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tile: support GENERIC_KERNEL_THREAD and GENERIC_KERNEL_EXECVE

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Also provide an optimized current_pt_regs() while we're at it.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Chris Metcalf 2012-10-19 16:25:12 -04:00 committed by Al Viro
parent 733deca197
commit 0f8b983812
6 changed files with 75 additions and 76 deletions
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2
arch/tile/Kconfig
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@ -21,6 +21,8 @@ config TILE
select ARCH_HAVE_NMI_SAFE_CMPXCHG
select GENERIC_CLOCKEVENTS
select MODULES_USE_ELF_RELA
select GENERIC_KERNEL_THREAD
select GENERIC_KERNEL_EXECVE
# FIXME: investigate whether we need/want these options.
# select HAVE_IOREMAP_PROT

5
arch/tile/include/asm/switch_to.h
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@ -68,7 +68,10 @@ extern unsigned long get_switch_to_pc(void);
/* Support function for forking a new task. */
void ret_from_fork(void);
/* Called from ret_from_fork() when a new process starts up. */
/* Support function for forking a new kernel thread. */
void ret_from_kernel_thread(void *fn, void *arg);
/* Called from ret_from_xxx() when a new process starts up. */
struct task_struct *sim_notify_fork(struct task_struct *prev);
#endif /* !__ASSEMBLY__ */

11
arch/tile/kernel/entry.S
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@ -27,17 +27,6 @@ STD_ENTRY(current_text_addr)
{ move r0, lr; jrp lr }
STD_ENDPROC(current_text_addr)
/*
* Implement execve(). The i386 code has a note that forking from kernel
* space results in no copy on write until the execve, so we should be
* careful not to write to the stack here.
*/
STD_ENTRY(kernel_execve)
moveli TREG_SYSCALL_NR_NAME, __NR_execve
swint1
jrp lr
STD_ENDPROC(kernel_execve)
/*
* We don't run this function directly, but instead copy it to a page
* we map into every user process. See vdso_setup().

15
arch/tile/kernel/intvec_32.S
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@ -1291,6 +1291,21 @@ STD_ENTRY(ret_from_fork)
}
STD_ENDPROC(ret_from_fork)
STD_ENTRY(ret_from_kernel_thread)
jal sim_notify_fork
jal schedule_tail
FEEDBACK_REENTER(ret_from_fork)
{
move r0, r31
jalr r30
}
FEEDBACK_REENTER(ret_from_kernel_thread)
{
movei r30, 0 /* not an NMI */
j .Lresume_userspace /* jump into middle of interrupt_return */
}
STD_ENDPROC(ret_from_kernel_thread)
/*
* Code for ill interrupt.
*/

15
arch/tile/kernel/intvec_64.S
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@ -1150,6 +1150,21 @@ STD_ENTRY(ret_from_fork)
}
STD_ENDPROC(ret_from_fork)
STD_ENTRY(ret_from_kernel_thread)
jal sim_notify_fork
jal schedule_tail
FEEDBACK_REENTER(ret_from_fork)
{
move r0, r31
jalr r30
}
FEEDBACK_REENTER(ret_from_kernel_thread)
{
movei r30, 0 /* not an NMI */
j .Lresume_userspace /* jump into middle of interrupt_return */
}
STD_ENDPROC(ret_from_kernel_thread)
/* Various stub interrupt handlers and syscall handlers */
STD_ENTRY_LOCAL(_kernel_double_fault)

103
arch/tile/kernel/process.c
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@ -157,24 +157,44 @@ 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 stack_size,
unsigned long arg,
struct task_struct *p, struct pt_regs *regs)
{
struct pt_regs *childregs;
struct pt_regs *childregs = task_pt_regs(p);
unsigned long ksp;
unsigned long *callee_regs;
/*
* When creating a new kernel thread we pass sp as zero.
* Assign it to a reasonable value now that we have the stack.
* Set up the stack and stack pointer appropriately for the
* new child to find itself woken up in __switch_to().
* The callee-saved registers must be on the stack to be read;
* the new task will then jump to assembly support to handle
* calling schedule_tail(), etc., and (for userspace tasks)
* returning to the context set up in the pt_regs.
*/
if (sp == 0 && regs->ex1 == PL_ICS_EX1(KERNEL_PL, 0))
sp = KSTK_TOP(p);
ksp = (unsigned long) childregs;
ksp -= C_ABI_SAVE_AREA_SIZE; /* interrupt-entry save area */
((long *)ksp)[0] = ((long *)ksp)[1] = 0;
ksp -= CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long);
callee_regs = (unsigned long *)ksp;
ksp -= C_ABI_SAVE_AREA_SIZE; /* __switch_to() save area */
((long *)ksp)[0] = ((long *)ksp)[1] = 0;
p->thread.ksp = ksp;
/*
* Do not clone step state from the parent; each thread
* must make its own lazily.
*/
task_thread_info(p)->step_state = NULL;
/* Record the pid of the task that created this one. */
p->thread.creator_pid = current->pid;
if (unlikely(!regs)) {
/* kernel thread */
memset(childregs, 0, sizeof(struct pt_regs));
memset(&callee_regs[2], 0,
(CALLEE_SAVED_REGS_COUNT - 2) * sizeof(unsigned long));
callee_regs[0] = sp; /* r30 = function */
callee_regs[1] = arg; /* r31 = arg */
childregs->ex1 = PL_ICS_EX1(KERNEL_PL, 0);
p->thread.pc = (unsigned long) ret_from_kernel_thread;
return 0;
}
/*
* Start new thread in ret_from_fork so it schedules properly
@ -182,20 +202,24 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
*/
p->thread.pc = (unsigned long) ret_from_fork;
/*
* Do not clone step state from the parent; each thread
* must make its own lazily.
*/
task_thread_info(p)->step_state = NULL;
/* Save user stack top pointer so we can ID the stack vm area later. */
p->thread.usp0 = sp;
/* Record the pid of the process that created this one. */
p->thread.creator_pid = current->pid;
/*
* Copy the registers onto the kernel stack so the
* return-from-interrupt code will reload it into registers.
*/
childregs = task_pt_regs(p);
*childregs = *regs;
childregs->regs[0] = 0; /* return value is zero */
childregs->sp = sp; /* override with new user stack pointer */
memcpy(callee_regs, &regs->regs[CALLEE_SAVED_FIRST_REG],
CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long));
/*
* If CLONE_SETTLS is set, set "tp" in the new task to "r4",
@ -204,24 +228,6 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
if (clone_flags & CLONE_SETTLS)
childregs->tp = regs->regs[4];
/*
* Copy the callee-saved registers from the passed pt_regs struct
* into the context-switch callee-saved registers area.
* This way when we start the interrupt-return sequence, the
* callee-save registers will be correctly in registers, which
* is how we assume the compiler leaves them as we start doing
* the normal return-from-interrupt path after calling C code.
* Zero out the C ABI save area to mark the top of the stack.
*/
ksp = (unsigned long) childregs;
ksp -= C_ABI_SAVE_AREA_SIZE; /* interrupt-entry save area */
((long *)ksp)[0] = ((long *)ksp)[1] = 0;
ksp -= CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long);
memcpy((void *)ksp, &regs->regs[CALLEE_SAVED_FIRST_REG],
CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long));
ksp -= C_ABI_SAVE_AREA_SIZE; /* __switch_to() save area */
((long *)ksp)[0] = ((long *)ksp)[1] = 0;
p->thread.ksp = ksp;
#if CHIP_HAS_TILE_DMA()
/*
@ -650,37 +656,6 @@ unsigned long get_wchan(struct task_struct *p)
return 0;
}
/*
* We pass in lr as zero (cleared in kernel_thread) and the caller
* part of the backtrace ABI on the stack also zeroed (in copy_thread)
* so that backtraces will stop with this function.
* Note that we don't use r0, since copy_thread() clears it.
*/
static void start_kernel_thread(int dummy, int (*fn)(int), int arg)
{
do_exit(fn(arg));
}
/*
* Create a kernel thread
*/
int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
struct pt_regs regs;
memset(&regs, 0, sizeof(regs));
regs.ex1 = PL_ICS_EX1(KERNEL_PL, 0); /* run at kernel PL, no ICS */
regs.pc = (long) start_kernel_thread;
regs.flags = PT_FLAGS_CALLER_SAVES; /* need to restore r1 and r2 */
regs.regs[1] = (long) fn; /* function pointer */
regs.regs[2] = (long) arg; /* parameter register */
/* Ok, create the new process.. */
return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs,
0, NULL, NULL);
}
EXPORT_SYMBOL(kernel_thread);
/* Flush thread state. */
void flush_thread(void)
{