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authorAl Viro <viro@zeniv.linux.org.uk>2012-10-18 22:45:24 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2012-10-23 22:05:21 -0400
commit995218555433b260b58059802e1c01f35b4cd860 (patch)
tree801d384bdc54c104049eee2bf007c02d639a34ce /arch/hexagon/kernel
parentddffeb8c4d0331609ef2581d84de4d763607bd37 (diff)
downloadvexpress-lsk-995218555433b260b58059802e1c01f35b4cd860.tar.gz
hexagon: kernel_thread()/kernel_execve() conversion
introduce sane current_pt_regs(), use it in syscalls where needed. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'arch/hexagon/kernel')
-rw-r--r--arch/hexagon/kernel/process.c102
-rw-r--r--arch/hexagon/kernel/signal.c4
-rw-r--r--arch/hexagon/kernel/syscall.c27
-rw-r--r--arch/hexagon/kernel/vm_entry.S4
4 files changed, 40 insertions, 97 deletions
diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c
index af51de63b83..8a016f7e394 100644
--- a/arch/hexagon/kernel/process.c
+++ b/arch/hexagon/kernel/process.c
@@ -26,33 +26,6 @@
#include <linux/slab.h>
/*
- * Kernel thread creation. The desired kernel function is "wrapped"
- * in the kernel_thread_helper function, which does cleanup
- * afterwards.
- */
-static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *))
-{
- do_exit(fn(arg));
-}
-
-int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
-{
- struct pt_regs regs;
-
- memset(&regs, 0, sizeof(regs));
- /*
- * Yes, we're exploting illicit knowledge of the ABI here.
- */
- regs.r00 = (unsigned long) arg;
- regs.r01 = (unsigned long) fn;
- pt_set_elr(&regs, (unsigned long)kernel_thread_helper);
- pt_set_kmode(&regs);
-
- return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
-}
-EXPORT_SYMBOL(kernel_thread);
-
-/*
* Program thread launch. Often defined as a macro in processor.h,
* but we're shooting for a small footprint and it's not an inner-loop
* performance-critical operation.
@@ -114,7 +87,7 @@ 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 unused, struct task_struct *p,
+ unsigned long arg, struct task_struct *p,
struct pt_regs *regs)
{
struct thread_info *ti = task_thread_info(p);
@@ -125,61 +98,50 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
childregs = (struct pt_regs *) (((unsigned long) ti + THREAD_SIZE) -
sizeof(*childregs));
- memcpy(childregs, regs, sizeof(*childregs));
ti->regs = childregs;
/*
* Establish kernel stack pointer and initial PC for new thread
+ * Note that unlike the usual situation, we do not copy the
+ * parent's callee-saved here; those are in pt_regs and whatever
+ * we leave here will be overridden on return to userland.
*/
ss = (struct hexagon_switch_stack *) ((unsigned long) childregs -
sizeof(*ss));
ss->lr = (unsigned long)ret_from_fork;
p->thread.switch_sp = ss;
-
- /* If User mode thread, set pt_reg stack pointer as per parameter */
- if (user_mode(childregs)) {
- pt_set_rte_sp(childregs, usp);
-
- /* Child sees zero return value */
- childregs->r00 = 0;
-
- /*
- * The clone syscall has the C signature:
- * int [r0] clone(int flags [r0],
- * void *child_frame [r1],
- * void *parent_tid [r2],
- * void *child_tid [r3],
- * void *thread_control_block [r4]);
- * ugp is used to provide TLS support.
- */
- if (clone_flags & CLONE_SETTLS)
- childregs->ugp = childregs->r04;
-
- /*
- * Parent sees new pid -- not necessary, not even possible at
- * this point in the fork process
- * Might also want to set things like ti->addr_limit
- */
- } else {
- /*
- * If kernel thread, resume stack is kernel stack base.
- * Note that this is pointer arithmetic on pt_regs *
- */
- pt_set_rte_sp(childregs, (unsigned long)(childregs + 1));
- /*
- * We need the current thread_info fast path pointer
- * set up in pt_regs. The register to be used is
- * parametric for assembler code, but the mechanism
- * doesn't drop neatly into C. Needs to be fixed.
- */
- childregs->THREADINFO_REG = (unsigned long) ti;
+ if (unlikely(p->flags & PF_KTHREAD)) {
+ memset(childregs, 0, sizeof(struct pt_regs));
+ /* r24 <- fn, r25 <- arg */
+ ss->r2524 = usp | ((u64)arg << 32);
+ pt_set_kmode(childregs);
+ return 0;
}
+ memcpy(childregs, regs, sizeof(*childregs));
+ ss->r2524 = 0;
+
+ pt_set_rte_sp(childregs, usp);
+
+ /* Child sees zero return value */
+ childregs->r00 = 0;
+
+ /*
+ * The clone syscall has the C signature:
+ * int [r0] clone(int flags [r0],
+ * void *child_frame [r1],
+ * void *parent_tid [r2],
+ * void *child_tid [r3],
+ * void *thread_control_block [r4]);
+ * ugp is used to provide TLS support.
+ */
+ if (clone_flags & CLONE_SETTLS)
+ childregs->ugp = childregs->r04;
/*
- * thread_info pointer is pulled out of task_struct "stack"
- * field on switch_to.
+ * Parent sees new pid -- not necessary, not even possible at
+ * this point in the fork process
+ * Might also want to set things like ti->addr_limit
*/
- p->stack = (void *)ti;
return 0;
}
diff --git a/arch/hexagon/kernel/signal.c b/arch/hexagon/kernel/signal.c
index 1ea16bec7b9..28b9e261776 100644
--- a/arch/hexagon/kernel/signal.c
+++ b/arch/hexagon/kernel/signal.c
@@ -249,14 +249,14 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
*/
asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
{
- struct pt_regs *regs = current_thread_info()->regs;
+ struct pt_regs *regs = current_pt_regs();
return do_sigaltstack(uss, uoss, regs->r29);
}
asmlinkage int sys_rt_sigreturn(void)
{
- struct pt_regs *regs = current_thread_info()->regs;
+ struct pt_regs *regs = current_pt_regs();
struct rt_sigframe __user *frame;
sigset_t blocked;
diff --git a/arch/hexagon/kernel/syscall.c b/arch/hexagon/kernel/syscall.c
index 25a9bfe3445..120f1a5e9f3 100644
--- a/arch/hexagon/kernel/syscall.c
+++ b/arch/hexagon/kernel/syscall.c
@@ -39,7 +39,7 @@ asmlinkage int sys_execve(char __user *ufilename,
const char __user *const __user *argv,
const char __user *const __user *envp)
{
- struct pt_regs *pregs = current_thread_info()->regs;
+ struct pt_regs *pregs = current_pt_regs();
struct filename *filename;
int retval;
@@ -57,33 +57,10 @@ asmlinkage int sys_execve(char __user *ufilename,
asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
unsigned long parent_tidp, unsigned long child_tidp)
{
- struct pt_regs *pregs = current_thread_info()->regs;
+ struct pt_regs *pregs = current_pt_regs();
if (!newsp)
newsp = pregs->SP;
return do_fork(clone_flags, newsp, pregs, 0, (int __user *)parent_tidp,
(int __user *)child_tidp);
}
-
-/*
- * Do a system call from the kernel, so as to have a proper pt_regs
- * and recycle the sys_execvpe infrustructure.
- */
-int kernel_execve(const char *filename,
- const char *const argv[], const char *const envp[])
-{
- register unsigned long __a0 asm("r0") = (unsigned long) filename;
- register unsigned long __a1 asm("r1") = (unsigned long) argv;
- register unsigned long __a2 asm("r2") = (unsigned long) envp;
- int retval;
-
- __asm__ volatile(
- " R6 = #%4;\n"
- " trap0(#1);\n"
- " %0 = R0;\n"
- : "=r" (retval)
- : "r" (__a0), "r" (__a1), "r" (__a2), "i" (__NR_execve)
- );
-
- return retval;
-}
diff --git a/arch/hexagon/kernel/vm_entry.S b/arch/hexagon/kernel/vm_entry.S
index 5b99066cbc8..1a7fcf50209 100644
--- a/arch/hexagon/kernel/vm_entry.S
+++ b/arch/hexagon/kernel/vm_entry.S
@@ -266,4 +266,8 @@ _K_enter_machcheck:
.globl ret_from_fork
ret_from_fork:
call schedule_tail
+ P0 = cmp.eq(R24, #0);
+ if P0 jump return_from_syscall
+ R0 = R25;
+ callr R24
jump return_from_syscall