From: Ingo Molnar <[EMAIL PROTECTED]> add the create_async_thread() way of creating kernel threads: these threads first execute a kernel function and when they return from it they execute user-space.
An architecture must implement this interface before it can turn CONFIG_ASYNC_SUPPORT on. Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]> Signed-off-by: Arjan van de Ven <[EMAIL PROTECTED]> --- arch/i386/kernel/entry.S | 25 +++++++++++++++++++++++++ arch/i386/kernel/process.c | 31 +++++++++++++++++++++++++++++++ include/asm-i386/processor.h | 17 +++++++++++++++++ include/asm-i386/unistd.h | 10 ++++++++++ 4 files changed, 83 insertions(+) Index: linux/arch/i386/kernel/entry.S =================================================================== --- linux.orig/arch/i386/kernel/entry.S +++ linux/arch/i386/kernel/entry.S @@ -1034,6 +1034,31 @@ ENTRY(kernel_thread_helper) CFI_ENDPROC ENDPROC(kernel_thread_helper) +ENTRY(async_thread_helper) + CFI_STARTPROC + /* + * Allocate space on the stack for pt-regs. + * sizeof(struct pt_regs) == 64, and we've got 8 bytes on the + * kernel stack already: + */ + subl $64-8, %esp + CFI_ADJUST_CFA_OFFSET 64-8 + movl %edx,%eax + push %edx + CFI_ADJUST_CFA_OFFSET 4 + call *%ebx + addl $4, %esp + CFI_ADJUST_CFA_OFFSET -4 + + movl %eax, PT_EAX(%esp) + + GET_THREAD_INFO(%ebp) + + jmp syscall_exit + CFI_ENDPROC +ENDPROC(async_thread_helper) + + .section .rodata,"a" #include "syscall_table.S" Index: linux/arch/i386/kernel/process.c =================================================================== --- linux.orig/arch/i386/kernel/process.c +++ linux/arch/i386/kernel/process.c @@ -355,6 +355,37 @@ int kernel_thread(int (*fn)(void *), voi EXPORT_SYMBOL(kernel_thread); /* + * This gets run with %ebx containing the + * function to call, and %edx containing + * the "args". + */ +extern void async_thread_helper(void); + +/* + * Create an async thread + */ +int create_async_thread(long (*fn)(void *), void * arg, unsigned long flags) +{ + struct pt_regs regs; + + memset(®s, 0, sizeof(regs)); + + regs.ebx = (unsigned long) fn; + regs.edx = (unsigned long) arg; + + regs.xds = __USER_DS; + regs.xes = __USER_DS; + regs.xfs = __KERNEL_PDA; + regs.orig_eax = -1; + regs.eip = (unsigned long) async_thread_helper; + regs.xcs = __KERNEL_CS | get_kernel_rpl(); + regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2; + + /* Ok, create the new task.. */ + return do_fork(flags, 0, ®s, 0, NULL, NULL); +} + +/* * Free current thread data structures etc.. */ void exit_thread(void) Index: linux/include/asm-i386/processor.h =================================================================== --- linux.orig/include/asm-i386/processor.h +++ linux/include/asm-i386/processor.h @@ -472,6 +472,11 @@ extern void prepare_to_copy(struct task_ */ extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags); +/* + * create an async thread: + */ +extern int create_async_thread(long (*fn)(void *), void * arg, unsigned long flags); + extern unsigned long thread_saved_pc(struct task_struct *tsk); void show_trace(struct task_struct *task, struct pt_regs *regs, unsigned long *stack); @@ -504,6 +509,18 @@ unsigned long get_wchan(struct task_stru #define KSTK_EIP(task) (task_pt_regs(task)->eip) #define KSTK_ESP(task) (task_pt_regs(task)->esp) +/* + * Register access methods for async syscall support. + * + * Note, task_stack_reg() must not be an lvalue, hence this macro: + */ +#define task_stack_reg(t) \ + ({ unsigned long __esp = task_pt_regs(t)->esp; __esp; }) +#define set_task_stack_reg(t, new_stack) \ + do { task_pt_regs(t)->esp = (new_stack); } while (0) +#define task_ip_reg(t) task_pt_regs(t)->eip +#define task_ret_reg(t) task_pt_regs(t)->eax + struct microcode_header { unsigned int hdrver; Index: linux/include/asm-i386/unistd.h =================================================================== --- linux.orig/include/asm-i386/unistd.h +++ linux/include/asm-i386/unistd.h @@ -1,6 +1,8 @@ #ifndef _ASM_I386_UNISTD_H_ #define _ASM_I386_UNISTD_H_ +#include <linux/linkage.h> + /* * This file contains the system call numbers. */ @@ -330,6 +332,14 @@ #define NR_syscalls 320 +#ifndef __ASSEMBLY__ + +typedef asmlinkage long (*syscall_fn_t)(long, long, long, long, long, long); + +extern syscall_fn_t sys_call_table[NR_syscalls]; + +#endif + #define __ARCH_WANT_IPC_PARSE_VERSION #define __ARCH_WANT_OLD_READDIR #define __ARCH_WANT_OLD_STAT - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/