[PATCH] i386 cpu hotplug: don't access freed memory

i386 CPU init code accesses freed init memory when booting a newly-started
processor after CPU hotplug.  The cpu_devs array is searched to find the
vendor and it contains pointers to freed data.

Fix that by:

        1. Zeroing entries for freed vendor data after bootup.
        2. Changing Transmeta, NSC and UMC to all __init[data].
        3. Printing a warning (once only) and setting this_cpu
           to a safe default when the vendor is not found.

This does not change behavior for AMD systems.  They were broken already
but no error was reported.
Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/i386/kernel/cpu/amd.c

@@ -282,3 +282,11 @@ int __init amd_init_cpu(void)
 }
 
 //early_arch_initcall(amd_init_cpu);
+
+static int __init amd_exit_cpu(void)
+{
+	cpu_devs[X86_VENDOR_AMD] = NULL;
+	return 0;
+}
+
+late_initcall(amd_exit_cpu);

arch/i386/kernel/cpu/centaur.c

@@ -470,3 +470,11 @@ int __init centaur_init_cpu(void)
 }
 
 //early_arch_initcall(centaur_init_cpu);
+
+static int __init centaur_exit_cpu(void)
+{
+	cpu_devs[X86_VENDOR_CENTAUR] = NULL;
+	return 0;
+}
+
+late_initcall(centaur_exit_cpu);

arch/i386/kernel/cpu/common.c

@@ -44,6 +44,7 @@ static void default_init(struct cpuinfo_x86 * c)
 
 static struct cpu_dev default_cpu = {
 	.c_init	= default_init,
+	.c_vendor = "Unknown",
 };
 static struct cpu_dev * this_cpu = &default_cpu;
 
@@ -150,6 +151,7 @@ static void __devinit get_cpu_vendor(struct cpuinfo_x86 *c, int early)
 {
 	char *v = c->x86_vendor_id;
 	int i;
+	static int printed;
 
 	for (i = 0; i < X86_VENDOR_NUM; i++) {
 		if (cpu_devs[i]) {
@@ -159,10 +161,17 @@ static void __devinit get_cpu_vendor(struct cpuinfo_x86 *c, int early)
 				c->x86_vendor = i;
 				if (!early)
 					this_cpu = cpu_devs[i];
-				break;
+				return;
+			}
 		}
 	}
+	if (!printed) {
+		printed++;
+		printk(KERN_ERR "CPU: Vendor unknown, using generic init.\n");
+		printk(KERN_ERR "CPU: Your system may be unstable.\n");
 	}
+	c->x86_vendor = X86_VENDOR_UNKNOWN;
+	this_cpu = &default_cpu;
 }
 
 

arch/i386/kernel/cpu/cyrix.c

@@ -345,7 +345,7 @@ static void __init init_cyrix(struct cpuinfo_x86 *c)
 /*
  * Handle National Semiconductor branded processors
  */
-static void __devinit init_nsc(struct cpuinfo_x86 *c)
+static void __init init_nsc(struct cpuinfo_x86 *c)
 {
 	/* There may be GX1 processors in the wild that are branded
 	 * NSC and not Cyrix.
@@ -444,6 +444,14 @@ int __init cyrix_init_cpu(void)
 
 //early_arch_initcall(cyrix_init_cpu);
 
+static int __init cyrix_exit_cpu(void)
+{
+	cpu_devs[X86_VENDOR_CYRIX] = NULL;
+	return 0;
+}
+
+late_initcall(cyrix_exit_cpu);
+
 static struct cpu_dev nsc_cpu_dev __initdata = {
 	.c_vendor	= "NSC",
 	.c_ident 	= { "Geode by NSC" },
@@ -458,3 +466,11 @@ int __init nsc_init_cpu(void)
 }
 
 //early_arch_initcall(nsc_init_cpu);
+
+static int __init nsc_exit_cpu(void)
+{
+	cpu_devs[X86_VENDOR_NSC] = NULL;
+	return 0;
+}
+
+late_initcall(nsc_exit_cpu);

arch/i386/kernel/cpu/intel_cacheinfo.c

@@ -152,6 +152,7 @@ static int __cpuinit cpuid4_cache_lookup(int index, struct _cpuid4_info *this_le
 	return 0;
 }
 
+/* will only be called once; __init is safe here */
 static int __init find_num_cache_leaves(void)
 {
 	unsigned int		eax, ebx, ecx, edx;

arch/i386/kernel/cpu/nexgen.c

@@ -61,3 +61,11 @@ int __init nexgen_init_cpu(void)
 }
 
 //early_arch_initcall(nexgen_init_cpu);
+
+static int __init nexgen_exit_cpu(void)
+{
+	cpu_devs[X86_VENDOR_NEXGEN] = NULL;
+	return 0;
+}
+
+late_initcall(nexgen_exit_cpu);

arch/i386/kernel/cpu/rise.c

@@ -51,3 +51,11 @@ int __init rise_init_cpu(void)
 }
 
 //early_arch_initcall(rise_init_cpu);
+
+static int __init rise_exit_cpu(void)
+{
+	cpu_devs[X86_VENDOR_RISE] = NULL;
+	return 0;
+}
+
+late_initcall(rise_exit_cpu);

arch/i386/kernel/cpu/transmeta.c

@@ -84,7 +84,7 @@ static void __init init_transmeta(struct cpuinfo_x86 *c)
 #endif
 }
 
-static void transmeta_identify(struct cpuinfo_x86 * c)
+static void __init transmeta_identify(struct cpuinfo_x86 * c)
 {
 	u32 xlvl;
 	generic_identify(c);
@@ -111,3 +111,11 @@ int __init transmeta_init_cpu(void)
 }
 
 //early_arch_initcall(transmeta_init_cpu);
+
+static int __init transmeta_exit_cpu(void)
+{
+	cpu_devs[X86_VENDOR_TRANSMETA] = NULL;
+	return 0;
+}
+
+late_initcall(transmeta_exit_cpu);

arch/i386/kernel/cpu/umc.c

@@ -31,3 +31,11 @@ int __init umc_init_cpu(void)
 }
 
 //early_arch_initcall(umc_init_cpu);
+
+static int __init umc_exit_cpu(void)
+{
+	cpu_devs[X86_VENDOR_UMC] = NULL;
+	return 0;
+}
+
+late_initcall(umc_exit_cpu);