dl_iterate_phdr

53d7ac6f · Nickolai Zeldovich · 3f3c2501 · 53d7ac6f · 53d7ac6f · 53d7ac6f
--- a/kernel/boot.S
+++ b/kernel/boot.S
@@ -33,7 +33,7 @@ multiboot_header:
 	.long flags
 	.long (- magic - flags)               # checksum
 	.long PADDR(multiboot_header)         # header address
-	.long PADDR(multiboot_header)  # load address
+	.long PADDR(multiboot_header)-0x1000  # load address, incl elf headers
 	.long PADDR(edata)                    # load end address
 	.long PADDR(end)                      # bss end address
 	.long PADDR(start)                    # entry address

--- a/kernel/cpprt.cc
+++ b/kernel/cpprt.cc
@@ -6,6 +6,7 @@
 #include "condvar.h"
 #include "proc.hh"
 #include "cpu.hh"
+#include "elf.hh"

 void*
 operator new(unsigned long nbytes)
@@ -159,11 +160,34 @@ free(void* vp)
  kmfree(p-1, p[-1]+8);
 }

-extern "C" int dl_iterate_phdr(void);
+struct dl_phdr_info {
+  Elf64_Addr dlpi_addr;
+  const char *dlpi_name;
+  const struct proghdr *dlpi_phdr;
+  Elf64_Half dlpi_phnum;
+  unsigned long long int dlpi_adds;
+  unsigned long long int dlpi_subs;
+};
+
+extern "C" int dl_iterate_phdr(int (*cb) (struct dl_phdr_info *info,
+                                          size_t size, void *data),
+                               void *data);
 int
-dl_iterate_phdr(void)
-{
-  return -1;
+dl_iterate_phdr(int (*cb) (struct dl_phdr_info *info, size_t size, void *data),
+                void *data)
+{
+  extern char multiboot_header[];
+  elfhdr *eh = (elfhdr*) &multiboot_header[-0x1000];
+  assert(eh->magic == ELF_MAGIC);
+
+  struct dl_phdr_info info;
+  info.dlpi_addr = 0;
+  info.dlpi_name = "kernel";
+  info.dlpi_phdr = (proghdr*) (((char*) eh) + eh->phoff);
+  info.dlpi_phnum = eh->phnum;
+  info.dlpi_adds = 0;
+  info.dlpi_subs = 0;
+  return cb(&info, sizeof(struct dl_phdr_info), data);
 }

 extern "C" void __stack_chk_fail(void);

--- a/kernel/kernel.ld
+++ b/kernel/kernel.ld
@@ -4,9 +4,12 @@ ENTRY(xxx)

 SECTIONS
 {
-	. = 0xFFFFFFFFC0100000;
+        /* Skip one page to leave room for ELF headers.
+         * See multiboot_header and dl_iterate_phdr.
+         */
+	. = 0xFFFFFFFFC0101000;
 	PROVIDE(text = .);
-	.text : AT(0x100000) {
+	.text : AT(0x101000) {
 		*(.text .stub .text.* .gnu.linkonce.t.*)
 	}
 	.rodata : {