C6X: process management
Aurelien Jacquiot [Tue, 4 Oct 2011 15:03:44 +0000 (11:03 -0400)]
Original port to early 2.6 kernel using TI COFF toolchain.
Brought up to date by Mark Salter <msalter@redhat.com>

Signed-off-by: Aurelien Jacquiot <a-jacquiot@ti.com>
Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

arch/c6x/include/asm/processor.h [new file with mode: 0644]
arch/c6x/include/asm/thread_info.h [new file with mode: 0644]
arch/c6x/kernel/process.c [new file with mode: 0644]
arch/c6x/kernel/switch_to.S [new file with mode: 0644]

diff --git a/arch/c6x/include/asm/processor.h b/arch/c6x/include/asm/processor.h
new file mode 100644 (file)
index 0000000..8154c4e
--- /dev/null
@@ -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 (file)
index 0000000..fd99148
--- /dev/null
@@ -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 (file)
index 0000000..aa65c87
--- /dev/null
@@ -0,0 +1,263 @@
+/*
+ *  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 <linux/syscalls.h>
+#include <linux/reboot.h>
+
+#include <asm/syscalls.h>
+
+/* hooks for board specific support */
+void   (*c6x_restart)(void);
+void   (*c6x_halt)(void);
+
+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);
+
+static void c6x_idle(void)
+{
+       unsigned long tmp;
+
+       /*
+        * Put local_irq_enable and idle in same execute packet
+        * to make them atomic and avoid race to idle with
+        * interrupts enabled.
+        */
+       asm volatile ("   mvc .s2 CSR,%0\n"
+                     "   or  .d2 1,%0,%0\n"
+                     "   mvc .s2 %0,CSR\n"
+                     "|| idle\n"
+                     : "=b"(tmp));
+}
+
+/*
+ * 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 (1) {
+                       local_irq_disable();
+                       if (need_resched()) {
+                               local_irq_enable();
+                               break;
+                       }
+                       c6x_idle(); /* enables local irqs */
+               }
+               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)
+               asm volatile("idle\n");
+}
+
+void machine_restart(char *__unused)
+{
+       if (c6x_restart)
+               c6x_restart();
+       halt_loop();
+}
+
+void machine_halt(void)
+{
+       if (c6x_halt)
+               c6x_halt();
+       halt_loop();
+}
+
+void machine_power_off(void)
+{
+       if (pm_power_off)
+               pm_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)
+{
+}
+
+SYSCALL_DEFINE1(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.
+ */
+SYSCALL_DEFINE4(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 (file)
index 0000000..09177ed
--- /dev/null
@@ -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)