[PATCH v8 2/7] xen: use start_, end_, and more

[Stefano Stabellini <sstabellini@kernel.org>]

Start making use of the following uintptr_t variables:

start_, end_, stext_, etext_, stextentry_, etextentry_,
srodata_, erodata_, _sinittext, _einittext

Replacing the corresponding linker symbols. It is done to avoid
comparing and subtracting pointers pointing to different objects.

This patch carries one functional change: core.start/end and
core_init.start/end are now initialized in setup_virtual_regions,
because stext_ & friends are not constant anymore (initializer element
is not constant).

Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
---
Changes in v8:
- remove SYMBOL_HIDE
- use new symbol names
- changes are split differently across the patches
---
 xen/arch/arm/alternative.c          |  6 +++---
 xen/arch/arm/arm32/livepatch.c      |  3 ++-
 xen/arch/arm/arm64/livepatch.c      |  3 ++-
 xen/arch/arm/domain_build.c         |  2 +-
 xen/arch/arm/livepatch.c            |  5 +++--
 xen/arch/arm/setup.c                |  5 +++--
 xen/arch/x86/setup.c                | 17 ++++++++---------
 xen/arch/x86/smpboot.c              |  7 ++++---
 xen/arch/x86/tboot.c                |  4 ++--
 xen/arch/x86/x86_64/machine_kexec.c |  4 ++--
 xen/common/symbols.c                |  3 +--
 xen/common/virtual_region.c         |  9 +++++----
 xen/include/asm-arm/grant_table.h   |  2 +-
 xen/include/asm-arm/mm.h            |  4 ++--
 xen/include/asm-x86/mm.h            |  2 +-
 xen/include/xen/kernel.h            | 32 ++++++++++++++++----------------
 16 files changed, 56 insertions(+), 52 deletions(-)

diff --git a/xen/arch/arm/alternative.c b/xen/arch/arm/alternative.c
index 52ed7ed..b79536d 100644
--- a/xen/arch/arm/alternative.c
+++ b/xen/arch/arm/alternative.c
@@ -187,8 +187,8 @@ static int __apply_alternatives_multi_stop(void *unused)
     {
         int ret;
         struct alt_region region;
-        mfn_t xen_mfn = virt_to_mfn(_start);
-        paddr_t xen_size = _end - _start;
+        mfn_t xen_mfn = virt_to_mfn(start_);
+        paddr_t xen_size = end_ - start_;
         unsigned int xen_order = get_order_from_bytes(xen_size);
         void *xenmap;
 
@@ -206,7 +206,7 @@ static int __apply_alternatives_multi_stop(void *unused)
         region.begin = __alt_instructions;
         region.end = __alt_instructions_end;
 
-        ret = __apply_alternatives(&region, xenmap - (void *)_start);
+        ret = __apply_alternatives(&region, (uintptr_t)xenmap - start_);
         /* The patching is not expected to fail during boot. */
         BUG_ON(ret != 0);
 
diff --git a/xen/arch/arm/arm32/livepatch.c b/xen/arch/arm/arm32/livepatch.c
index 41378a5..db9a3f4 100644
--- a/xen/arch/arm/arm32/livepatch.c
+++ b/xen/arch/arm/arm32/livepatch.c
@@ -56,7 +56,8 @@ void arch_livepatch_apply(struct livepatch_func *func)
     else
         insn = 0xe1a00000; /* mov r0, r0 */
 
-    new_ptr = func->old_addr - (void *)_start + vmap_of_xen_text;
+    new_ptr = (uint32_t *)((uintptr_t)func->old_addr -
+              start_ + (uintptr_t)vmap_of_xen_text);
     len = len / sizeof(uint32_t);
 
     /* PATCH! */
diff --git a/xen/arch/arm/arm64/livepatch.c b/xen/arch/arm/arm64/livepatch.c
index 2247b92..a18d25d 100644
--- a/xen/arch/arm/arm64/livepatch.c
+++ b/xen/arch/arm/arm64/livepatch.c
@@ -43,7 +43,8 @@ void arch_livepatch_apply(struct livepatch_func *func)
     /* Verified in livepatch_verify_distance. */
     ASSERT(insn != AARCH64_BREAK_FAULT);
 
-    new_ptr = func->old_addr - (void *)_start + vmap_of_xen_text;
+    new_ptr = (uint32_t *)((uintptr_t)func->old_addr -
+              start_ + (uintptr_t)vmap_of_xen_text);
     len = len / sizeof(uint32_t);
 
     /* PATCH! */
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index d2c63a8..455b0f2 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -1904,7 +1904,7 @@ static void __init find_gnttab_region(struct domain *d,
      * Only use the text section as it's always present and will contain
      * enough space for a large grant table
      */
-    kinfo->gnttab_start = __pa(_stext);
+    kinfo->gnttab_start = __pa(stext_);
     kinfo->gnttab_size = gnttab_dom0_frames() << PAGE_SHIFT;
 
 #ifdef CONFIG_ARM_32
diff --git a/xen/arch/arm/livepatch.c b/xen/arch/arm/livepatch.c
index 279d52c..3f12c8e 100644
--- a/xen/arch/arm/livepatch.c
+++ b/xen/arch/arm/livepatch.c
@@ -27,7 +27,7 @@ int arch_livepatch_quiesce(void)
         return -EINVAL;
 
     text_mfn = virt_to_mfn(_start);
-    text_order = get_order_from_bytes(_end - _start);
+    text_order = get_order_from_bytes(end_ - start_);
 
     /*
      * The text section is read-only. So re-map Xen to be able to patch
@@ -78,7 +78,8 @@ void arch_livepatch_revert(const struct livepatch_func *func)
     uint32_t *new_ptr;
     unsigned int len;
 
-    new_ptr = func->old_addr - (void *)_start + vmap_of_xen_text;
+    new_ptr = (uint32_t *)((uintptr_t)func->old_addr -
+              start_ + (uintptr_t)vmap_of_xen_text);
 
     len = livepatch_insn_len(func);
     memcpy(new_ptr, func->opaque, len);
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 444857a..83e29ff 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -772,8 +772,9 @@ void __init start_xen(unsigned long boot_phys_offset,
 
     /* Register Xen's load address as a boot module. */
     xen_bootmodule = add_boot_module(BOOTMOD_XEN,
-                             (paddr_t)(uintptr_t)(_start + boot_phys_offset),
-                             (paddr_t)(uintptr_t)(_end - _start + 1), false);
+                                     start_ + boot_phys_offset,
+                                     end_ - start_ + 1,
+                                     false);
     BUG_ON(!xen_bootmodule);
 
     setup_pagetables(boot_phys_offset);
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 06eb483..34949fc4 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -971,8 +971,8 @@ void __init noreturn __start_xen(unsigned long mbi_p)
          * This needs to remain in sync with xen_in_range() and the
          * 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_start = virt_to_mfn(stext_);
+        mod[mbi->mods_count].mod_end = (uintptr_t)__2M_rwdata_end - stext_;
     }
 
     modules_headroom = bzimage_headroom(bootstrap_map(mod), mod->mod_end);
@@ -1039,7 +1039,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
          * Is the region size greater than zero and does it begin
          * at or above the end of current Xen image placement?
          */
-        if ( (end > s) && (end - reloc_size + XEN_IMG_OFFSET >= __pa(_end)) )
+        if ( (end > s) && (end - reloc_size + XEN_IMG_OFFSET >= __pa(end_)) )
         {
             l4_pgentry_t *pl4e;
             l3_pgentry_t *pl3e;
@@ -1067,7 +1067,7 @@ 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, end_ - start_, 1);
 
             /* Walk initial pagetables, relocating page directory entries. */
             pl4e = __va(__pa(idle_pg_table));
@@ -1108,8 +1108,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
              * is contained in this PTE.
              */
             BUG_ON(using_2M_mapping() &&
-                   l2_table_offset((unsigned long)_erodata) ==
-                   l2_table_offset((unsigned long)_stext));
+                   l2_table_offset(erodata_) == l2_table_offset(stext_));
             *pl2e++ = l2e_from_pfn(xen_phys_start >> PAGE_SHIFT,
                                    PAGE_HYPERVISOR_RX | _PAGE_PSE);
             for ( i = 1; i < L2_PAGETABLE_ENTRIES; i++, pl2e++ )
@@ -1239,7 +1238,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
         panic("Not enough memory to relocate Xen\n");
 
     /* This needs to remain in sync with xen_in_range(). */
-    reserve_e820_ram(&boot_e820, __pa(_stext), __pa(__2M_rwdata_end));
+    reserve_e820_ram(&boot_e820, __pa(stext_), __pa(__2M_rwdata_end));
 
     /* Late kexec reservation (dynamic start address). */
     kexec_reserve_area(&boot_e820);
@@ -1382,7 +1381,7 @@ void __init noreturn __start_xen(unsigned long mbi_p)
     }
 #endif
 
-    xen_virt_end = ((unsigned long)_end + (1UL << L2_PAGETABLE_SHIFT) - 1) &
+    xen_virt_end = (end_ + (1UL << L2_PAGETABLE_SHIFT) - 1) &
                    ~((1UL << L2_PAGETABLE_SHIFT) - 1);
     destroy_xen_mappings(xen_virt_end, XEN_VIRT_START + BOOTSTRAP_MAP_BASE);
 
@@ -1871,7 +1870,7 @@ int __hwdom_init xen_in_range(unsigned long mfn)
          */
 
         /* hypervisor .text + .rodata */
-        xen_regions[region_ro].s = __pa(&_stext);
+        xen_regions[region_ro].s = __pa(stext_);
         xen_regions[region_ro].e = __pa(&__2M_rodata_end);
         /* hypervisor .data + .bss */
         xen_regions[region_rw].s = __pa(&__2M_rwdata_start);
diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index 7d1226d..44fae91 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[];
+extern uintptr_t stextentry_, etextentry_;
 
 static int setup_cpu_root_pgt(unsigned int cpu)
 {
@@ -810,8 +810,9 @@ static int setup_cpu_root_pgt(unsigned int cpu)
     {
         const char *ptr;
 
-        for ( rc = 0, ptr = _stextentry;
-              !rc && ptr < _etextentry; ptr += PAGE_SIZE )
+        for ( rc = 0, ptr = (const char *)stextentry_;
+              !rc && (uintptr_t)ptr < etextentry_;
+              ptr += PAGE_SIZE )
             rc = clone_mapping(ptr, rpt);
 
         if ( rc )
diff --git a/xen/arch/x86/tboot.c b/xen/arch/x86/tboot.c
index f3fdee4..620303e 100644
--- a/xen/arch/x86/tboot.c
+++ b/xen/arch/x86/tboot.c
@@ -373,9 +373,9 @@ void tboot_shutdown(uint32_t shutdown_type)
         g_tboot_shared->mac_regions[0].size = bootsym_phys(trampoline_end) -
                                               bootsym_phys(trampoline_start);
         /* hypervisor .text + .rodata */
-        g_tboot_shared->mac_regions[1].start = (uint64_t)__pa(&_stext);
+        g_tboot_shared->mac_regions[1].start = (uint64_t)__pa(stext_);
         g_tboot_shared->mac_regions[1].size = __pa(&__2M_rodata_end) -
-                                              __pa(&_stext);
+                                              __pa(stext_);
         /* hypervisor .data + .bss */
         g_tboot_shared->mac_regions[2].start = (uint64_t)__pa(&__2M_rwdata_start);
         g_tboot_shared->mac_regions[2].size = __pa(&__2M_rwdata_end) -
diff --git a/xen/arch/x86/x86_64/machine_kexec.c b/xen/arch/x86/x86_64/machine_kexec.c
index f4a005c..cf435ac 100644
--- a/xen/arch/x86/x86_64/machine_kexec.c
+++ b/xen/arch/x86/x86_64/machine_kexec.c
@@ -13,8 +13,8 @@
 
 int machine_kexec_get_xen(xen_kexec_range_t *range)
 {
-        range->start = virt_to_maddr(_start);
-        range->size = virt_to_maddr(_end) - (unsigned long)range->start;
+        range->start = virt_to_maddr(start_);
+        range->size = virt_to_maddr(end_) - (unsigned long)range->start;
         return 0;
 }
 
diff --git a/xen/common/symbols.c b/xen/common/symbols.c
index 9377f41..b6cf0dd 100644
--- a/xen/common/symbols.c
+++ b/xen/common/symbols.c
@@ -149,8 +149,7 @@ const char *symbols_lookup(unsigned long addr,
 
     /* if we found no next symbol, we use the end of the section */
     if (!symbol_end)
-        symbol_end = is_kernel_inittext(addr) ?
-            (unsigned long)_einittext : (unsigned long)_etext;
+        symbol_end = is_kernel_inittext(addr) ? einittext_ : etext_;
 
     *symbolsize = symbol_end - symbols_address(low);
     *offset = addr - symbols_address(low);
diff --git a/xen/common/virtual_region.c b/xen/common/virtual_region.c
index aa23918..1637453 100644
--- a/xen/common/virtual_region.c
+++ b/xen/common/virtual_region.c
@@ -10,15 +10,11 @@
 
 static struct virtual_region core = {
     .list = LIST_HEAD_INIT(core.list),
-    .start = _stext,
-    .end = _etext,
 };
 
 /* Becomes irrelevant when __init sections are cleared. */
 static struct virtual_region core_init __initdata = {
     .list = LIST_HEAD_INIT(core_init.list),
-    .start = _sinittext,
-    .end = _einittext,
 };
 
 /*
@@ -114,6 +110,11 @@ void __init setup_virtual_regions(const struct exception_table_entry *start,
         NULL
     };
 
+    core.start = (char *)start_;
+    core.end = (char *)end_;
+    core_init.start = (char *)sinittext_;
+    core_init.end = (char *)einittext_;
+
     for ( i = 1; bug_frames[i]; i++ )
     {
         const struct bug_frame *s;
diff --git a/xen/include/asm-arm/grant_table.h b/xen/include/asm-arm/grant_table.h
index 816e3c6..74a8ef4 100644
--- a/xen/include/asm-arm/grant_table.h
+++ b/xen/include/asm-arm/grant_table.h
@@ -31,7 +31,7 @@ void gnttab_mark_dirty(struct domain *d, mfn_t mfn);
  * enough space for a large grant table
  */
 #define gnttab_dom0_frames()                                             \
-    min_t(unsigned int, opt_max_grant_frames, PFN_DOWN(_etext - _stext))
+    min_t(unsigned int, opt_max_grant_frames, PFN_DOWN(etext_ - stext_))
 
 #define gnttab_init_arch(gt)                                             \
 ({                                                                       \
diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
index eafa26f..e72ffb2 100644
--- a/xen/include/asm-arm/mm.h
+++ b/xen/include/asm-arm/mm.h
@@ -151,8 +151,8 @@ extern vaddr_t xenheap_virt_start;
 #endif
 
 #define is_xen_fixed_mfn(mfn)                                   \
-    ((pfn_to_paddr(mfn) >= virt_to_maddr(&_start)) &&       \
-     (pfn_to_paddr(mfn) <= virt_to_maddr(&_end)))
+    ((pfn_to_paddr(mfn) >= virt_to_maddr(&start_)) &&       \
+     (pfn_to_paddr(mfn) <= virt_to_maddr(&end_)))
 
 #define page_get_owner(_p)    (_p)->v.inuse.domain
 #define page_set_owner(_p,_d) ((_p)->v.inuse.domain = (_d))
diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
index 6faa563..3b07d12 100644
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -280,7 +280,7 @@ struct page_info
 #define is_xen_heap_mfn(mfn) \
     (__mfn_valid(mfn) && is_xen_heap_page(mfn_to_page(_mfn(mfn))))
 #define is_xen_fixed_mfn(mfn)                     \
-    ((((mfn) << PAGE_SHIFT) >= __pa(&_stext)) &&  \
+    ((((mfn) << PAGE_SHIFT) >= __pa(stext_)) &&  \
      (((mfn) << PAGE_SHIFT) <= __pa(&__2M_rwdata_end)))
 
 #define PRtype_info "016lx"/* should only be used for printk's */
diff --git a/xen/include/xen/kernel.h b/xen/include/xen/kernel.h
index 548b64d..78643a9 100644
--- a/xen/include/xen/kernel.h
+++ b/xen/include/xen/kernel.h
@@ -65,28 +65,28 @@
 	1;                                      \
 })
 
-extern char _start[], _end[], start[];
-#define is_kernel(p) ({                         \
-    char *__p = (char *)(unsigned long)(p);     \
-    (__p >= _start) && (__p < _end);            \
+extern uintptr_t start_, end_;
+#define is_kernel(p) ({                                             \
+    const uintptr_t p__ = (const uintptr_t)(p);                     \
+    (p__ >= start_) && (p__ < end_);      \
 })
 
-extern char _stext[], _etext[];
-#define is_kernel_text(p) ({                    \
-    char *__p = (char *)(unsigned long)(p);     \
-    (__p >= _stext) && (__p < _etext);          \
+extern uintptr_t stext_, etext_;
+#define is_kernel_text(p) ({                                        \
+    const uintptr_t p__ = (const uintptr_t)(p);                     \
+    (p__ >= stext_) && (p__ < etext_);                              \
 })
 
-extern const char _srodata[], _erodata[];
-#define is_kernel_rodata(p) ({                  \
-    const char *__p = (const char *)(unsigned long)(p);     \
-    (__p >= _srodata) && (__p < _erodata);      \
+extern uintptr_t srodata_, erodata_;
+#define is_kernel_rodata(p) ({                                      \
+    const uintptr_t p__ = (const uintptr_t)(p);                     \
+    (p__ >= srodata_) && (p__ < erodata_);                          \
 })
 
-extern char _sinittext[], _einittext[];
-#define is_kernel_inittext(p) ({                \
-    char *__p = (char *)(unsigned long)(p);     \
-    (__p >= _sinittext) && (__p < _einittext);  \
+extern uintptr_t sinittext_, einittext_;
+#define is_kernel_inittext(p) ({                                         \
+    const uintptr_t p__ = (const uintptr_t)(p);                          \
+    (p__ >= sinittext_) && (p__ < einittext_);                           \
 })
 
 extern enum system_state {
-- 
1.9.1


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