With the patches pasted below, a dll linked with the full mingw
runtime loaded successfully for me.
On Thursday 31 December 2009 18:06:36, Pedro Alves wrote:
> On Thursday 31 December 2009 17:32:02, Danny Backx wrote:
> > On Thu, 2009-12-31 at 16:11 +0000, Pedro Alves wrote:
> > > And, I'm using ld's --defsym switch to define it.
> >
> > > It looks like Windows Mobile 6.1's loader is darn strict WRT
> > > to base relocations, and we'll have to figure out a different
> > > way to get at the runtime image base.
> >
> > A variation of what both you and I have tried should do the trick,
> > shouldn't it ?
> >
> > Based on the values in your example :
> > - we can't pass __image_base__ = 0x010000
> > - but we can pass 0x011000 == &DllMainCRTStartup
> > then all the additional info we need is 0x01000 (BaseOfCode).
>
> Yes, but this patch instead should be quite upstreamable:
>
> Index: binutils/ld/scripttempl/pe.sc
> ===================================================================
> --- binutils.orig/ld/scripttempl/pe.sc 2009-12-31 17:50:54.000000000 +0000
> +++ binutils/ld/scripttempl/pe.sc 2009-12-31 17:52:29.000000000 +0000
> @@ -70,6 +70,7 @@ SECTIONS
> ${RELOCATING+. = ALIGN(__section_alignment__);}
> .text ${RELOCATING+ __image_base__ + ( __section_alignment__ <
> ${TARGET_PAGE_SIZE} ? . : __section_alignment__ )} :
> {
> + ${RELOCATING+__text_start__ = . ;}
> ${RELOCATING+ *(.init)}
> *(.text)
> ${R_TEXT}
> @@ -85,6 +86,7 @@ SECTIONS
> ${RELOCATING+ *(.gcc_exc)}
> ${RELOCATING+PROVIDE (etext = .);}
> ${RELOCATING+ *(.gcc_except_table)}
> + ${RELOCATING+__text_end__ = . ;}
> }
>
> /* The Cygwin32 library uses a section to avoid copying certain data
>
> There are already __data_start__, __data_end__ and
> __bss_start__, __bss_end__ symbols, only text range is missing.
>
> For the 0x01000, we could just hardcode it. In practice, this is
> the usual size of the PE headers. Can an image have a bigger header
> than that, in practice? Or are the variable size bits all in
> idata, edata, etc., which end up in allocated section? I know that
> gdb hardcodes the 0x1000 (src/gdb/windows-nat.c).
>
> I don't think it is possible on Windows CE to read the
> IMAGE_OPTIONAL_HEADER and friends from DllMainCRTStartup, starting from
> the passed in handle? We could get at the image base that way, but
> I think that's only possible on non-CE Windows. Am I wrong?
>
--
Pedro Alves
2009-12-31 Pedro Alves <[email protected]>
ld/
scripttempl/pe.sc: Define __text_start__ and __text_end__.
---
ld/scripttempl/pe.sc | 2 ++
1 file changed, 2 insertions(+)
Index: binutils/ld/scripttempl/pe.sc
===================================================================
--- binutils.orig/ld/scripttempl/pe.sc 2009-12-31 17:50:54.000000000 +0000
+++ binutils/ld/scripttempl/pe.sc 2009-12-31 17:52:29.000000000 +0000
@@ -70,6 +70,7 @@ SECTIONS
${RELOCATING+. = ALIGN(__section_alignment__);}
.text ${RELOCATING+ __image_base__ + ( __section_alignment__ <
${TARGET_PAGE_SIZE} ? . : __section_alignment__ )} :
{
+ ${RELOCATING+__text_start__ = . ;}
${RELOCATING+ *(.init)}
*(.text)
${R_TEXT}
@@ -85,6 +86,7 @@ SECTIONS
${RELOCATING+ *(.gcc_exc)}
${RELOCATING+PROVIDE (etext = .);}
${RELOCATING+ *(.gcc_except_table)}
+ ${RELOCATING+__text_end__ = . ;}
}
/* The Cygwin32 library uses a section to avoid copying certain data
===================================================================
2009-12-31 Pedro Alves <[email protected]>
* pseudo-reloc.c (__text_start__): Declare.
(_pei386_runtime_relocator): On CE, don't reference
&__image_base__; get at the image base through __text_start__ -
0x1000 instead.
---
mingw/pseudo-reloc.c | 35 +++++++++++++++++++++++++++++------
1 file changed, 29 insertions(+), 6 deletions(-)
Index: mingw/pseudo-reloc.c
===================================================================
--- mingw.orig/pseudo-reloc.c 2009-12-31 18:52:36.000000000 +0000
+++ mingw/pseudo-reloc.c 2009-12-31 18:57:37.000000000 +0000
@@ -24,7 +24,8 @@
extern char __RUNTIME_PSEUDO_RELOC_LIST__;
extern char __RUNTIME_PSEUDO_RELOC_LIST_END__;
- extern char __U(_image_base__);
+ extern char __image_base__;
+ extern char __text_start__;
typedef struct {
DWORD addend;
@@ -165,17 +166,39 @@ do_pseudo_reloc (void * start, void * en
break;
#endif
}
- }
- }
-
+ }
+}
+
void
- _pei386_runtime_relocator ()
+ _pei386_runtime_relocator (void)
{
static int was_init = 0;
+#ifdef UNDER_CE
+ static volatile void *___image_base;
+ static volatile int ___pe_header_size;
+#endif
if (was_init)
return;
++was_init;
+
+#ifndef UNDER_CE
+ image_base = __image_base__;
+#else
+ /* The loader of Windows Mobile 6.1 and above refuses to apply base
+ relocations if the RVA falls out of the image. __image_base__
+ happens to be one such symbol, as most other ld magic symbols
+ (__dll__, __major_image_version__, etc. Basically, symbols that
+ end up on the absolute section. As an alternative to get at the
+ image base, we relocate against the __text_start__ symbol, and
+ subtract the PE header from that. In practice, this gives up the
+ image base. We go through volatile global to make sure gcc
+ doesn't fold the 0x1000 subtraction into the relocatable
+ address. */
+ ___image_base = &__text_start__;
+ ___pe_header_size = 0x1000;
+#endif
+
do_pseudo_reloc (&__RUNTIME_PSEUDO_RELOC_LIST__,
&__RUNTIME_PSEUDO_RELOC_LIST_END__,
- &__U(_image_base__));
+ (char *) ___image_base - ___pe_header_size);
}
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