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* [RFC]: win32-nat.c better handling of DLL relocation
@ 2003-01-11 15:51 Raoul Gough
  2003-01-11 17:23 ` Christopher Faylor
  0 siblings, 1 reply; 7+ messages in thread
From: Raoul Gough @ 2003-01-11 15:51 UTC (permalink / raw)
  To: gdb-patches

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win32-nat.c currently only passes the loaded address of the .text
section into symbol_file_add, which means that any symbols from .data
or .bss don't get fixed up properly. This patch fixes the problem by
calculating the load addresses of all sections known to bfd.

I recently posted a test case which demonstrates the relocation
problem in the "coffread.c extension" thread (message ID
avejk1$lv6$1@main.gmane.org, posted 7 Jan 2003 13:10:49 -0000). This
showed that gdb 5.2.1 didn't handle any DLL symbol relocations. The
current CVS version only handles the .text section. With this patch,
it handles all sections correctly.

Raoul Gough.

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2003-01-10  Raoul Gough  <RaoulGough@yahoo.co.uk>

 	* win32-nat.c(get_relocated_section_addrs): New function. Find
	section load addresses for symbol handling in relocated DLLs.
	(solib_symbols_add): Open a bfd and call get_relocated_section_addrs.

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Index: win32-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/win32-nat.c,v
retrieving revision 1.66
diff -c -p -r1.66 win32-nat.c
*** win32-nat.c	23 Nov 2002 02:49:45 -0000	1.66
--- win32-nat.c	11 Jan 2003 15:49:38 -0000
*************** child_clear_solibs (void)
*** 750,761 ****
    solib_end = &solib_start;
    max_dll_name_len = sizeof ("DLL Name") - 1;
  }
  
  /* Add DLL symbol information. */
  static struct objfile *
  solib_symbols_add (char *name, int from_tty, CORE_ADDR load_addr)
  {
!   struct section_addr_info section_addrs;
  
    /* The symbols in a dll are offset by 0x1000, which is the
       the offset from 0 of the first byte in an image - because
--- 750,816 ----
    solib_end = &solib_start;
    max_dll_name_len = sizeof ("DLL Name") - 1;
  }
+ \f
+ /* Get the loaded address of all sections, given that .text was loaded
+    at text_load. Assumes that all sections are subject to the same
+    relocation offset. Returns NULL if problems occur or if the
+    sections were not relocated. */
  
+ static struct section_addr_info *
+ get_relocated_section_addrs (bfd *abfd, CORE_ADDR text_load)
+ {
+   struct section_addr_info *result = NULL;
+   int section_count = bfd_count_sections (abfd);
+   asection *text_section = bfd_get_section_by_name (abfd, ".text");
+   CORE_ADDR text_vma;
+ 
+   if (!text_section)
+     {
+       /* Couldn't get the .text section. Weird. */
+     }
+ 
+   else if (text_load == (text_vma = bfd_get_section_vma (abfd, text_section)))
+     {
+       /* DLL wasn't relocated. */
+     }
+ 
+   else
+     {
+       /* Figure out all sections' loaded addresses. The offset here is
+ 	 such that taking a bfd_get_section_vma() result and adding
+ 	 offset will give the real load address of the section. */
+ 
+       CORE_ADDR offset = text_load - text_vma;
+ 
+       struct section_table *table_start = NULL;
+       struct section_table *table_end = NULL;
+       struct section_table *iter = NULL;
+ 
+       build_section_table (abfd, &table_start, &table_end);
+ 
+       for (iter = table_start; iter < table_end; ++iter)
+ 	{
+ 	  /* Relocated addresses. */
+ 	  iter->addr += offset;
+ 	  iter->endaddr += offset;
+ 	}
+ 
+       result = build_section_addr_info_from_section_table (table_start,
+ 							   table_end);
+ 
+       xfree (table_start);
+     }
+ 
+   return result;
+ }
+ \f
  /* Add DLL symbol information. */
  static struct objfile *
  solib_symbols_add (char *name, int from_tty, CORE_ADDR load_addr)
  {
!   struct section_addr_info *section_addrs_ptr = NULL;
!   static struct objfile *result = NULL;
!   bfd *abfd = NULL;
  
    /* The symbols in a dll are offset by 0x1000, which is the
       the offset from 0 of the first byte in an image - because
*************** solib_symbols_add (char *name, int from_
*** 764,773 ****
    if (!name || !name[0])
      return NULL;
  
!   memset (&section_addrs, 0, sizeof (section_addrs));
!   section_addrs.other[0].name = ".text";
!   section_addrs.other[0].addr = load_addr;
!   return safe_symbol_file_add (name, from_tty, &section_addrs, 0, OBJF_SHARED);
  }
  
  /* Load DLL symbol info. */
--- 819,864 ----
    if (!name || !name[0])
      return NULL;
  
!   abfd = bfd_openr (name, "pei-i386");
! 
!   if (!abfd)
!     {
!       /* pei failed - try pe */
!       abfd = bfd_openr (name, "pe-i386");
!     }
! 
!   if (abfd)
!     {
!       if (bfd_check_format (abfd, bfd_object))
! 	{
! 	  section_addrs_ptr = get_relocated_section_addrs (abfd, load_addr);
! 	}
! 
!       bfd_close (abfd);
!     }
! 
!   if (section_addrs_ptr)
!     {
!       result = safe_symbol_file_add (name, from_tty, section_addrs_ptr,
! 				     0, OBJF_SHARED);
! 
!       free_section_addr_info (section_addrs_ptr);
!     }
! 
!   else
!     {
!       /* Fallback on handling just the .text section. */
!       struct section_addr_info section_addrs;
! 
!       memset (&section_addrs, 0, sizeof (section_addrs));
!       section_addrs.other[0].name = ".text";
!       section_addrs.other[0].addr = load_addr;
! 
!       result = safe_symbol_file_add (name, from_tty, &section_addrs,
! 				     0, OBJF_SHARED);
!     }
! 
!   return result;
  }
  
  /* Load DLL symbol info. */

^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2003-02-06 19:51 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2003-01-11 15:51 [RFC]: win32-nat.c better handling of DLL relocation Raoul Gough
2003-01-11 17:23 ` Christopher Faylor
2003-01-11 18:18   ` Raoul Gough
2003-01-29 15:20   ` Christopher Faylor
2003-01-29 18:26     ` Raoul Gough
2003-02-06 19:31     ` Raoul Gough
2003-02-06 19:51       ` Christopher Faylor

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