[Xen-devel] [PATCH v10 3/6] xen/arm: use DEFINE_SYMBOL as required

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Use DEFINE_SYMBOL and the two static inline functions that come with it
for comparisons and subtractions of:

__init_begin, __init_end, __alt_instructions, __alt_instructions_end,
__per_cpu_start, __per_cpu_data_end, _splatform, _eplatform, _sdevice,
_edevice, _asdevice, _aedevice.

Use explicit casts to uintptr_t when it is not possible to use the
provided static inline functions.

M3CM: Rule-18.2: Subtraction between pointers shall only be applied to
pointers that address elements of the same array

https://wiki.sei.cmu.edu/confluence/display/c/ARR36-C.+Do+not+subtract+or+compare+two+pointers+that+do+not+refer+to+the+same+array

QAVerify: 2761
Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
CC: JBeulich@xxxxxxxx
CC: andrew.cooper3@xxxxxxxxxx
---
Changes in v10:
- use DEFINE_SYMBOL
- move changes for _start, _end, _stext, _etext, _srodata, _erodata,
  _sinittext, _einittext to a different patch

Changes in v9:
- use SYMBOLS_SUBTRACT and SYMBOLS_COMPARE
---
 xen/arch/arm/alternative.c   | 10 +++++++---
 xen/arch/arm/device.c        | 13 ++++++++-----
 xen/arch/arm/mm.c            |  7 ++++---
 xen/arch/arm/percpu.c        |  9 +++++----
 xen/arch/arm/platform.c      |  9 ++++++---
 xen/include/asm-arm/percpu.h |  2 +-
 6 files changed, 31 insertions(+), 19 deletions(-)

diff --git a/xen/arch/arm/alternative.c b/xen/arch/arm/alternative.c
index 52ed7ed..cef9cca 100644
--- a/xen/arch/arm/alternative.c
+++ b/xen/arch/arm/alternative.c
@@ -38,7 +38,8 @@
 #undef virt_to_mfn
 #define virt_to_mfn(va) _mfn(__virt_to_mfn(va))
 
-extern const struct alt_instr __alt_instructions[], __alt_instructions_end[];
+DEFINE_SYMBOL(struct alt_instr, alt_instr, __alt_instructions,
+              __alt_instructions_end);
 
 struct alt_region {
     const struct alt_instr *begin;
@@ -131,7 +132,10 @@ static int __apply_alternatives(const struct alt_region 
*region,
     printk(XENLOG_INFO "alternatives: Patching with alt table %p -> %p\n",
            region->begin, region->end);
 
-    for ( alt = region->begin; alt < region->end; alt++ )
+    /* region->begin and region->end might point to different objects. */
+    for ( alt = region->begin;
+          (uintptr_t)alt < (uintptr_t)region->end;
+          alt++ )
     {
         int nr_inst;
 
@@ -204,7 +208,7 @@ static int __apply_alternatives_multi_stop(void *unused)
         BUG_ON(!xenmap);
 
         region.begin = __alt_instructions;
-        region.end = __alt_instructions_end;
+        region.end = (struct alt_instr *)__alt_instructions_end;
 
         ret = __apply_alternatives(&region, xenmap - (void *)_start);
         /* The patching is not expected to fail during boot. */
diff --git a/xen/arch/arm/device.c b/xen/arch/arm/device.c
index 70cd6c1..1ecb9b7 100644
--- a/xen/arch/arm/device.c
+++ b/xen/arch/arm/device.c
@@ -22,8 +22,9 @@
 #include <xen/init.h>
 #include <xen/lib.h>
 
-extern const struct device_desc _sdevice[], _edevice[];
-extern const struct acpi_device_desc _asdevice[], _aedevice[];
+DEFINE_SYMBOL(struct device_desc, device_desc, _sdevice, _edevice);
+DEFINE_SYMBOL(struct acpi_device_desc, acpi_device_desc, _asdevice,
+              _aedevice);
 
 int __init device_init(struct dt_device_node *dev, enum device_class class,
                        const void *data)
@@ -35,7 +36,7 @@ int __init device_init(struct dt_device_node *dev, enum 
device_class class,
     if ( !dt_device_is_available(dev) || dt_device_for_passthrough(dev) )
         return  -ENODEV;
 
-    for ( desc = _sdevice; desc != _edevice; desc++ )
+    for ( desc = _sdevice; device_desc_diff(desc, _edevice) != 0; desc++ )
     {
         if ( desc->class != class )
             continue;
@@ -56,7 +57,9 @@ int __init acpi_device_init(enum device_class class, const 
void *data, int class
 {
     const struct acpi_device_desc *desc;
 
-    for ( desc = _asdevice; desc != _aedevice; desc++ )
+    for ( desc = _asdevice;
+          acpi_device_desc_diff(desc, _aedevice) != 0;
+          desc++ )
     {
         if ( ( desc->class != class ) || ( desc->class_type != class_type ) )
             continue;
@@ -75,7 +78,7 @@ enum device_class device_get_class(const struct 
dt_device_node *dev)
 
     ASSERT(dev != NULL);
 
-    for ( desc = _sdevice; desc != _edevice; desc++ )
+    for ( desc = _sdevice; device_desc_diff(desc, _edevice) != 0; desc++ )
     {
         if ( dt_match_node(desc->dt_match, dev) )
             return desc->class;
diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 01ae2cc..9f31e81 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -157,7 +157,7 @@ unsigned long frametable_virt_end __read_mostly;
 unsigned long max_page;
 unsigned long total_pages;
 
-extern char __init_begin[], __init_end[];
+DEFINE_SYMBOL(char, init, __init_begin, __init_end);
 
 /* Checking VA memory layout alignment. */
 static inline void check_memory_layout_alignment_constraints(void) {
@@ -1122,7 +1122,7 @@ static void set_pte_flags_on_range(const char *p, 
unsigned long l, enum mg mg)
 void free_init_memory(void)
 {
     paddr_t pa = virt_to_maddr(__init_begin);
-    unsigned long len = __init_end - __init_begin;
+    unsigned long len = init_diff(__init_begin, __init_end);
     uint32_t insn;
     unsigned int i, nr = len / sizeof(insn);
     uint32_t *p;
@@ -1140,7 +1140,8 @@ void free_init_memory(void)
 
     set_pte_flags_on_range(__init_begin, len, mg_clear);
     init_domheap_pages(pa, pa + len);
-    printk("Freed %ldkB init memory.\n", (long)(__init_end-__init_begin)>>10);
+    printk("Freed %ldkB init memory.\n",
+           init_diff(__init_begin, __init_end) >> 10);
 }
 
 void arch_dump_shared_mem_info(void)
diff --git a/xen/arch/arm/percpu.c b/xen/arch/arm/percpu.c
index 25442c4..502739d 100644
--- a/xen/arch/arm/percpu.c
+++ b/xen/arch/arm/percpu.c
@@ -6,7 +6,8 @@
 
 unsigned long __per_cpu_offset[NR_CPUS];
 #define INVALID_PERCPU_AREA (-(long)__per_cpu_start)
-#define PERCPU_ORDER (get_order_from_bytes(__per_cpu_data_end-__per_cpu_start))
+#define PERCPU_ORDER (get_order_from_bytes(per_cpu_diff(__per_cpu_start,      \
+                                                        __per_cpu_data_end)))
 
 void __init percpu_init_areas(void)
 {
@@ -22,8 +23,8 @@ static int init_percpu_area(unsigned int cpu)
         return -EBUSY;
     if ( (p = alloc_xenheap_pages(PERCPU_ORDER, 0)) == NULL )
         return -ENOMEM;
-    memset(p, 0, __per_cpu_data_end - __per_cpu_start);
-    __per_cpu_offset[cpu] = p - __per_cpu_start;
+    memset(p, 0, per_cpu_diff(__per_cpu_start, __per_cpu_data_end));
+    __per_cpu_offset[cpu] = (uintptr_t)p - (uintptr_t)__per_cpu_start;
     return 0;
 }
 
@@ -37,7 +38,7 @@ static void _free_percpu_area(struct rcu_head *head)
 {
     struct free_info *info = container_of(head, struct free_info, rcu);
     unsigned int cpu = info->cpu;
-    char *p = __per_cpu_start + __per_cpu_offset[cpu];
+    char *p = (char *)__per_cpu_start + __per_cpu_offset[cpu];
     free_xenheap_pages(p, PERCPU_ORDER);
     __per_cpu_offset[cpu] = INVALID_PERCPU_AREA;
 }
diff --git a/xen/arch/arm/platform.c b/xen/arch/arm/platform.c
index 8eb0b6e..1da33e7 100644
--- a/xen/arch/arm/platform.c
+++ b/xen/arch/arm/platform.c
@@ -22,7 +22,8 @@
 #include <xen/init.h>
 #include <asm/psci.h>
 
-extern const struct platform_desc _splatform[], _eplatform[];
+DEFINE_SYMBOL(struct platform_desc, platform_desc, _splatform,
+              _eplatform);
 
 /* Pointer to the current platform description */
 static const struct platform_desc *platform;
@@ -51,14 +52,16 @@ void __init platform_init(void)
     ASSERT(platform == NULL);
 
     /* Looking for the platform description */
-    for ( platform = _splatform; platform != _eplatform; platform++ )
+    for ( platform = _splatform;
+          platform_desc_diff(platform, _eplatform) != 0;
+          platform++ )
     {
         if ( platform_is_compatible(platform) )
             break;
     }
 
     /* We don't have specific operations for this platform */
-    if ( platform == _eplatform )
+    if ( platform_desc_diff(platform, _eplatform) == 0 )
     {
         /* TODO: dump DT machine compatible node */
         printk(XENLOG_INFO "Platform: Generic System\n");
diff --git a/xen/include/asm-arm/percpu.h b/xen/include/asm-arm/percpu.h
index 6263e77..a589c1c 100644
--- a/xen/include/asm-arm/percpu.h
+++ b/xen/include/asm-arm/percpu.h
@@ -6,7 +6,7 @@
 #include <xen/types.h>
 #include <asm/sysregs.h>
 
-extern char __per_cpu_start[], __per_cpu_data_end[];
+DEFINE_SYMBOL(char, per_cpu, __per_cpu_start, __per_cpu_data_end);
 extern unsigned long __per_cpu_offset[NR_CPUS];
 void percpu_init_areas(void);
 
-- 
1.9.1


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