[Xen-devel] [PATCH v5 3/4] xen/x86: use SYMBOL when required

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Use SYMBOL in cases of comparisons and subtractions of:

_start, _end, __init_begin, __init_end,  __2M_text_end,
__2M_rodata_start, __2M_rodata_end, __2M_init_start,__2M_init_end,
__2M_rwdata_start, __2M_rwdata_end, _stext, _etext, _srodata, _erodata,
__end_vpci_array, __start_vpci_array, _sinittext, _einittext,
_stextentry, _etextentry, __start_bug_frames, __stop_bug_frames_0,
__stop_bug_frames_1, __stop_bug_frames_2,__stop_bug_frames_3,
__note_gnu_build_id_start, __note_gnu_build_id_end, __start___ex_table,
__stop___ex_table, __start___pre_ex_table, __stop___pre_ex_table,
__lock_profile_start, __lock_profile_end, __param_start,
__param_end, __setup_start, __setup_end, __initcall_start,
__initcall_end, __presmp_initcall_end, __trampoline_rel_start,
__trampoline_rel_stop, __trampoline_seg_start, __trampoline_seg_stop
__alt_instructions, __alt_instructions_end, __ctors_start, __ctors_end,
__end_schedulers_array, __start_schedulers_array, __bss_start,
__bss_end, __per_cpu_start, __per_cpu_data_end, _splatform, _eplatform,
_sdevice, _edevice, _asdevice, _aedevice, __proc_info_start,
__proc_info_end, _sdtb


as by the C standard [1].

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

[1] 
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 v5:
- remove two spurious changes
- split into three patches
- remove SYMBOL() from derived variables
---
 xen/arch/x86/alternative.c  | 2 +-
 xen/arch/x86/efi/efi-boot.h | 4 ++--
 xen/arch/x86/percpu.c       | 8 ++++----
 xen/arch/x86/setup.c        | 8 +++++---
 xen/arch/x86/smpboot.c      | 3 ++-
 xen/drivers/vpci/vpci.c     | 2 +-
 6 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/xen/arch/x86/alternative.c b/xen/arch/x86/alternative.c
index b8c819a..280ee28 100644
--- a/xen/arch/x86/alternative.c
+++ b/xen/arch/x86/alternative.c
@@ -194,7 +194,7 @@ void init_or_livepatch apply_alternatives(struct alt_instr 
*start,
      * So be careful if you want to change the scan order to any other
      * order.
      */
-    for ( a = base = start; a < end; a++ )
+    for ( a = base = start; (unsigned long)a < SYMBOL(end); a++ )
     {
         uint8_t *orig = ALT_ORIG_PTR(a);
         uint8_t *repl = ALT_REPL_PTR(a);
diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index 5789d2c..837f5ba 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -112,11 +112,11 @@ static void __init relocate_trampoline(unsigned long phys)
 
     /* Apply relocations to trampoline. */
     for ( trampoline_ptr = __trampoline_rel_start;
-          trampoline_ptr < __trampoline_rel_stop;
+          (unsigned long)trampoline_ptr < SYMBOL(__trampoline_rel_stop);
           ++trampoline_ptr )
         *(u32 *)(*trampoline_ptr + (long)trampoline_ptr) += phys;
     for ( trampoline_ptr = __trampoline_seg_start;
-          trampoline_ptr < __trampoline_seg_stop;
+          (unsigned long)trampoline_ptr < SYMBOL(__trampoline_seg_stop);
           ++trampoline_ptr )
         *(u16 *)(*trampoline_ptr + (long)trampoline_ptr) = phys >> 4;
 }
diff --git a/xen/arch/x86/percpu.c b/xen/arch/x86/percpu.c
index 8be4ebd..5e87e91 100644
--- a/xen/arch/x86/percpu.c
+++ b/xen/arch/x86/percpu.c
@@ -13,7 +13,7 @@ unsigned long __per_cpu_offset[NR_CPUS];
  * context of PV guests.
  */
 #define INVALID_PERCPU_AREA (0x8000000000000000L - (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(SYMBOL(__per_cpu_data_end) - 
SYMBOL(__per_cpu_start))
 
 void __init percpu_init_areas(void)
 {
@@ -33,8 +33,8 @@ static int init_percpu_area(unsigned int cpu)
     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, SYMBOL(__per_cpu_data_end) - SYMBOL(__per_cpu_start));
+    __per_cpu_offset[cpu] = (unsigned long)p - SYMBOL(__per_cpu_start);
 
     return 0;
 }
@@ -49,7 +49,7 @@ 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 *)(SYMBOL(__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/x86/setup.c b/xen/arch/x86/setup.c
index 06eb483..a49b16c 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -972,7 +972,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
          * respective reserve_e820_ram() invocation below.
          */
         mod[mbi->mods_count].mod_start = virt_to_mfn(_stext);
-        mod[mbi->mods_count].mod_end = __2M_rwdata_end - _stext;
+        mod[mbi->mods_count].mod_end = SYMBOL(__2M_rwdata_end) - 
SYMBOL(_stext);
     }
 
     modules_headroom = bzimage_headroom(bootstrap_map(mod), mod->mod_end);
@@ -1067,7 +1067,8 @@ void __init noreturn __start_xen(unsigned long mbi_p)
              * data until after we have switched to the relocated pagetables!
              */
             barrier();
-            move_memory(e + XEN_IMG_OFFSET, XEN_IMG_OFFSET, _end - _start, 1);
+            move_memory(e + XEN_IMG_OFFSET, XEN_IMG_OFFSET,
+                        SYMBOL(_end) - SYMBOL(_start), 1);
 
             /* Walk initial pagetables, relocating page directory entries. */
             pl4e = __va(__pa(idle_pg_table));
@@ -1382,7 +1383,8 @@ void __init noreturn __start_xen(unsigned long mbi_p)
     }
 #endif
 
-    xen_virt_end = ((unsigned long)_end + (1UL << L2_PAGETABLE_SHIFT) - 1) &
+    xen_virt_end = (SYMBOL(_end) +
+                    (1UL << L2_PAGETABLE_SHIFT) - 1) &
                    ~((1UL << L2_PAGETABLE_SHIFT) - 1);
     destroy_xen_mappings(xen_virt_end, XEN_VIRT_START + BOOTSTRAP_MAP_BASE);
 
diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index 7d1226d..07e4e1d 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -811,7 +811,8 @@ static int setup_cpu_root_pgt(unsigned int cpu)
         const char *ptr;
 
         for ( rc = 0, ptr = _stextentry;
-              !rc && ptr < _etextentry; ptr += PAGE_SIZE )
+              !rc && (unsigned long)ptr < SYMBOL(_etextentry);
+              ptr += PAGE_SIZE )
             rc = clone_mapping(ptr, rpt);
 
         if ( rc )
diff --git a/xen/drivers/vpci/vpci.c b/xen/drivers/vpci/vpci.c
index 82607bd..bc0cca6 100644
--- a/xen/drivers/vpci/vpci.c
+++ b/xen/drivers/vpci/vpci.c
@@ -33,7 +33,7 @@ struct vpci_register {
 #ifdef __XEN__
 extern vpci_register_init_t *const __start_vpci_array[];
 extern vpci_register_init_t *const __end_vpci_array[];
-#define NUM_VPCI_INIT (__end_vpci_array - __start_vpci_array)
+#define NUM_VPCI_INIT (SYMBOL(__end_vpci_array) - SYMBOL(__start_vpci_array))
 
 void vpci_remove_device(struct pci_dev *pdev)
 {
-- 
1.9.1


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