diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 41e9ab40cd54..f70bd090dacd 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -822,6 +822,7 @@ static void __init prom_send_capabilities(void)
 		/* try calling the ibm,client-architecture-support method */
 		if (call_prom_ret("call-method", 3, 2, &ret,
 				  ADDR("ibm,client-architecture-support"),
+				  root,
 				  ADDR(ibm_architecture_vec)) == 0) {
 			/* the call exists... */
 			if (ret)
@@ -1622,6 +1623,15 @@ static int __init prom_find_machine_type(void)
 			if (strstr(p, RELOC("Power Macintosh")) ||
 			    strstr(p, RELOC("MacRISC")))
 				return PLATFORM_POWERMAC;
+#ifdef CONFIG_PPC64
+			/* We must make sure we don't detect the IBM Cell
+			 * blades as pSeries due to some firmware issues,
+			 * so we do it here.
+			 */
+			if (strstr(p, RELOC("IBM,CBEA")) ||
+			    strstr(p, RELOC("IBM,CPBW-1.0")))
+				return PLATFORM_GENERIC;
+#endif /* CONFIG_PPC64 */
 			i += sl + 1;
 		}
 	}
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 01e3c08cb550..8fdeca2d4597 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -803,10 +803,13 @@ static int do_setcontext(struct ucontext __user *ucp, struct pt_regs *regs, int
 		if (__get_user(cmcp, &ucp->uc_regs))
 			return -EFAULT;
 		mcp = (struct mcontext __user *)(u64)cmcp;
+		/* no need to check access_ok(mcp), since mcp < 4GB */
 	}
 #else
 	if (__get_user(mcp, &ucp->uc_regs))
 		return -EFAULT;
+	if (!access_ok(VERIFY_READ, mcp, sizeof(*mcp)))
+		return -EFAULT;
 #endif
 	restore_sigmask(&set);
 	if (restore_user_regs(regs, mcp, sig))
@@ -908,13 +911,14 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
 {
 	struct sig_dbg_op op;
 	int i;
+	unsigned char tmp;
 	unsigned long new_msr = regs->msr;
 #if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
 	unsigned long new_dbcr0 = current->thread.dbcr0;
 #endif
 
 	for (i=0; i<ndbg; i++) {
-		if (__copy_from_user(&op, dbg, sizeof(op)))
+		if (copy_from_user(&op, dbg + i, sizeof(op)))
 			return -EFAULT;
 		switch (op.dbg_type) {
 		case SIG_DBG_SINGLE_STEPPING:
@@ -959,6 +963,11 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
 	current->thread.dbcr0 = new_dbcr0;
 #endif
 
+	if (!access_ok(VERIFY_READ, ctx, sizeof(*ctx))
+	    || __get_user(tmp, (u8 __user *) ctx)
+	    || __get_user(tmp, (u8 __user *) (ctx + 1) - 1))
+		return -EFAULT;
+
 	/*
 	 * If we get a fault copying the context into the kernel's
 	 * image of the user's registers, we can't just return -EFAULT
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 27f65b95184d..c2db642f4cdd 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -182,6 +182,8 @@ static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
 	err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
 	if (err)
 		return err;
+	if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128)))
+		return -EFAULT;
 	/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
 	if (v_regs != 0 && (msr & MSR_VEC) != 0)
 		err |= __copy_from_user(current->thread.vr, v_regs,
diff --git a/arch/powerpc/platforms/cell/setup.c b/arch/powerpc/platforms/cell/setup.c
index 6574b22b3cf3..fd3e5609e3e0 100644
--- a/arch/powerpc/platforms/cell/setup.c
+++ b/arch/powerpc/platforms/cell/setup.c
@@ -125,14 +125,13 @@ static void __init cell_init_early(void)
 
 static int __init cell_probe(void)
 {
-	/* XXX This is temporary, the Cell maintainer will come up with
-	 * more appropriate detection logic
-	 */
 	unsigned long root = of_get_flat_dt_root();
-	if (!of_flat_dt_is_compatible(root, "IBM,CPBW-1.0"))
-		return 0;
 
-	return 1;
+	if (of_flat_dt_is_compatible(root, "IBM,CBEA") ||
+	    of_flat_dt_is_compatible(root, "IBM,CPBW-1.0"))
+		return 1;
+
+	return 0;
 }
 
 /*
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 5f79f01c44f2..3ba87835757e 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -389,6 +389,7 @@ static int __init pSeries_probe_hypertas(unsigned long node,
 
 static int __init pSeries_probe(void)
 {
+	unsigned long root = of_get_flat_dt_root();
  	char *dtype = of_get_flat_dt_prop(of_get_flat_dt_root(),
  					  "device_type", NULL);
  	if (dtype == NULL)
@@ -396,6 +397,13 @@ static int __init pSeries_probe(void)
  	if (strcmp(dtype, "chrp"))
 		return 0;
 
+	/* Cell blades firmware claims to be chrp while it's not. Until this
+	 * is fixed, we need to avoid those here.
+	 */
+	if (of_flat_dt_is_compatible(root, "IBM,CPBW-1.0") ||
+	    of_flat_dt_is_compatible(root, "IBM,CBEA"))
+		return 0;
+
 	DBG("pSeries detected, looking for LPAR capability...\n");
 
 	/* Now try to figure out if we are running on LPAR */