[Minios-devel] [UNIKRAFT PATCH v3 3/7] plat/kvm: Add preinit_array and init_array sections (x86)

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Adds preinit_array and init_array sections with the linker script.
Those sections are populated by the compiler/linker with function
pointer arrays. Such functions are typically part of initializing
the language runtime (e.g., C++) and have to be called early during
bootstrapping. However, they can also be used by Unikraft libraries
for early initializations (functions with constructor attribute).

Signed-off-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
---
 plat/kvm/memory.c      | 22 ++++++++++++++++------
 plat/kvm/x86/link64.ld | 18 ++++++++++++++++++
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/plat/kvm/memory.c b/plat/kvm/memory.c
index 705c6df..d2fd235 100644
--- a/plat/kvm/memory.c
+++ b/plat/kvm/memory.c
@@ -32,13 +32,13 @@ extern void *_libkvmplat_mem_end;
 
 int ukplat_memregion_count(void)
 {
-       return 6;
+       return 7;
 }
 
 int ukplat_memregion_get(int i, struct ukplat_memregion_desc *m)
 {
        extern char _text, _etext, _data, _edata, _rodata, _erodata,
-                   __bss_start, _end;
+                   _ctors, _ectors, __bss_start, _end;
        int ret;
 
        UK_ASSERT(m);
@@ -64,7 +64,17 @@ int ukplat_memregion_get(int i, struct ukplat_memregion_desc 
*m)
 #endif
                ret = 0;
                break;
-       case 2: /* data */
+       case 2: /* ctors */
+               m->base  = &_ctors;
+               m->len   = (size_t) &_ectors - (size_t) &_ctors;
+               m->flags = (UKPLAT_MEMRF_RESERVED
+                           | UKPLAT_MEMRF_READABLE);
+#if UKPLAT_MEMRNAME
+               m->name  = "ctors";
+#endif
+               ret = 0;
+               break;
+       case 3: /* data */
                m->base  = &_data;
                m->len   = (size_t) &_edata - (size_t) &_data;
                m->flags = (UKPLAT_MEMRF_RESERVED
@@ -75,7 +85,7 @@ int ukplat_memregion_get(int i, struct ukplat_memregion_desc 
*m)
 #endif
                ret = 0;
                break;
-       case 3: /* bss */
+       case 4: /* bss */
                m->base  = &__bss_start;
                m->len   = (size_t) &_end - (size_t) &__bss_start;
                m->flags = (UKPLAT_MEMRF_RESERVED
@@ -86,7 +96,7 @@ int ukplat_memregion_get(int i, struct ukplat_memregion_desc 
*m)
 #endif
                ret = 0;
                break;
-       case 4: /* heap */
+       case 5: /* heap */
                m->base  = _libkvmplat_heap_start;
                m->len   = (size_t) _libkvmplat_stack_top
                           - (size_t) _libkvmplat_heap_start;
@@ -96,7 +106,7 @@ int ukplat_memregion_get(int i, struct ukplat_memregion_desc 
*m)
 #endif
                ret = 0;
                break;
-       case 5: /* stack */
+       case 6: /* stack */
                m->base  = _libkvmplat_stack_top;
                m->len   = (size_t) _libkvmplat_mem_end
                           - (size_t) _libkvmplat_stack_top;
diff --git a/plat/kvm/x86/link64.ld b/plat/kvm/x86/link64.ld
index a9f3ac3..d1bfa73 100644
--- a/plat/kvm/x86/link64.ld
+++ b/plat/kvm/x86/link64.ld
@@ -50,6 +50,24 @@ SECTIONS
        }
        _erodata = .;
 
+       /* Constructor tables (read-only) */
+       _ctors = .;
+       .preinit_array : {
+               . = ALIGN(0x8);
+               PROVIDE_HIDDEN (__preinit_array_start = .);
+               KEEP (*(.preinit_array))
+               PROVIDE_HIDDEN (__preinit_array_end = .);
+       }
+
+       .init_array : {
+               . = ALIGN(0x8);
+               PROVIDE_HIDDEN (__init_array_start = .);
+               KEEP (*(SORT_BY_INIT_PRIORITY(.init_array.*) 
SORT_BY_INIT_PRIORITY(.ctors.*)))
+               KEEP (*(.init_array .ctors))
+               PROVIDE_HIDDEN (__init_array_end = .);
+       }
+       _ectors = .;
+
        /* Read-write data (initialized) */
        . = ALIGN(0x1000);
        _data = .;
-- 
2.7.4


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