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authorJonas Bonn2012-10-19 11:07:44 -0500
committerJonas Bonn2012-10-19 11:32:36 -0500
commitcbf23cf1b96819599f6a1b9658d1bf3a97c6ff15 (patch)
tree4ed2583ded570499617cc6fd9caffb4f17eddbd5 /arch/openrisc
parent287ad220cd8b5a9d29f71c78f6e4051093f051fc (diff)
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am43-linux-kernel-cbf23cf1b96819599f6a1b9658d1bf3a97c6ff15.tar.xz
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openrisc: use generic kernel_thread/kernel_execve
Signed-off-by: Jonas Bonn <jonas@southpole.se>
Diffstat (limited to 'arch/openrisc')
-rw-r--r--arch/openrisc/Kconfig2
-rw-r--r--arch/openrisc/kernel/entry.S30
-rw-r--r--arch/openrisc/kernel/process.c138
3 files changed, 68 insertions, 102 deletions
diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
index 05f2ba41ff1..e7f1a2993f7 100644
--- a/arch/openrisc/Kconfig
+++ b/arch/openrisc/Kconfig
@@ -22,6 +22,8 @@ config OPENRISC
22 select GENERIC_STRNCPY_FROM_USER 22 select GENERIC_STRNCPY_FROM_USER
23 select GENERIC_STRNLEN_USER 23 select GENERIC_STRNLEN_USER
24 select MODULES_USE_ELF_RELA 24 select MODULES_USE_ELF_RELA
25 select GENERIC_KERNEL_THREAD
26 select GENERIC_KERNEL_EXECVE
25 27
26config MMU 28config MMU
27 def_bool y 29 def_bool y
diff --git a/arch/openrisc/kernel/entry.S b/arch/openrisc/kernel/entry.S
index 374e63e7c9f..dce86aef8ab 100644
--- a/arch/openrisc/kernel/entry.S
+++ b/arch/openrisc/kernel/entry.S
@@ -894,6 +894,16 @@ ENTRY(ret_from_fork)
894 l.jal schedule_tail 894 l.jal schedule_tail
895 l.nop 895 l.nop
896 896
897 /* Check if we are a kernel thread */
898 l.sfeqi r20,0
899 l.bf 1f
900 l.nop
901
902 /* ...we are a kernel thread so invoke the requested callback */
903 l.jalr r20
904 l.or r3,r22,r0
905
9061:
897 /* _syscall_returns expect r11 to contain return value */ 907 /* _syscall_returns expect r11 to contain return value */
898 l.lwz r11,PT_GPR11(r1) 908 l.lwz r11,PT_GPR11(r1)
899 909
@@ -915,26 +925,6 @@ ENTRY(ret_from_fork)
915 l.j _syscall_return 925 l.j _syscall_return
916 l.nop 926 l.nop
917 927
918/* Since syscalls don't save call-clobbered registers, the args to
919 * kernel_thread_helper will need to be passed through callee-saved
920 * registers and copied to the parameter registers when the thread
921 * begins running.
922 *
923 * See arch/openrisc/kernel/process.c:
924 * The args are passed as follows:
925 * arg1 (r3) : passed in r20
926 * arg2 (r4) : passed in r22
927 */
928
929ENTRY(_kernel_thread_helper)
930 l.or r3,r20,r0
931 l.or r4,r22,r0
932 l.movhi r31,hi(kernel_thread_helper)
933 l.ori r31,r31,lo(kernel_thread_helper)
934 l.jr r31
935 l.nop
936
937
938/* ========================================================[ switch ] === */ 928/* ========================================================[ switch ] === */
939 929
940/* 930/*
diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
index ad26d5af264..a0f467e438f 100644
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -109,65 +109,82 @@ void release_thread(struct task_struct *dead_task)
109 */ 109 */
110extern asmlinkage void ret_from_fork(void); 110extern asmlinkage void ret_from_fork(void);
111 111
112/*
113 * copy_thread
114 * @clone_flags: flags
115 * @usp: user stack pointer or fn for kernel thread
116 * @arg: arg to fn for kernel thread; always NULL for userspace thread
117 * @p: the newly created task
118 * @regs: CPU context to copy for userspace thread; always NULL for kthread
119 *
120 * At the top of a newly initialized kernel stack are two stacked pt_reg
121 * structures. The first (topmost) is the userspace context of the thread.
122 * The second is the kernelspace context of the thread.
123 *
124 * A kernel thread will not be returning to userspace, so the topmost pt_regs
125 * struct can be uninitialized; it _does_ need to exist, though, because
126 * a kernel thread can become a userspace thread by doing a kernel_execve, in
127 * which case the topmost context will be initialized and used for 'returning'
128 * to userspace.
129 *
130 * The second pt_reg struct needs to be initialized to 'return' to
131 * ret_from_fork. A kernel thread will need to set r20 to the address of
132 * a function to call into (with arg in r22); userspace threads need to set
133 * r20 to NULL in which case ret_from_fork will just continue a return to
134 * userspace.
135 *
136 * A kernel thread 'fn' may return; this is effectively what happens when
137 * kernel_execve is called. In that case, the userspace pt_regs must have
138 * been initialized (which kernel_execve takes care of, see start_thread
139 * below); ret_from_fork will then continue its execution causing the
140 * 'kernel thread' to return to userspace as a userspace thread.
141 */
142
112int 143int
113copy_thread(unsigned long clone_flags, unsigned long usp, 144copy_thread(unsigned long clone_flags, unsigned long usp,
114 unsigned long unused, struct task_struct *p, struct pt_regs *regs) 145 unsigned long arg, struct task_struct *p, struct pt_regs *regs)
115{ 146{
116 struct pt_regs *childregs; 147 struct pt_regs *userregs;
117 struct pt_regs *kregs; 148 struct pt_regs *kregs;
118 unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE; 149 unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
119 struct thread_info *ti;
120 unsigned long top_of_kernel_stack; 150 unsigned long top_of_kernel_stack;
121 151
122 top_of_kernel_stack = sp; 152 top_of_kernel_stack = sp;
123 153
124 p->set_child_tid = p->clear_child_tid = NULL; 154 p->set_child_tid = p->clear_child_tid = NULL;
125 155
126 /* Copy registers */ 156 /* Locate userspace context on stack... */
127 /* redzone */ 157 sp -= STACK_FRAME_OVERHEAD; /* redzone */
128 sp -= STACK_FRAME_OVERHEAD;
129 sp -= sizeof(struct pt_regs); 158 sp -= sizeof(struct pt_regs);
130 childregs = (struct pt_regs *)sp; 159 userregs = (struct pt_regs *) sp;
131 160
132 /* Copy parent registers */ 161 /* ...and kernel context */
133 *childregs = *regs; 162 sp -= STACK_FRAME_OVERHEAD; /* redzone */
163 sp -= sizeof(struct pt_regs);
164 kregs = (struct pt_regs *)sp;
134 165
135 if ((childregs->sr & SPR_SR_SM) == 1) { 166 if (unlikely(p->flags & PF_KTHREAD)) {
136 /* for kernel thread, set `current_thread_info' 167 memset(kregs, 0, sizeof(struct pt_regs));
137 * and stackptr in new task 168 kregs->gpr[20] = usp; /* fn, kernel thread */
138 */ 169 kregs->gpr[22] = arg;
139 childregs->sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
140 childregs->gpr[10] = (unsigned long)task_thread_info(p);
141 } else { 170 } else {
142 childregs->sp = usp; 171 *userregs = *regs;
143 }
144
145 childregs->gpr[11] = 0; /* Result from fork() */
146 172
147 /* 173 userregs->sp = usp;
148 * The way this works is that at some point in the future 174 userregs->gpr[11] = 0; /* Result from fork() */
149 * some task will call _switch to switch to the new task.
150 * That will pop off the stack frame created below and start
151 * the new task running at ret_from_fork. The new task will
152 * do some house keeping and then return from the fork or clone
153 * system call, using the stack frame created above.
154 */
155 /* redzone */
156 sp -= STACK_FRAME_OVERHEAD;
157 sp -= sizeof(struct pt_regs);
158 kregs = (struct pt_regs *)sp;
159 175
160 ti = task_thread_info(p); 176 kregs->gpr[20] = 0; /* Userspace thread */
161 ti->ksp = sp; 177 }
162 178
163 /* kregs->sp must store the location of the 'pre-switch' kernel stack 179 /*
164 * pointer... for a newly forked process, this is simply the top of 180 * _switch wants the kernel stack page in pt_regs->sp so that it
165 * the kernel stack. 181 * can restore it to thread_info->ksp... see _switch for details.
166 */ 182 */
167 kregs->sp = top_of_kernel_stack; 183 kregs->sp = top_of_kernel_stack;
168 kregs->gpr[10] = (unsigned long)task_thread_info(p);
169 kregs->gpr[9] = (unsigned long)ret_from_fork; 184 kregs->gpr[9] = (unsigned long)ret_from_fork;
170 185
186 task_thread_info(p)->ksp = (unsigned long)kregs;
187
171 return 0; 188 return 0;
172} 189}
173 190
@@ -176,16 +193,14 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
176 */ 193 */
177void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp) 194void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
178{ 195{
179 unsigned long sr = regs->sr & ~SPR_SR_SM; 196 unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;
180 197
181 set_fs(USER_DS); 198 set_fs(USER_DS);
182 memset(regs->gpr, 0, sizeof(regs->gpr)); 199 memset(regs, 0, sizeof(struct pt_regs));
183 200
184 regs->pc = pc; 201 regs->pc = pc;
185 regs->sr = sr; 202 regs->sr = sr;
186 regs->sp = sp; 203 regs->sp = sp;
187
188/* printk("start thread, ksp = %lx\n", current_thread_info()->ksp);*/
189} 204}
190 205
191/* Fill in the fpu structure for a core dump. */ 206/* Fill in the fpu structure for a core dump. */
@@ -236,31 +251,6 @@ void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
236 dest[35] = 0; 251 dest[35] = 0;
237} 252}
238 253
239extern void _kernel_thread_helper(void);
240
241void __noreturn kernel_thread_helper(int (*fn) (void *), void *arg)
242{
243 do_exit(fn(arg));
244}
245
246/*
247 * Create a kernel thread.
248 */
249int kernel_thread(int (*fn) (void *), void *arg, unsigned long flags)
250{
251 struct pt_regs regs;
252
253 memset(&regs, 0, sizeof(regs));
254
255 regs.gpr[20] = (unsigned long)fn;
256 regs.gpr[22] = (unsigned long)arg;
257 regs.sr = mfspr(SPR_SR);
258 regs.pc = (unsigned long)_kernel_thread_helper;
259
260 return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
261 0, &regs, 0, NULL, NULL);
262}
263
264/* 254/*
265 * sys_execve() executes a new program. 255 * sys_execve() executes a new program.
266 */ 256 */
@@ -291,19 +281,3 @@ unsigned long get_wchan(struct task_struct *p)
291 281
292 return 0; 282 return 0;
293} 283}
294
295int kernel_execve(const char *filename, char *const argv[], char *const envp[])
296{
297 register long __res asm("r11") = __NR_execve;
298 register long __a asm("r3") = (long)(filename);
299 register long __b asm("r4") = (long)(argv);
300 register long __c asm("r5") = (long)(envp);
301 __asm__ volatile ("l.sys 1"
302 : "=r" (__res), "=r"(__a), "=r"(__b), "=r"(__c)
303 : "0"(__res), "1"(__a), "2"(__b), "3"(__c)
304 : "r6", "r7", "r8", "r12", "r13", "r15",
305 "r17", "r19", "r21", "r23", "r25", "r27",
306 "r29", "r31");
307 __asm__ volatile ("l.nop");
308 return __res;
309}