6 files changed, 91 insertions, 35 deletions

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 080df907f242..e14278d59882 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -17,8 +17,8 @@
 
 #include <asm/glue.h>
 #include <asm/vfpmacros.h>
-#include <asm/hardware.h>               @ should be moved into entry-macro.S
-#include <asm/arch/irqs.h>              @ should be moved into entry-macro.S
+#include <asm/hardware.h>               /* should be moved into entry-macro.S */
+#include <asm/arch/irqs.h>              /* should be moved into entry-macro.S */
 #include <asm/arch/entry-macro.S>
 
 #include "entry-header.S"
@@ -269,7 +269,7 @@ __pabt_svc:
         add     r5, sp, #S_PC
         ldmia   r7, {r2 - r4}                   @ Get USR pc, cpsr
 
-#if __LINUX_ARM_ARCH__ < 6
+#if __LINUX_ARM_ARCH__ < 6 && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
         @ make sure our user space atomic helper is aborted
         cmp     r2, #VIRT_OFFSET
         bichs   r3, r3, #PSR_Z_BIT
@@ -505,9 +505,9 @@ ENTRY(__switch_to)
         mra     r4, r5, acc0
         stmia   ip, {r4, r5}
 #endif
-#ifdef CONFIG_HAS_TLS_REG
+#if defined(CONFIG_HAS_TLS_REG)
         mcr     p15, 0, r3, c13, c0, 3          @ set TLS register
-#else
+#elif !defined(CONFIG_TLS_REG_EMUL)
         mov     r4, #0xffff0fff
         str     r3, [r4, #-15]                  @ TLS val at 0xffff0ff0
 #endif
@@ -616,11 +616,17 @@ __kuser_helper_start:
 
 __kuser_cmpxchg:                                @ 0xffff0fc0
 
-#if __LINUX_ARM_ARCH__ < 6
+#if defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
 
-#ifdef CONFIG_SMP  /* sanity check */
-#error "CONFIG_SMP on a machine supporting pre-ARMv6 processors?"
-#endif
+        /*
+         * Poor you.  No fast solution possible...
+         * The kernel itself must perform the operation.
+         * A special ghost syscall is used for that (see traps.c).
+         */
+        swi     #0x9ffff0
+        mov     pc, lr
+
+#elif __LINUX_ARM_ARCH__ < 6
 
         /*
          * Theory of operation:
@@ -690,11 +696,7 @@ __kuser_cmpxchg:				@ 0xffff0fc0
 
 __kuser_get_tls:                                @ 0xffff0fe0
 
-#ifndef CONFIG_HAS_TLS_REG
-
-#ifdef CONFIG_SMP  /* sanity check */
-#error "CONFIG_SMP without CONFIG_HAS_TLS_REG is wrong"
-#endif
+#if !defined(CONFIG_HAS_TLS_REG) && !defined(CONFIG_TLS_REG_EMUL)
 
         ldr     r0, [pc, #(16 - 8)]             @ TLS stored at 0xffff0ff0
         mov     pc, lr
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 171b3e811c71..4733877296d4 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -19,6 +19,7 @@
 #include <asm/procinfo.h>
 #include <asm/ptrace.h>
 #include <asm/constants.h>
+#include <asm/thread_info.h>
 #include <asm/system.h>
 
 #define PROCINFO_MMUFLAGS       8
@@ -131,7 +132,7 @@ __switch_data:
         .long   processor_id                    @ r4
         .long   __machine_arch_type             @ r5
         .long   cr_alignment                    @ r6
-        .long   init_thread_union+8192          @ sp
+        .long   init_thread_union + THREAD_START_SP @ sp
 
 /*
  * The following fragment of code is executed with the MMU on, and uses
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 26eacd3e5def..8f146a4b4752 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -256,8 +256,6 @@ static unsigned long *thread_info_head;
 static unsigned int nr_thread_info;
 
 #define EXTRA_TASK_STRUCT       4
-#define ll_alloc_task_struct() ((struct thread_info *) __get_free_pages(GFP_KERNEL,1))
-#define ll_free_task_struct(p) free_pages((unsigned long)(p),1)
 
 struct thread_info *alloc_thread_info(struct task_struct *task)
 {
@@ -274,17 +272,16 @@ struct thread_info *alloc_thread_info(struct task_struct *task)
         }
 
         if (!thread)
-                thread = ll_alloc_task_struct();
+                thread = (struct thread_info *)
+                           __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER);
 
-#ifdef CONFIG_MAGIC_SYSRQ
+#ifdef CONFIG_DEBUG_STACK_USAGE
         /*
          * The stack must be cleared if you want SYSRQ-T to
          * give sensible stack usage information
          */
-        if (thread) {
-                char *p = (char *)thread;
-                memzero(p+KERNEL_STACK_SIZE, KERNEL_STACK_SIZE);
-        }
+        if (thread)
+                memzero(thread, THREAD_SIZE);
 #endif
         return thread;
 }
@@ -297,7 +294,7 @@ void free_thread_info(struct thread_info *thread)
                 thread_info_head = p;
                 nr_thread_info += 1;
         } else
-                ll_free_task_struct(thread);
+                free_pages((unsigned long)thread, THREAD_SIZE_ORDER);
 }
 
 /*
@@ -350,7 +347,7 @@ copy_thread(int nr, unsigned long clone_flags, unsigned long stack_start,
         struct thread_info *thread = p->thread_info;
         struct pt_regs *childregs;
 
-        childregs = ((struct pt_regs *)((unsigned long)thread + THREAD_SIZE - 8)) - 1;
+        childregs = ((struct pt_regs *)((unsigned long)thread + THREAD_START_SP)) - 1;
         *childregs = *regs;
         childregs->ARM_r0 = 0;
         childregs->ARM_sp = stack_start;
@@ -447,15 +444,17 @@ EXPORT_SYMBOL(kernel_thread);
 unsigned long get_wchan(struct task_struct *p)
 {
         unsigned long fp, lr;
-        unsigned long stack_page;
+        unsigned long stack_start, stack_end;
         int count = 0;
         if (!p || p == current || p->state == TASK_RUNNING)
                 return 0;
 
-        stack_page = 4096 + (unsigned long)p->thread_info;
+        stack_start = (unsigned long)(p->thread_info + 1);
+        stack_end = ((unsigned long)p->thread_info) + THREAD_SIZE;
+
         fp = thread_saved_fp(p);
         do {
-                if (fp < stack_page || fp > 4092+stack_page)
+                if (fp < stack_start || fp > stack_end)
                         return 0;
                 lr = pc_pointer (((unsigned long *)fp)[-1]);
                 if (!in_sched_functions(lr))
diff --git a/arch/arm/kernel/sys_arm.c b/arch/arm/kernel/sys_arm.c
index ef32577da304..f897ce2ccf0d 100644
--- a/arch/arm/kernel/sys_arm.c
+++ b/arch/arm/kernel/sys_arm.c
@@ -302,7 +302,7 @@ long execve(const char *filename, char **argv, char **envp)
                 "b      ret_to_user"
                 :
                 : "r" (current_thread_info()),
-                  "Ir" (THREAD_SIZE - 8 - sizeof(regs)),
+                  "Ir" (THREAD_START_SP - sizeof(regs)),
                   "r" (&regs),
                   "Ir" (sizeof(regs))
                 : "r0", "r1", "r2", "r3", "ip", "memory");
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 3a001fe5540b..45d2a032d890 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -218,7 +218,8 @@ NORET_TYPE void die(const char *str, struct pt_regs *regs, int err)
                 tsk->comm, tsk->pid, tsk->thread_info + 1);
 
         if (!user_mode(regs) || in_interrupt()) {
-                dump_mem("Stack: ", regs->ARM_sp, 8192+(unsigned long)tsk->thread_info);
+                dump_mem("Stack: ", regs->ARM_sp,
+                         THREAD_SIZE + (unsigned long)tsk->thread_info);
                 dump_backtrace(regs, tsk);
                 dump_instr(regs);
         }
@@ -450,9 +451,9 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
 
         case NR(set_tls):
                 thread->tp_value = regs->ARM_r0;
-#ifdef CONFIG_HAS_TLS_REG
+#if defined(CONFIG_HAS_TLS_REG)
                 asm ("mcr p15, 0, %0, c13, c0, 3" : : "r" (regs->ARM_r0) );
-#else
+#elif !defined(CONFIG_TLS_REG_EMUL)
                 /*
                  * User space must never try to access this directly.
                  * Expect your app to break eventually if you do so.
@@ -463,6 +464,55 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
 #endif
                 return 0;
 
+#ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
+        /*
+         * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
+         * Return zero in r0 if *MEM was changed or non-zero if no exchange
+         * happened.  Also set the user C flag accordingly.
+         * If access permissions have to be fixed up then non-zero is
+         * returned and the operation has to be re-attempted.
+         *
+         * *NOTE*: This is a ghost syscall private to the kernel.  Only the
+         * __kuser_cmpxchg code in entry-armv.S should be aware of its
+         * existence.  Don't ever use this from user code.
+         */
+        case 0xfff0:
+        {
+                extern void do_DataAbort(unsigned long addr, unsigned int fsr,
+                                         struct pt_regs *regs);
+                unsigned long val;
+                unsigned long addr = regs->ARM_r2;
+                struct mm_struct *mm = current->mm;
+                pgd_t *pgd; pmd_t *pmd; pte_t *pte;
+
+                regs->ARM_cpsr &= ~PSR_C_BIT;
+                spin_lock(&mm->page_table_lock);
+                pgd = pgd_offset(mm, addr);
+                if (!pgd_present(*pgd))
+                        goto bad_access;
+                pmd = pmd_offset(pgd, addr);
+                if (!pmd_present(*pmd))
+                        goto bad_access;
+                pte = pte_offset_map(pmd, addr);
+                if (!pte_present(*pte) || !pte_write(*pte))
+                        goto bad_access;
+                val = *(unsigned long *)addr;
+                val -= regs->ARM_r0;
+                if (val == 0) {
+                        *(unsigned long *)addr = regs->ARM_r1;
+                        regs->ARM_cpsr |= PSR_C_BIT;
+                }
+                spin_unlock(&mm->page_table_lock);
+                return val;
+
+                bad_access:
+                spin_unlock(&mm->page_table_lock);
+                /* simulate a read access fault */
+                do_DataAbort(addr, 15 + (1 << 11), regs);
+                return -1;
+        }
+#endif
+
         default:
                 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
                    if not implemented, rather than raising SIGILL.  This
@@ -497,11 +547,14 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
         return 0;
 }
 
-#if defined(CONFIG_CPU_32v6) && !defined(CONFIG_HAS_TLS_REG)
+#ifdef CONFIG_TLS_REG_EMUL
 
 /*
  * We might be running on an ARMv6+ processor which should have the TLS
- * register, but for some reason we can't use it and have to emulate it.
+ * register but for some reason we can't use it, or maybe an SMP system
+ * using a pre-ARMv6 processor (there are apparently a few prototypes like
+ * that in existence) and therefore access to that register must be
+ * emulated.
  */
 
 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index a39c6a42d68a..ad2d66c93a5c 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -5,6 +5,7 @@
 
 #include <asm-generic/vmlinux.lds.h>
 #include <linux/config.h>
+#include <asm/thread_info.h>
         
 OUTPUT_ARCH(arm)
 ENTRY(stext)
@@ -103,7 +104,7 @@ SECTIONS
         __data_loc = ALIGN(4);          /* location in binary */
         . = DATAADDR;
 #else
-        . = ALIGN(8192);
+        . = ALIGN(THREAD_SIZE);
         __data_loc = .;
 #endif