[Xen-devel] [PATCH v10 4/6] xen/x86: use DEFINE_SYMBOL as required

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

Use SYMBOLS_SUBTRACT and SYMBOLS_COMPARE in cases of comparisons and
subtractions of:

__2M_rwdata_start, __2M_rwdata_end, __end_vpci_array,
__start_vpci_array, _stextentry, _etextentry, __trampoline_rel_start,
__trampoline_rel_stop, __trampoline_seg_start, __trampoline_seg_stop
__per_cpu_start, __per_cpu_data_end

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

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/x86/alternative.c   |  8 +++++++-
 xen/arch/x86/efi/efi-boot.h  | 10 ++++++----
 xen/arch/x86/percpu.c        |  9 +++++----
 xen/arch/x86/setup.c         |  7 +++++--
 xen/arch/x86/smpboot.c       |  5 +++--
 xen/drivers/vpci/vpci.c      |  6 +++---
 xen/include/asm-x86/percpu.h |  4 +++-
 7 files changed, 32 insertions(+), 17 deletions(-)

diff --git a/xen/arch/x86/alternative.c b/xen/arch/x86/alternative.c
index b8c819a..f81759f 100644
--- a/xen/arch/x86/alternative.c
+++ b/xen/arch/x86/alternative.c
@@ -29,6 +29,10 @@
 
 #define MAX_PATCH_LEN (255-1)
 
+/*
+ * Cannot use DEFINE_SYMBOL because of the way they are passed to
+ * apply_alternatives.
+ */
 extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
 
 #ifdef K8_NOP1
@@ -193,8 +197,10 @@ 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.
+     *
+     * start and end could be pointers to different objects.
      */
-    for ( a = base = start; a < end; a++ )
+    for ( a = base = start; (uintptr_t)a < (uintptr_t)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..f798b7b 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -98,8 +98,10 @@ static void __init efi_arch_relocate_image(unsigned long 
delta)
     }
 }
 
-extern const s32 __trampoline_rel_start[], __trampoline_rel_stop[];
-extern const s32 __trampoline_seg_start[], __trampoline_seg_stop[];
+DEFINE_SYMBOL(s32, trampoline_rel, __trampoline_rel_start,
+              __trampoline_rel_stop);
+DEFINE_SYMBOL(s32, trampoline_seg, __trampoline_seg_start,
+              __trampoline_seg_stop);
 
 static void __init relocate_trampoline(unsigned long phys)
 {
@@ -112,11 +114,11 @@ static void __init relocate_trampoline(unsigned long phys)
 
     /* Apply relocations to trampoline. */
     for ( trampoline_ptr = __trampoline_rel_start;
-          trampoline_ptr < __trampoline_rel_stop;
+          trampoline_rel_lt(trampoline_ptr, __trampoline_rel_stop);
           ++trampoline_ptr )
         *(u32 *)(*trampoline_ptr + (long)trampoline_ptr) += phys;
     for ( trampoline_ptr = __trampoline_seg_start;
-          trampoline_ptr < __trampoline_seg_stop;
+          trampoline_seg_lt(trampoline_ptr, __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..2efb180 100644
--- a/xen/arch/x86/percpu.c
+++ b/xen/arch/x86/percpu.c
@@ -13,7 +13,8 @@ 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(per_cpu_diff(__per_cpu_start,     \
+                                                       __per_cpu_data_end))
 
 void __init percpu_init_areas(void)
 {
@@ -33,8 +34,8 @@ 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, per_cpu_diff(__per_cpu_start, __per_cpu_data_end));
+    __per_cpu_offset[cpu] = (uintptr_t)p - (uintptr_t)__per_cpu_start;
 
     return 0;
 }
@@ -49,7 +50,7 @@ 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/x86/setup.c b/xen/arch/x86/setup.c
index 06eb483..b024339 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -252,7 +252,8 @@ void __init discard_initial_images(void)
     initial_images = NULL;
 }
 
-extern char __init_begin[], __init_end[], __bss_start[], __bss_end[];
+DEFINE_SYMBOL(char, init, __init_begin, __init_end);
+extern char __bss_start[], __bss_end[];
 
 static void __init init_idle_domain(void)
 {
@@ -600,7 +601,9 @@ static void noinline init_done(void)
     unregister_init_virtual_region();
 
     /* Zero the .init code and data. */
-    for ( va = __init_begin; va < _p(__init_end); va += PAGE_SIZE )
+    for ( va = (char *)__init_begin;
+          init_lt(va, __init_end);
+          va += PAGE_SIZE )
         clear_page(va);
 
     /* Destroy Xen's mappings, and reuse the pages. */
diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index 7d1226d..b51bead 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -782,7 +782,7 @@ DEFINE_PER_CPU(root_pgentry_t *, root_pgt);
 
 static root_pgentry_t common_pgt;
 
-extern const char _stextentry[], _etextentry[];
+DEFINE_SYMBOL(char, textentry, _stextentry, _etextentry);
 
 static int setup_cpu_root_pgt(unsigned int cpu)
 {
@@ -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 && textentry_lt(ptr, _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..1ea6d7f 100644
--- a/xen/drivers/vpci/vpci.c
+++ b/xen/drivers/vpci/vpci.c
@@ -31,9 +31,9 @@ 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_SYMBOL(vpci_register_init_t *const, vpci_array, __start_vpci_array,
+              __end_vpci_array);
+#define NUM_VPCI_INIT (vpci_array_diff(__start_vpci_array, __end_vpci_array))
 
 void vpci_remove_device(struct pci_dev *pdev)
 {
diff --git a/xen/include/asm-x86/percpu.h b/xen/include/asm-x86/percpu.h
index 51562b9..8778ed1 100644
--- a/xen/include/asm-x86/percpu.h
+++ b/xen/include/asm-x86/percpu.h
@@ -2,7 +2,9 @@
 #define __X86_PERCPU_H__
 
 #ifndef __ASSEMBLY__
-extern char __per_cpu_start[], __per_cpu_data_end[];
+#include <xen/types.h>
+
+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);
 #endif
-- 
1.9.1


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