- Use runtime pagesize (Jeremy Kerr)

Some powerpc machines can support 64k pages, enabled by the
CONFIG_64K_PAGES option in linux.

However, the uClibc dynamic loader won't currently work on these
machines, as it uses hard-coded values (PAGE_ALIGN, ADDR_ALIGN and
OFFS_ALIGN) in the ldso architecture-specific headers.  When running on
a kernel with 64k pages, ld.so tries to mmap with 4k-aligned addresses,
rather than 64k, so mmap fails with -EINVAL.

When booting a 64k machine with a uClibc dynamic linker, init fails
with:

/init:500: can't map '/lib/libc.so.0'
/init:500: can't map '/lib/libc.so.0'
/init:500: can't map '/lib/libc.so.0'
/init: can't load library 'libc.so.0'
Kernel panic - not syncing: Attempted to kill init!

This change allows ld.so determine these alignment masks at runtime,
rather than compile-time. Since we have the _dl_pagesize variable
available, we can use that to generate the appropriate masks.

Since almost all of the architectures can use the common definitions for
the _ALIGN macros, we can consolidate them all in ldso.h, and override
in the sysdep headers where necessary (ie, mips).

This allows me to start a uClibc-based root fs on a 64k machine.

Signed-off-by: Jeremy Kerr <jk at ozlabs org>

1 files changed, 0 insertions, 6 deletions

diff --git a/ldso/ldso/bfin/dl-sysdep.h b/ldso/ldso/bfin/dl-sysdep.h
index 52df4c91f..a3563a0de 100644
--- a/ldso/ldso/bfin/dl-sysdep.h
+++ b/ldso/ldso/bfin/dl-sysdep.h
@@ -67,12 +67,6 @@ struct funcdesc_value
 
 extern int _dl_linux_resolve(void) __attribute__((__visibility__("hidden")));
 
-/* 4KiB page alignment.  Should perhaps be made dynamic using
-   getpagesize(), based on AT_PAGESZ from auxvt?  */
-#define PAGE_ALIGN 0xfffff000
-#define ADDR_ALIGN 0xfff
-#define OFFS_ALIGN 0x7ffff000
-
 struct funcdesc_ht;
 
 #undef SEND_EARLY_STDERR