xen/x86: Use const char * for string literals

For pre-ANSI-C compatibility reasons, string literals have a mutable type, but
it is undefined behaviour to mutate them.

Swap char *'s to const char *'s for variables which hold string literals.

This fixes several violations of MISRA Rule 7.4:

  A string literal shall not be assigned to an object unless the object's type
  is "pointer to const-qualified char".

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/acpi/cpu_idle.c

@@ -302,7 +302,7 @@ static void print_hw_residencies(uint32_t cpu)
            hw_res.cc6, hw_res.cc7);
 }
 
-static char* acpi_cstate_method_name[] =
+static const char *const acpi_cstate_method_name[] =
 {
     "NONE",
     "SYSIO",

xen/arch/x86/cpu/mcheck/mce.c

@@ -1705,7 +1705,7 @@ static void mc_panic_dump(void)
     dprintk(XENLOG_ERR, "End dump mc_info, %x mcinfo dumped\n", mcinfo_dumpped);
 }
 
-void mc_panic(char *s)
+void mc_panic(const char *s)
 {
     is_mc_panic = true;
     console_force_unlock();

xen/arch/x86/cpu/mcheck/mce.h

@@ -57,7 +57,7 @@ struct mcinfo_extended *intel_get_extended_msrs(
 bool mce_available(const struct cpuinfo_x86 *c);
 unsigned int mce_firstbank(struct cpuinfo_x86 *c);
 /* Helper functions used for collecting error telemetry */
-void noreturn mc_panic(char *s);
+void noreturn mc_panic(const char *s);
 void x86_mc_get_cpu_info(unsigned, uint32_t *, uint16_t *, uint16_t *,
                          uint32_t *, uint32_t *, uint32_t *, uint32_t *);
 

xen/arch/x86/e820.c

@@ -363,7 +363,7 @@ static unsigned long __init find_max_pfn(void)
     return max_pfn;
 }
 
-static void __init clip_to_limit(uint64_t limit, char *warnmsg)
+static void __init clip_to_limit(uint64_t limit, const char *warnmsg)
 {
     unsigned int i;
     char _warnmsg[160];

xen/arch/x86/hvm/vmx/vmcs.c

@@ -1949,7 +1949,7 @@ static inline unsigned long vmr(unsigned long field)
     (uint32_t)vmr(fld);                       \
 })
 
-static void vmx_dump_sel(char *name, uint32_t selector)
+static void vmx_dump_sel(const char *name, uint32_t selector)
 {
     uint32_t sel, attr, limit;
     uint64_t base;
@@ -1960,7 +1960,7 @@ static void vmx_dump_sel(char *name, uint32_t selector)
     printk("%s: %04x %05x %08x %016"PRIx64"\n", name, sel, attr, limit, base);
 }
 
-static void vmx_dump_sel2(char *name, uint32_t lim)
+static void vmx_dump_sel2(const char *name, uint32_t lim)
 {
     uint32_t limit;
     uint64_t base;

xen/arch/x86/include/asm/hvm/hvm.h

@@ -92,7 +92,7 @@ struct hvm_vcpu_nonreg_state {
  * supports Intel's VT-x and AMD's SVM extensions.
  */
 struct hvm_function_table {
-    char *name;
+    const char *name;
 
     /* Support Hardware-Assisted Paging? */
     bool_t hap_supported;

xen/arch/x86/oprofile/nmi_int.c

@@ -36,7 +36,7 @@ struct op_x86_model_spec const *__read_mostly model;
 static struct op_msrs cpu_msrs[NR_CPUS];
 static unsigned long saved_lvtpc[NR_CPUS];
 
-static char *cpu_type;
+static const char *cpu_type;
 
 static DEFINE_PER_CPU(struct vcpu *, nmi_cont_vcpu);
 
@@ -309,7 +309,7 @@ void nmi_stop(void)
 }
 
 
-static int __init p4_init(char ** cpu_type)
+static int __init p4_init(const char **cpu_type)
 {
 	unsigned int cpu_model = current_cpu_data.x86_model;
 
@@ -353,7 +353,7 @@ static int __init cf_check force_cpu_type(const char *str)
 }
 custom_param("cpu_type", force_cpu_type);
 
-static int __init ppro_init(char ** cpu_type)
+static int __init ppro_init(const char **cpu_type)
 {
 	if (force_arch_perfmon && cpu_has_arch_perfmon)
 		return 0;
@@ -375,7 +375,7 @@ static int __init ppro_init(char ** cpu_type)
 	return 1;
 }
 
-static int __init arch_perfmon_init(char **cpu_type)
+static int __init arch_perfmon_init(const char **cpu_type)
 {
 	if (!cpu_has_arch_perfmon)
 		return 0;

xen/arch/x86/time.c

@@ -64,8 +64,8 @@ struct cpu_time {
 };
 
 struct platform_timesource {
-    char *id;
-    char *name;
+    const char *id;
+    const char *name;
     u64 frequency;
     /* Post-init this hook may only be invoked via the read_counter() wrapper! */
     u64 (*read_counter)(void);

xen/include/xen/dmi.h

@@ -20,12 +20,12 @@ enum dmi_field {
  */
 struct dmi_strmatch {
 	u8 slot;
-	char *substr;
+	const char *substr;
 };
 
 struct dmi_system_id {
 	int (*callback)(const struct dmi_system_id *);
-	char *ident;
+	const char *ident;
 	struct dmi_strmatch matches[4];
 	void *driver_data;
 };