[PATCH 14/30] microblaze_mmu_v1: Update process creation for MMU

monstr
2009-04-27T09:56:31Z

From: Michal Simek <monstr@monstr.eu>

Signed-off-by: Michal Simek <monstr@monstr.eu>
---
arch/microblaze/include/asm/processor.h | 97 +++++++++++++++++++++++++++++-
arch/microblaze/include/asm/registers.h | 21 ++++++-
arch/microblaze/include/asm/segment.h | 10 +++-
arch/microblaze/kernel/process.c | 58 ++++++++++++++++++
4 files changed, 178 insertions(+), 8 deletions(-)

diff --git a/arch/microblaze/include/asm/processor.h b/arch/microblaze/include/asm/processor.h
index 9329029..f206fc1 100644
--- a/arch/microblaze/include/asm/processor.h
+++ b/arch/microblaze/include/asm/processor.h
@@ -1,6 +1,6 @@
/*
- * Copyright (C) 2008 Michal Simek
- * Copyright (C) 2008 PetaLogix
+ * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
+ * Copyright (C) 2008-2009 PetaLogix
* Copyright (C) 2006 Atmark Techno, Inc.
*
* This file is subject to the terms and conditions of the GNU General Public
@@ -26,14 +26,15 @@ extern const struct seq_operations cpuinfo_op;
# define cpu_sleep() do {} while (0)
# define prepare_to_copy(tsk) do {} while (0)

-# endif /* __ASSEMBLY__ */
-
#define task_pt_regs(tsk) \
(((struct pt_regs *)(THREAD_SIZE + task_stack_page(tsk))) - 1)

/* Do necessary setup to start up a newly executed thread. */
void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp);

+# endif /* __ASSEMBLY__ */
+
+# ifndef CONFIG_MMU
/*
* User space process size: memory size
*
@@ -85,4 +86,92 @@ extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
# define KSTK_EIP(tsk) (0)
# define KSTK_ESP(tsk) (0)

+# else /* CONFIG_MMU */
+
+/*
+ * This is used to define STACK_TOP, and with MMU it must be below
+ * kernel base to select the correct PGD when handling MMU exceptions.
+ */
+# define TASK_SIZE (CONFIG_KERNEL_START)
+
+/*
+ * This decides where the kernel will search for a free chunk of vm
+ * space during mmap's.
+ */
+# define TASK_UNMAPPED_BASE (TASK_SIZE / 8 * 3)
+
+# define THREAD_KSP 0
+
+# ifndef __ASSEMBLY__
+
+/*
+ * Default implementation of macro that returns current
+ * instruction pointer ("program counter").
+ */
+# define current_text_addr() ({ __label__ _l; _l: &&_l; })
+
+/* If you change this, you must change the associated assembly-languages
+ * constants defined below, THREAD_*.
+ */
+struct thread_struct {
+ /* kernel stack pointer (must be first field in structure) */
+ unsigned long ksp;
+ unsigned long ksp_limit; /* if ksp <= ksp_limit stack overflow */
+ mm_segment_t fs; /* for get_fs() validation */
+ void *pgdir; /* root of page-table tree */
+ struct pt_regs *regs; /* Pointer to saved register state */
+};
+
+# define INIT_THREAD { \
+ .ksp = sizeof init_stack + (unsigned long)init_stack, \
+ .fs = KERNEL_DS, \
+ .pgdir = swapper_pg_dir, \
+}
+
+/* Do necessary setup to start up a newly executed thread. */
+void start_thread(struct pt_regs *regs,
+ unsigned long pc, unsigned long usp);
+
+/* Free all resources held by a thread. */
+extern inline void release_thread(struct task_struct *dead_task)
+{
+}
+
+extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
+
+/* Free current thread data structures etc. */
+static inline void exit_thread(void)
+{
+}
+
+/* Return saved (kernel) PC of a blocked thread. */
+# define thread_saved_pc(tsk) \
+ ((tsk)->thread.regs ? (tsk)->thread.regs->r15 : 0)
+
+unsigned long get_wchan(struct task_struct *p);
+
+/* The size allocated for kernel stacks. This _must_ be a power of two! */
+# define KERNEL_STACK_SIZE 0x2000
+
+/* Return some info about the user process TASK. */
+# define task_tos(task) ((unsigned long)(task) + KERNEL_STACK_SIZE)
+# define task_regs(task) ((struct pt_regs *)task_tos(task) - 1)
+
+# define task_pt_regs_plus_args(tsk) \
+ (((void *)task_pt_regs(tsk)) - STATE_SAVE_ARG_SPACE)
+
+# define task_sp(task) (task_regs(task)->r1)
+# define task_pc(task) (task_regs(task)->pc)
+/* Grotty old names for some. */
+# define KSTK_EIP(task) (task_pc(task))
+# define KSTK_ESP(task) (task_sp(task))
+
+/* FIXME */
+# define deactivate_mm(tsk, mm) do { } while (0)
+
+# define STACK_TOP TASK_SIZE
+# define STACK_TOP_MAX STACK_TOP
+
+# endif /* __ASSEMBLY__ */
+# endif /* CONFIG_MMU */
#endif /* _ASM_MICROBLAZE_PROCESSOR_H */
diff --git a/arch/microblaze/include/asm/registers.h b/arch/microblaze/include/asm/registers.h
index 834142d..68c3afb 100644
--- a/arch/microblaze/include/asm/registers.h
+++ b/arch/microblaze/include/asm/registers.h
@@ -1,6 +1,6 @@
/*
- * Copyright (C) 2008 Michal Simek
- * Copyright (C) 2008 PetaLogix
+ * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
+ * Copyright (C) 2008-2009 PetaLogix
* Copyright (C) 2006 Atmark Techno, Inc.
*
* This file is subject to the terms and conditions of the GNU General Public
@@ -30,4 +30,21 @@
#define FSR_UF (1<<1) /* Underflow */
#define FSR_DO (1<<0) /* Denormalized operand error */

+# ifdef CONFIG_MMU
+/* Machine State Register (MSR) Fields */
+# define MSR_UM (1<<11) /* User Mode */
+# define MSR_UMS (1<<12) /* User Mode Save */
+# define MSR_VM (1<<13) /* Virtual Mode */
+# define MSR_VMS (1<<14) /* Virtual Mode Save */
+
+# define MSR_KERNEL (MSR_EE | MSR_VM)
+/* # define MSR_USER (MSR_KERNEL | MSR_UM | MSR_IE) */
+# define MSR_KERNEL_VMS (MSR_EE | MSR_VMS)
+/* # define MSR_USER_VMS (MSR_KERNEL_VMS | MSR_UMS | MSR_IE) */
+
+/* Exception State Register (ESR) Fields */
+# define ESR_DIZ (1<<11) /* Zone Protection */
+# define ESR_S (1<<10) /* Store instruction */
+
+# endif /* CONFIG_MMU */
#endif /* _ASM_MICROBLAZE_REGISTERS_H */
diff --git a/arch/microblaze/include/asm/segment.h b/arch/microblaze/include/asm/segment.h
index 7f5dcc5..18d1c4b 100644
--- a/arch/microblaze/include/asm/segment.h
+++ b/arch/microblaze/include/asm/segment.h
@@ -1,6 +1,6 @@
/*
- * Copyright (C) 2008 Michal Simek
- * Copyright (C) 2008 PetaLogix
+ * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
+ * Copyright (C) 2008-2009 PetaLogix
* Copyright (C) 2006 Atmark Techno, Inc.
*
* This file is subject to the terms and conditions of the GNU General Public
@@ -29,8 +29,14 @@ typedef struct {
*
* For non-MMU arch like Microblaze, KERNEL_DS and USER_DS is equal.
*/
+
+# ifndef CONFIG_MMU
# define KERNEL_DS ((mm_segment_t){0})
# define USER_DS KERNEL_DS
+# else
+# define KERNEL_DS ((mm_segment_t){0xFFFFF000})
+# define USER_DS ((mm_segment_t){0xC0000000})
+# endif

# define get_ds() (KERNEL_DS)
# define get_fs() (current_thread_info()->addr_limit)
diff --git a/arch/microblaze/kernel/process.c b/arch/microblaze/kernel/process.c
index 07d4fa3..f289ff3 100644
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -126,9 +126,54 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
else
childregs->r1 = ((unsigned long) ti) + THREAD_SIZE;

+#ifndef CONFIG_MMU
memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
ti->cpu_context.r1 = (unsigned long)childregs;
ti->cpu_context.msr = (unsigned long)childregs->msr;
+#else
+
+ /* if creating a kernel thread then update the current reg (we don't
+ * want to use the parent's value when restoring by POP_STATE) */
+ if (kernel_mode(regs))
+ /* save new current on stack to use POP_STATE */
+ childregs->CURRENT_TASK = (unsigned long)p;
+ /* if returning to user then use the parent's value of this register */
+
+ /* if we're creating a new kernel thread then just zeroing all
+ * the registers. That's OK for a brand new thread.*/
+ /* Pls. note that some of them will be restored in POP_STATE */
+ if (kernel_mode(regs))
+ memset(&ti->cpu_context, 0, sizeof(struct cpu_context));
+ /* if this thread is created for fork/vfork/clone, then we want to
+ * restore all the parent's context */
+ /* in addition to the registers which will be restored by POP_STATE */
+ else {
+ ti->cpu_context = *(struct cpu_context *)regs;
+ childregs->msr |= MSR_UMS;
+ }
+
+ /* FIXME STATE_SAVE_PT_OFFSET; */
+ ti->cpu_context.r1 = (unsigned long)childregs - STATE_SAVE_ARG_SPACE;
+ /* we should consider the fact that childregs is a copy of the parent
+ * regs which were saved immediately after entering the kernel state
+ * before enabling VM. This MSR will be restored in switch_to and
+ * RETURN() and we want to have the right machine state there
+ * specifically this state must have INTs disabled before and enabled
+ * after performing rtbd
+ * compose the right MSR for RETURN(). It will work for switch_to also
+ * excepting for VM and UMS
+ * don't touch UMS , CARRY and cache bits
+ * right now MSR is a copy of parent one */
+ childregs->msr |= MSR_BIP;
+ childregs->msr &= ~MSR_EIP;
+ childregs->msr |= MSR_IE;
+ childregs->msr &= ~MSR_VM;
+ childregs->msr |= MSR_VMS;
+ childregs->msr |= MSR_EE; /* exceptions will be enabled*/
+
+ ti->cpu_context.msr = (childregs->msr|MSR_VM);
+ ti->cpu_context.msr &= ~MSR_UMS; /* switch_to to kernel mode */
+#endif
ti->cpu_context.r15 = (unsigned long)ret_from_fork - 8;

if (clone_flags & CLONE_SETTLS)
@@ -137,6 +182,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
return 0;
}

+#ifndef CONFIG_MMU
/*
* Return saved PC of a blocked thread.
*/
@@ -151,6 +197,7 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
else
return ctx->r14;
}
+#endif

static void kernel_thread_helper(int (*fn)(void *), void *arg)
{
@@ -188,3 +235,14 @@ void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long usp)
regs->r1 = usp;
regs->pt_mode = 0;
}
+
+#ifdef CONFIG_MMU
+#include <linux/elfcore.h>
+/*
+ * Set up a thread for executing a new program
+ */
+int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)
+{
+ return 0; /* MicroBlaze has no separate FPU registers */
+}
+#endif /* CONFIG_MMU */
--
1.5.5.1