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[patch] Fix PIE for 64bit gdb -> 32bit inferior
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- To: gdb-patches at sourceware dot org
- Cc: Mark Kettenis <mark dot kettenis at xs4all dot nl>
- Date: Thu, 11 Feb 2010 16:06:57 +0100
- Subject: [patch] Fix PIE for 64bit gdb -> 32bit inferior
Hi,
according to the suggestion by Mark Kettenis the fix for biarch PIE is in fact
simple.
The displacement for cross-arch inferiors can use 64bit math operations if its
bits 32..63 are properly set to either 0x00000000 << 32 or 0xffffffff << 32 as
appropriate.
No regressions on {x86_64,x86_64-m32,i686}-fedora12-linux-gnu. It fixes some
FAILs of gdb.base/break-interp.exp on {x86_64-m32}-fedora12-linux-gnu
(therefore host=x86_64-fedora12-linux-gnu target=i686-fedora12-linux-gnu).
Thanks,
Jan
2010-02-11 Jan Kratochvil <jan.kratochvil@redhat.com>
* solib-svr4.c (enable_break <target_auxv_search>): New variable
addr_bit. Adjust LOAD_ADDR sign for cross-arch inferiors.
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -1428,7 +1428,32 @@ enable_break (struct svr4_info *info, int from_tty)
from our so_list, then try using the AT_BASE auxilliary entry. */
if (!load_addr_found)
if (target_auxv_search (¤t_target, AT_BASE, &load_addr) > 0)
- load_addr_found = 1;
+ {
+ int addr_bit = gdbarch_addr_bit (target_gdbarch);
+
+ /* Ensure LOAD_ADDR has proper sign in its possible upper bits so
+ that `+ load_addr' will overflow CORE_ADDR width not creating
+ invalid addresses like 0x101234567 for 32bit inferiors on 64bit
+ GDB. */
+
+ if (addr_bit < (sizeof (ULONGEST) * HOST_CHAR_BIT))
+ {
+ CORE_ADDR space_size = (ULONGEST) 1 << addr_bit;
+ CORE_ADDR tmp_entry_point = exec_entry_point (tmp_bfd,
+ tmp_bfd_target);
+
+ gdb_assert (load_addr < space_size);
+
+ /* TMP_ENTRY_POINT exceeding SPACE_SIZE would be for prelinked
+ 64bit ld.so with 32bit executable, it should not happen. */
+
+ if (tmp_entry_point < space_size
+ && tmp_entry_point + load_addr >= space_size)
+ load_addr -= space_size;
+ }
+
+ load_addr_found = 1;
+ }
/* Otherwise we find the dynamic linker's base address by examining
the current pc (which should point at the entry point for the