[PATCH 08/24] C6X: process management

Mark Salter
2011-08-08T21:44:48Z

Signed-off-by: Mark Salter <msalter@redhat.com>
---
arch/c6x/include/asm/processor.h | 132 ++++++++++++++++++
arch/c6x/include/asm/thread_info.h | 121 ++++++++++++++++
arch/c6x/kernel/process.c | 264 ++++++++++++++++++++++++++++++++++++
arch/c6x/kernel/switch_to.S | 74 ++++++++++
4 files changed, 591 insertions(+), 0 deletions(-)
create mode 100644 arch/c6x/include/asm/processor.h
create mode 100644 arch/c6x/include/asm/thread_info.h
create mode 100644 arch/c6x/kernel/process.c
create mode 100644 arch/c6x/kernel/switch_to.S

diff --git a/arch/c6x/include/asm/processor.h b/arch/c6x/include/asm/processor.h
new file mode 100644
index 0000000..8154c4e
--- /dev/null
+++ b/arch/c6x/include/asm/processor.h
@@ -0,0 +1,132 @@
+/*
+ * Port on Texas Instruments TMS320C6x architecture
+ *
+ * Copyright (C) 2004, 2009, 2010, 2011 Texas Instruments Incorporated
+ * Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
+ *
+ * Updated for 2.6.34: Mark Salter <msalter@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef _ASM_C6X_PROCESSOR_H
+#define _ASM_C6X_PROCESSOR_H
+
+#include <asm/ptrace.h>
+#include <asm/page.h>
+#include <asm/current.h>
+
+/*
+ * Default implementation of macro that returns current
+ * instruction pointer ("program counter").
+ */
+#define current_text_addr() \
+({ \
+ void *__pc; \
+ asm("mvc .S2 pce1,%0\n" : "=b"(__pc)); \
+ __pc; \
+})
+
+/*
+ * User space process size. This is mostly meaningless for NOMMU
+ * but some C6X processors may have RAM addresses up to 0xFFFFFFFF.
+ * Since calls like mmap() can return an address or an error, we
+ * have to allow room for error returns when code does something
+ * like:
+ *
+ * addr = do_mmap(...)
+ * if ((unsigned long)addr >= TASK_SIZE)
+ * ... its an error code, not an address ...
+ *
+ * Here, we allow for 4096 error codes which means we really can't
+ * use the last 4K page on systems with RAM extending all the way
+ * to the end of the 32-bit address space.
+ */
+#define TASK_SIZE 0xFFFFF000
+
+/*
+ * This decides where the kernel will search for a free chunk of vm
+ * space during mmap's. We won't be using it
+ */
+#define TASK_UNMAPPED_BASE 0
+
+struct thread_struct {
+ unsigned long long b15_14;
+ unsigned long long a15_14;
+ unsigned long long b13_12;
+ unsigned long long a13_12;
+ unsigned long long b11_10;
+ unsigned long long a11_10;
+ unsigned long long ricl_icl;
+ unsigned long usp; /* user stack pointer */
+ unsigned long pc; /* kernel pc */
+ unsigned long wchan;
+};
+
+#define INIT_THREAD \
+{ \
+ .usp = 0, \
+ .wchan = 0, \
+}
+
+#define INIT_MMAP { \
+ &init_mm, 0, 0, NULL, PAGE_SHARED, VM_READ | VM_WRITE | VM_EXEC, 1, \
+ NULL, NULL }
+
+#define task_pt_regs(task) \
+ ((struct pt_regs *)(THREAD_START_SP + task_stack_page(task)) - 1)
+
+#define alloc_kernel_stack() __get_free_page(GFP_KERNEL)
+#define free_kernel_stack(page) free_page((page))
+
+
+/* Forward declaration, a strange C thing */
+struct task_struct;
+
+extern void start_thread(struct pt_regs *regs, unsigned int pc,
+ unsigned long usp);
+
+/* Free all resources held by a thread. */
+static inline void release_thread(struct task_struct *dead_task)
+{
+}
+
+/* Prepare to copy thread state - unlazy all lazy status */
+#define prepare_to_copy(tsk) do { } while (0)
+
+extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
+
+#define copy_segments(tsk, mm) do { } while (0)
+#define release_segments(mm) do { } while (0)
+
+/*
+ * saved PC of a blocked thread.
+ */
+#define thread_saved_pc(tsk) (task_pt_regs(tsk)->pc)
+
+/*
+ * saved kernel SP and DP of a blocked thread.
+ */
+#ifdef _BIG_ENDIAN
+#define thread_saved_ksp(tsk) \
+ (*(unsigned long *)&(tsk)->thread.b15_14)
+#define thread_saved_dp(tsk) \
+ (*(((unsigned long *)&(tsk)->thread.b15_14) + 1))
+#else
+#define thread_saved_ksp(tsk) \
+ (*(((unsigned long *)&(tsk)->thread.b15_14) + 1))
+#define thread_saved_dp(tsk) \
+ (*(unsigned long *)&(tsk)->thread.b15_14)
+#endif
+
+extern unsigned long get_wchan(struct task_struct *p);
+
+#define KSTK_EIP(tsk) (task_pt_regs(task)->pc)
+#define KSTK_ESP(tsk) (task_pt_regs(task)->sp)
+
+#define cpu_relax() do { } while (0)
+
+extern const struct seq_operations cpuinfo_op;
+
+#endif /* ASM_C6X_PROCESSOR_H */
diff --git a/arch/c6x/include/asm/thread_info.h b/arch/c6x/include/asm/thread_info.h
new file mode 100644
index 0000000..fd99148
--- /dev/null
+++ b/arch/c6x/include/asm/thread_info.h
@@ -0,0 +1,121 @@
+/*
+ * Port on Texas Instruments TMS320C6x architecture
+ *
+ * Copyright (C) 2004, 2009, 2010, 2011 Texas Instruments Incorporated
+ * Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
+ *
+ * Updated for 2.6.3x: Mark Salter <msalter@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef _ASM_C6X_THREAD_INFO_H
+#define _ASM_C6X_THREAD_INFO_H
+
+#ifdef __KERNEL__
+
+#include <asm/page.h>
+
+#ifdef CONFIG_4KSTACKS
+#define THREAD_SIZE 4096
+#define THREAD_SHIFT 12
+#define THREAD_ORDER 0
+#else
+#define THREAD_SIZE 8192
+#define THREAD_SHIFT 13
+#define THREAD_ORDER 1
+#endif
+
+#define THREAD_START_SP (THREAD_SIZE - 8)
+
+#ifndef __ASSEMBLY__
+
+typedef struct {
+ unsigned long seg;
+} mm_segment_t;
+
+/*
+ * low level task data.
+ */
+struct thread_info {
+ struct task_struct *task; /* main task structure */
+ struct exec_domain *exec_domain; /* execution domain */
+ unsigned long flags; /* low level flags */
+ int cpu; /* cpu we're on */
+ int preempt_count; /* 0 = preemptable, <0 = BUG */
+ mm_segment_t addr_limit; /* thread address space */
+ struct restart_block restart_block;
+};
+
+/*
+ * macros/functions for gaining access to the thread information structure
+ *
+ * preempt_count needs to be 1 initially, until the scheduler is functional.
+ */
+#define INIT_THREAD_INFO(tsk) \
+{ \
+ .task = &tsk, \
+ .exec_domain = &default_exec_domain, \
+ .flags = 0, \
+ .cpu = 0, \
+ .preempt_count = INIT_PREEMPT_COUNT, \
+ .addr_limit = KERNEL_DS, \
+ .restart_block = { \
+ .fn = do_no_restart_syscall, \
+ }, \
+}
+
+#define init_thread_info (init_thread_union.thread_info)
+#define init_stack (init_thread_union.stack)
+
+/* get the thread information struct of current task */
+static inline __attribute__((const))
+struct thread_info *current_thread_info(void)
+{
+ struct thread_info *ti;
+ asm volatile (" clr .s2 B15,0,%1,%0\n"
+ : "=b" (ti)
+ : "Iu5" (THREAD_SHIFT - 1));
+ return ti;
+}
+
+#define __HAVE_ARCH_THREAD_INFO_ALLOCATOR
+
+/* thread information allocation */
+#ifdef CONFIG_DEBUG_STACK_USAGE
+#define THREAD_FLAGS (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO)
+#else
+#define THREAD_FLAGS (GFP_KERNEL | __GFP_NOTRACK)
+#endif
+
+#define alloc_thread_info_node(tsk, node) \
+ ((struct thread_info *)__get_free_pages(THREAD_FLAGS, THREAD_ORDER))
+
+#define free_thread_info(ti) free_pages((unsigned long) (ti), THREAD_ORDER)
+#define get_thread_info(ti) get_task_struct((ti)->task)
+#define put_thread_info(ti) put_task_struct((ti)->task)
+#endif /* __ASSEMBLY__ */
+
+#define PREEMPT_ACTIVE 0x10000000
+
+/*
+ * thread information flag bit numbers
+ * - pending work-to-be-done flags are in LSW
+ * - other flags in MSW
+ */
+#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
+#define TIF_NOTIFY_RESUME 1 /* resumption notification requested */
+#define TIF_SIGPENDING 2 /* signal pending */
+#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
+#define TIF_RESTORE_SIGMASK 4 /* restore signal mask in do_signal() */
+
+#define TIF_POLLING_NRFLAG 16 /* true if polling TIF_NEED_RESCHED */
+#define TIF_MEMDIE 17 /* OOM killer killed process */
+
+#define TIF_WORK_MASK 0x00007FFE /* work on irq/exception return */
+#define TIF_ALLWORK_MASK 0x00007FFF /* work on any return to u-space */
+
+#endif /* __KERNEL__ */
+
+#endif /* _ASM_C6X_THREAD_INFO_H */
diff --git a/arch/c6x/kernel/process.c b/arch/c6x/kernel/process.c
new file mode 100644
index 0000000..08ef100
--- /dev/null
+++ b/arch/c6x/kernel/process.c
@@ -0,0 +1,264 @@
+/*
+ * Port on Texas Instruments TMS320C6x architecture
+ *
+ * Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
+ * Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/module.h>
+#include <linux/unistd.h>
+#include <linux/ptrace.h>
+#include <linux/init_task.h>
+#include <linux/tick.h>
+#include <linux/mqueue.h>
+
+#include <asm/machdep.h>
+
+extern asmlinkage void ret_from_fork(void);
+
+static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
+static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
+
+/*
+ * Initial thread structure.
+ */
+union thread_union init_thread_union __init_task_data = {
+ INIT_THREAD_INFO(init_task)
+};
+
+/*
+ * Initial task structure.
+ */
+struct task_struct init_task = INIT_TASK(init_task);
+EXPORT_SYMBOL(init_task);
+
+/*
+ * power off function, if any
+ */
+void (*pm_power_off)(void);
+EXPORT_SYMBOL(pm_power_off);
+
+/*
+ * power management idle function, if any..
+ */
+void (*pm_idle)(void);
+EXPORT_SYMBOL(pm_idle);
+
+static void default_idle(void)
+{
+ asm volatile ("IDLE\n");
+}
+
+/*
+ * The idle loop for C64x
+ */
+void cpu_idle(void)
+{
+ /* endless idle loop with no priority at all */
+ while (1) {
+ tick_nohz_stop_sched_tick(1);
+ while (!need_resched()) {
+ void (*idle)(void);
+
+ smp_rmb();
+ idle = pm_idle;
+ if (!idle)
+ idle = default_idle;
+ idle();
+ }
+ tick_nohz_restart_sched_tick();
+
+ preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
+ }
+}
+
+static void halt_loop(void)
+{
+ printk(KERN_EMERG "System Halted, OK to turn off power\n");
+ local_irq_disable();
+ while (1)
+ ;
+}
+
+void machine_restart(char *__unused)
+{
+ if (c6x_md.restart)
+ c6x_md.restart();
+ halt_loop();
+}
+
+void machine_halt(void)
+{
+ if (c6x_md.halt)
+ c6x_md.halt();
+ halt_loop();
+}
+
+void machine_power_off(void)
+{
+ if (c6x_md.power_off)
+ c6x_md.power_off();
+ halt_loop();
+}
+
+static void kernel_thread_helper(int dummy, void *arg, int (*fn)(void *))
+{
+ do_exit(fn(arg));
+}
+
+/*
+ * Create a kernel thread
+ */
+int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+{
+ struct pt_regs regs;
+
+ /*
+ * copy_thread sets a4 to zero (child return from fork)
+ * so we can't just set things up to directly return to
+ * fn.
+ */
+ memset(&regs, 0, sizeof(regs));
+ regs.b4 = (unsigned long) arg;
+ regs.a6 = (unsigned long) fn;
+ regs.pc = (unsigned long) kernel_thread_helper;
+ local_save_flags(regs.csr);
+ regs.csr |= 1;
+ regs.tsr = 5; /* Set GEE and GIE in TSR */
+
+ /* Ok, create the new process.. */
+ return do_fork(flags | CLONE_VM | CLONE_UNTRACED, -1, &regs,
+ 0, NULL, NULL);
+}
+EXPORT_SYMBOL(kernel_thread);
+
+void flush_thread(void)
+{
+}
+
+void exit_thread(void)
+{
+}
+
+/*
+ * vfork syscall is deprecated but uClibc tests for _NR_vfork as a check
+ * for __libc_vfork() existence. So we provide the syscall even though
+ * __libc_vfork() actually uses the clone syscall.
+ */
+asmlinkage int c6x_vfork(struct pt_regs *regs)
+{
+ return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs,
+ 0, NULL, NULL);
+}
+
+asmlinkage int c6x_clone(struct pt_regs *regs)
+{
+ unsigned long clone_flags;
+ unsigned long newsp;
+
+ /* syscall puts clone_flags in A4 and usp in B4 */
+ clone_flags = regs->orig_a4;
+ if (regs->b4)
+ newsp = regs->b4;
+ else
+ newsp = regs->sp;
+
+ return do_fork(clone_flags, newsp, regs, 0, (int __user *)regs->a6,
+ (int __user *)regs->b6);
+}
+
+/*
+ * Do necessary setup to start up a newly executed thread.
+ */
+void start_thread(struct pt_regs *regs, unsigned int pc, unsigned long usp)
+{
+ /*
+ * The binfmt loader will setup a "full" stack, but the C6X
+ * operates an "empty" stack. So we adjust the usp so that
+ * argc doesn't get destroyed if an interrupt is taken before
+ * it is read from the stack.
+ *
+ * NB: Library startup code needs to match this.
+ */
+ usp -= 8;
+
+ set_fs(USER_DS);
+ regs->pc = pc;
+ regs->sp = usp;
+ regs->tsr |= 0x40; /* set user mode */
+ current->thread.usp = usp;
+}
+
+/*
+ * Copy a new thread context in its stack.
+ */
+int copy_thread(unsigned long clone_flags, unsigned long usp,
+ unsigned long ustk_size,
+ struct task_struct *p, struct pt_regs *regs)
+{
+ struct pt_regs *childregs;
+
+ childregs = task_pt_regs(p);
+
+ *childregs = *regs;
+ childregs->a4 = 0;
+
+ if (usp == -1)
+ /* case of __kernel_thread: we return to supervisor space */
+ childregs->sp = (unsigned long)(childregs + 1);
+ else
+ /* Otherwise use the given stack */
+ childregs->sp = usp;
+
+ /* Set usp/ksp */
+ p->thread.usp = childregs->sp;
+ /* switch_to uses stack to save/restore 14 callee-saved regs */
+ thread_saved_ksp(p) = (unsigned long)childregs - 8;
+ p->thread.pc = (unsigned int) ret_from_fork;
+ p->thread.wchan = (unsigned long) ret_from_fork;
+#ifdef __DSBT__
+ {
+ unsigned long dp;
+
+ asm volatile ("mv .S2 b14,%0\n" : "=b"(dp));
+
+ thread_saved_dp(p) = dp;
+ if (usp == -1)
+ childregs->dp = dp;
+ }
+#endif
+ return 0;
+}
+
+/*
+ * c6x_execve() executes a new program.
+ */
+asmlinkage long c6x_execve(const char __user *name,
+ const char __user *const __user *argv,
+ const char __user *const __user *envp,
+ struct pt_regs *regs)
+{
+ int error;
+ char *filename;
+
+ filename = getname(name);
+ error = PTR_ERR(filename);
+ if (IS_ERR(filename))
+ goto out;
+
+ error = do_execve(filename, argv, envp, regs);
+ putname(filename);
+out:
+ return error;
+}
+
+unsigned long get_wchan(struct task_struct *p)
+{
+ return p->thread.wchan;
+}
diff --git a/arch/c6x/kernel/switch_to.S b/arch/c6x/kernel/switch_to.S
new file mode 100644
index 0000000..09177ed
--- /dev/null
+++ b/arch/c6x/kernel/switch_to.S
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2011 Texas Instruments Incorporated
+ * Author: Mark Salter (msalter@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+
+#define SP B15
+
+ /*
+ * void __switch_to(struct thread_info *prev,
+ * struct thread_info *next,
+ * struct task_struct *tsk) ;
+ */
+ENTRY(__switch_to)
+ LDDW .D2T2 *+B4(THREAD_B15_14),B7:B6
+ || MV .L2X A4,B5 ; prev
+ || MV .L1X B4,A5 ; next
+ || MVC .S2 RILC,B1
+
+ STW .D2T2 B3,*+B5(THREAD_PC)
+ || STDW .D1T1 A13:A12,*+A4(THREAD_A13_12)
+ || MVC .S2 ILC,B0
+
+ LDW .D2T2 *+B4(THREAD_PC),B3
+ || LDDW .D1T1 *+A5(THREAD_A13_12),A13:A12
+
+ STDW .D1T1 A11:A10,*+A4(THREAD_A11_10)
+ || STDW .D2T2 B1:B0,*+B5(THREAD_RICL_ICL)
+#ifndef __DSBT__
+ || MVKL .S2 current_ksp,B1
+#endif
+
+ STDW .D2T2 B15:B14,*+B5(THREAD_B15_14)
+ || STDW .D1T1 A15:A14,*+A4(THREAD_A15_14)
+#ifndef __DSBT__
+ || MVKH .S2 current_ksp,B1
+#endif
+
+ ;; Switch to next SP
+ MV .S2 B7,SP
+#ifdef __DSBT__
+ || STW .D2T2 B7,*+B14(current_ksp)
+#else
+ || STW .D2T2 B7,*B1
+ || MV .L2 B6,B14
+#endif
+ || LDDW .D1T1 *+A5(THREAD_RICL_ICL),A1:A0
+
+ STDW .D2T2 B11:B10,*+B5(THREAD_B11_10)
+ || LDDW .D1T1 *+A5(THREAD_A15_14),A15:A14
+
+ STDW .D2T2 B13:B12,*+B5(THREAD_B13_12)
+ || LDDW .D1T1 *+A5(THREAD_A11_10),A11:A10
+
+ B .S2 B3 ; return in next E1
+ || LDDW .D2T2 *+B4(THREAD_B13_12),B13:B12
+
+ LDDW .D2T2 *+B4(THREAD_B11_10),B11:B10
+ NOP
+
+ MV .L2X A0,B0
+ || MV .S1 A6,A4
+
+ MVC .S2 B0,ILC
+ || MV .L2X A1,B1
+
+ MVC .S2 B1,RILC
+ENDPROC(__switch_to)
--
1.7.6