[PATCH] ppc32: arch code preempt fixes

I figured the best way to stop beeing bothered by users trying to run
preempt was to fix it ;)

Here's a first batch that close some races we had when testing regs->msr
for altivec or FPU enable, then doing the giveup_* function.  A preempt
in between those would have caused us to save a stale altivec or FPU
context.

diff --git a/arch/ppc/kernel/process.c b/arch/ppc/kernel/process.c
index 3eb61658b8d93166df40a63abdd4a5ea6c295638..e94ead3eac9b76061f0f1a62b87e093784afccc3 100644 (file)
--- a/arch/ppc/kernel/process.c
+++ b/arch/ppc/kernel/process.c
@@ -163,6 +163,7 @@ dump_altivec(struct pt_regs *regs, elf_vrregset_t *vrregs)
 void
 enable_kernel_altivec(void)
 {
+       preempt_disable();
 #ifdef CONFIG_SMP
        if (current->thread.regs && (current->thread.regs->msr & MSR_VEC))
                giveup_altivec(current);
@@ -171,12 +172,14 @@ enable_kernel_altivec(void)
 #else
        giveup_altivec(last_task_used_altivec);
 #endif /* __SMP __ */
+       preempt_enable();
 }
 #endif /* CONFIG_ALTIVEC */
 
 void
 enable_kernel_fp(void)
 {
+       preempt_disable();
 #ifdef CONFIG_SMP
        if (current->thread.regs && (current->thread.regs->msr & MSR_FP))
                giveup_fpu(current);
@@ -185,13 +188,16 @@ enable_kernel_fp(void)
 #else
        giveup_fpu(last_task_used_math);
 #endif /* CONFIG_SMP */
+       preempt_enable();
 }
 
 int
 dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpregs)
 {
-       if (tsk->thread.regs && tsk->thread.regs->msr & MSR_FP)
+       preempt_disable();
+       if (tsk->thread.regs && (tsk->thread.regs->msr & MSR_FP))
                giveup_fpu(tsk);
+       preempt_enable();
        memcpy(fpregs, &tsk->thread.fpr[0], sizeof(*fpregs));
        return 1;
 }
@@ -329,12 +335,14 @@ void prepare_to_copy(struct task_struct *tsk)
 
        if (regs == NULL)
                return;
+       preempt_disable();
        if (regs->msr & MSR_FP)
                giveup_fpu(current);
 #ifdef CONFIG_ALTIVEC
        if (regs->msr & MSR_VEC)
                giveup_altivec(current);
 #endif /* CONFIG_ALTIVEC */
+       preempt_enable();
 }
 
 /*
@@ -479,12 +487,14 @@ int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
        error = PTR_ERR(filename);
        if (IS_ERR(filename))
                goto out;
+       preempt_disable();
        if (regs->msr & MSR_FP)
                giveup_fpu(current);
 #ifdef CONFIG_ALTIVEC
        if (regs->msr & MSR_VEC)
                giveup_altivec(current);
 #endif /* CONFIG_ALTIVEC */
+       preempt_enable();
        error = do_execve(filename, (char __user *__user *) a1,
                          (char __user *__user *) a2, regs);
        if (error == 0)

diff --git a/arch/ppc/kernel/traps.c b/arch/ppc/kernel/traps.c
index e5a2c336e3113e5f0abf6c3768924291f97907c4..197b8629b9ae7bd22c2d8192de82a8e8e6ae752f 100644 (file)
--- a/arch/ppc/kernel/traps.c
+++ b/arch/ppc/kernel/traps.c
@@ -391,14 +391,25 @@ check_bug_trap(struct pt_regs *regs)
                return 0;
        if (bug->line & BUG_WARNING_TRAP) {
                /* this is a WARN_ON rather than BUG/BUG_ON */
+#ifdef CONFIG_XMON
+               xmon_printf(KERN_ERR "Badness in %s at %s:%d\n",
+                      bug->function, bug->file,
+                      bug->line & ~BUG_WARNING_TRAP);
+#endif /* CONFIG_XMON */               
                printk(KERN_ERR "Badness in %s at %s:%d\n",
                       bug->function, bug->file,
                       bug->line & ~BUG_WARNING_TRAP);
                dump_stack();
                return 1;
        }
+#ifdef CONFIG_XMON
+       xmon_printf(KERN_CRIT "kernel BUG in %s at %s:%d!\n",
+              bug->function, bug->file, bug->line);
+       xmon(regs);
+#endif /* CONFIG_XMON */
        printk(KERN_CRIT "kernel BUG in %s at %s:%d!\n",
               bug->function, bug->file, bug->line);
+
        return 0;
 }
 
@@ -427,8 +438,14 @@ ProgramCheckException(struct pt_regs *regs)
                int code = 0;
                u32 fpscr;
 
+               /* We must make sure the FP state is consistent with
+                * our MSR_FP in regs
+                */
+               preempt_disable();
                if (regs->msr & MSR_FP)
                        giveup_fpu(current);
+               preempt_enable();
+
                fpscr = current->thread.fpscr;
                fpscr &= fpscr << 22;   /* mask summary bits with enables */
                if (fpscr & FPSCR_VX)
@@ -592,13 +609,17 @@ TAUException(struct pt_regs *regs)
 void
 AltivecAssistException(struct pt_regs *regs)
 {
+       preempt_disable();
        if (regs->msr & MSR_VEC)
                giveup_altivec(current);
+       preempt_enable();
+
        /* XXX quick hack for now: set the non-Java bit in the VSCR */
        current->thread.vscr.u[3] |= 0x10000;
 }
 #endif /* CONFIG_ALTIVEC */
 
+
 void __init trap_init(void)
 {
 }