) childregs;
- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
memset(childregs, 0, sizeof(struct pt_regs));
p->thread.pc = (unsigned long) ret_from_kernel_thread;
childregs->regs[4] = arg;
diff --git a/arch/sh/kernel/process_64.c b/arch/sh/kernel/process_64.c
index e2062e6..31e116a 100644
--- a/arch/sh/kernel/process_64.c
+++ b/arch/sh/kernel/process_64.c
@@ -372,7 +372,7 @@ asmlinkage void ret_from_fork(void);
asmlinkage void ret_from_kernel_thread(void);

int copy_thread(unsigned long clone_flags, unsigned long usp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct pt_regs *childregs;

@@ -390,7 +390,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
childregs = (struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1;
p->thread.sp = (unsigned long) childregs;

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
memset(childregs, 0, sizeof(struct pt_regs));
childregs->regs[2] = (unsigned long)arg;
childregs->regs[3] = (unsigned long)usp;
diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
index c5113c7..327bef8 100644
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -306,7 +306,7 @@ extern void ret_from_fork(void);
extern void ret_from_kernel_thread(void);

int copy_thread(unsigned long clone_flags, unsigned long sp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct thread_info *ti = task_thread_info(p);
struct pt_regs *childregs, *regs = current_pt_regs();
@@ -342,7 +342,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
ti->ksp = (unsigned long) new_stack;
p->thread.kregs = childregs;

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
extern int nwindows;
unsigned long psr;
memset(new_stack, 0, STACKFRAME_SZ + TRACEREG_SZ);
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 46a5964..0dcd4ba 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -617,7 +617,7 @@ asmlinkage long sparc_do_fork(unsigned long clone_flags,
* Child --> %o0 == parents pid, %o1 == 1
*/
int copy_thread(unsigned long clone_flags, unsigned long sp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct thread_info *t = task_thread_info(p);
struct pt_regs *regs = current_pt_regs();
@@ -636,7 +636,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
sizeof(struct sparc_stackf));
t->fpsaved[0] = 0;

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
memset(child_trap_frame, 0, child_stack_sz);
__thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] =
(current_pt_regs()->tstate + 1) & TSTATE_CWP;
diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c
index b5f30d3..6b24d49 100644
--- a/arch/tile/kernel/process.c
+++ b/arch/tile/kernel/process.c
@@ -100,7 +100,7 @@ void arch_release_thread_info(struct thread_info *info)
static void save_arch_state(struct thread_struct *t);

int copy_thread(unsigned long clone_flags, unsigned long sp,
- unsigned long arg, struct task_struct *p)
+ unsigned long arg, struct task_struct *p, int return_to_kernel)
{
struct pt_regs *childregs = task_pt_regs(p);
unsigned long ksp;
@@ -126,7 +126,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
/* Record the pid of the task that created this one. */
p->thread.creator_pid = current->pid;

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
/* kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
memset(&callee_regs[2], 0,
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 48af59a..40ac5bf 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -155,7 +155,8 @@ void fork_handler(void)
}

int copy_thread(unsigned long clone_flags, unsigned long sp,
- unsigned long arg, struct task_struct * p)
+ unsigned long arg, struct task_struct *p,
+ int return_to_kernel)
{
void (*handler)(void);
int kthread = current->flags & PF_KTHREAD;
@@ -163,7 +164,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,

p->thread = (struct thread_struct) INIT_THREAD;

- if (!kthread) {
+ if (!kthread && !return_to_kernel) {
memcpy(&p->thread.regs.regs, current_pt_regs(),
sizeof(p->thread.regs.regs));
PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 0);
@@ -182,15 +183,16 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,

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

- if (!kthread) {
- clear_flushed_tls(p);
+ if (kthread || return_to_kernel)
+ return ret;

- /*
- * Set a new TLS for the child thread?
- */
- if (clone_flags & CLONE_SETTLS)
- ret = arch_copy_tls(p);
- }
+ clear_flushed_tls(p);
+
+ /*
+ * Set a new TLS for the child thread?
+ */
+ if (clone_flags & CLONE_SETTLS)
+ ret = arch_copy_tls(p);

return ret;
}
diff --git a/arch/unicore32/kernel/process.c b/arch/unicore32/kernel/process.c
index b008e99..159961d 100644
--- a/arch/unicore32/kernel/process.c
+++ b/arch/unicore32/kernel/process.c
@@ -229,14 +229,14 @@ asmlinkage void ret_from_kernel_thread(void) __asm__("ret_from_kernel_thread");

int
copy_thread(unsigned long clone_flags, unsigned long stack_start,
- unsigned long stk_sz, struct task_struct *p)
+ unsigned long stk_sz, struct task_struct *p, int return_to_kernel)
{
struct thread_info *thread = task_thread_info(p);
struct pt_regs *childregs = task_pt_regs(p);

memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
thread->cpu_context.sp = (unsigned long)childregs;
- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
thread->cpu_context.pc = (unsigned long)ret_from_kernel_thread;
thread->cpu_context.r4 = stack_start;
thread->cpu_context.r5 = stk_sz;
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 9f95091..2b1862e 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -130,7 +130,8 @@ void release_thread(struct task_struct *dead_task)
}

int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
- unsigned long arg, struct task_struct *p, unsigned long tls)
+ unsigned long arg, struct task_struct *p, unsigned long tls,
+ int return_to_kernel)
{
struct pt_regs *childregs = task_pt_regs(p);
struct task_struct *tsk;
@@ -140,7 +141,7 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
p->thread.sp0 = (unsigned long) (childregs+1);
memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
/* kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
p->thread.ip = (unsigned long) ret_from_kernel_thread;
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index b9d99e0..de05bc0 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -153,7 +153,8 @@ static inline u32 read_32bit_tls(struct task_struct *t, int tls)
}

int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
- unsigned long arg, struct task_struct *p, unsigned long tls)
+ unsigned long arg, struct task_struct *p, unsigned long tls,
+ int return_to_kernel)
{
int err;
struct pt_regs *childregs;
@@ -173,7 +174,7 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
savesegment(ds, p->thread.ds);
memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));

- if (unlikely(p->flags & PF_KTHREAD)) {
+ if (unlikely(p->flags & PF_KTHREAD) || return_to_kernel) {
/* kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
childregs->sp = (unsigned long)childregs;
diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c
index 1c85323..7765634 100644
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -189,7 +189,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
*/

int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
- unsigned long thread_fn_arg, struct task_struct *p)
+ unsigned long thread_fn_arg, struct task_struct *p,
+ int return_to_kernel)
{
struct pt_regs *childregs = task_pt_regs(p);

@@ -203,7 +204,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,

p->thread.sp = (unsigned long)childregs;

- if (!(p->flags & PF_KTHREAD)) {
+ if (!(p->flags & PF_KTHREAD) && !return_to_kernel) {
struct pt_regs *regs = current_pt_regs();
unsigned long usp = usp_thread_fn ?
usp_thread_fn : regs->areg[1];
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a10494a..56401e4 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2612,18 +2612,18 @@ extern void mm_release(struct task_struct *, struct mm_struct *);

#ifdef CONFIG_HAVE_COPY_THREAD_TLS
extern int copy_thread_tls(unsigned long, unsigned long, unsigned long,
- struct task_struct *, unsigned long);
+ struct task_struct *, unsigned long, int);
#else
extern int copy_thread(unsigned long, unsigned long, unsigned long,
- struct task_struct *);
+ struct task_struct *, int);

/* Architectures that haven't opted into copy_thread_tls get the tls argument
* via pt_regs, so ignore the tls argument passed via C. */
static inline int copy_thread_tls(
unsigned long clone_flags, unsigned long sp, unsigned long arg,
- struct task_struct *p, unsigned long tls)
+ struct task_struct *p, unsigned long tls, int return_to_kernel)
{
- return copy_thread(clone_flags, sp, arg, p);
+ return copy_thread(clone_flags, sp, arg, p, return_to_kernel);
}
#endif
extern void flush_thread(void);
@@ -2644,7 +2644,8 @@ extern int do_execveat(int, struct filename *,
const char __user * const __user *,
const char __user * const __user *,
int);
-extern long _do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *, unsigned long);
+extern long _do_fork(unsigned long, unsigned long, unsigned long, int __user *,
+ int __user *, unsigned long, int);
extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *);
struct task_struct *fork_idle(int);
extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
diff --git a/kernel/fork.c b/kernel/fork.c
index 2e391c7..643a09b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1245,7 +1245,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
int __user *child_tidptr,
struct pid *pid,
int trace,
- unsigned long tls)
+ unsigned long tls,
+ int return_to_kernel)
{
int retval;
struct task_struct *p;
@@ -1451,7 +1452,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
retval = copy_io(clone_flags, p);
if (retval)
goto bad_fork_cleanup_namespaces;
- retval = copy_thread_tls(clone_flags, stack_start, stack_size, p, tls);
+ retval = copy_thread_tls(clone_flags, stack_start, stack_size, p, tls,
+ return_to_kernel);
if (retval)
goto bad_fork_cleanup_io;

@@ -1673,7 +1675,7 @@ static inline void init_idle_pids(struct pid_link *links)
struct task_struct *fork_idle(int cpu)
{
struct task_struct *task;
- task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0, 0);
+ task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0, 0, 0);
if (!IS_ERR(task)) {
init_idle_pids(task->pids);
init_idle(task, cpu);
@@ -1693,7 +1695,8 @@ long _do_fork(unsigned long clone_flags,
unsigned long stack_size,
int __user *parent_tidptr,
int __user *child_tidptr,
- unsigned long tls)
+ unsigned long tls,
+ int return_to_kernel)
{
struct task_struct *p;
int trace = 0;
@@ -1718,7 +1721,7 @@ long _do_fork(unsigned long clone_flags,
}

p = copy_process(clone_flags, stack_start, stack_size,
- child_tidptr, NULL, trace, tls);
+ child_tidptr, NULL, trace, tls, return_to_kernel);
/*
* Do this prior waking up the new thread - the thread pointer
* might get invalid after that point, if the thread exits quickly.
@@ -1769,7 +1772,7 @@ long do_fork(unsigned long clone_flags,
int __user *child_tidptr)
{
return _do_fork(clone_flags, stack_start, stack_size,
- parent_tidptr, child_tidptr, 0);
+ parent_tidptr, child_tidptr, 0, 0);
}
#endif

@@ -1779,14 +1782,14 @@ long do_fork(unsigned long clone_flags,
pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
return _do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn,
- (unsigned long)arg, NULL, NULL, 0);
+ (unsigned long)arg, NULL, NULL, 0, 0);
}

#ifdef __ARCH_WANT_SYS_FORK
SYSCALL_DEFINE0(fork)
{
#ifdef CONFIG_MMU
- return _do_fork(SIGCHLD, 0, 0, NULL, NULL, 0);
+ return _do_fork(SIGCHLD, 0, 0, NULL, NULL, 0, 0);
#else
/* can not support in nommu mode */
return -EINVAL;
@@ -1798,7 +1801,7 @@ SYSCALL_DEFINE0(fork)
SYSCALL_DEFINE0(vfork)
{
return _do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0,
- 0, NULL, NULL, 0);
+ 0, NULL, NULL, 0, 0);
}
#endif

@@ -1826,7 +1829,8 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
unsigned long, tls)
#endif
{
- return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr, tls);
+ return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr,
+ tls, 0);
}
#endif

--
1.8.5.1