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target-ppc: Confirm That .bss Pages Are Valid 

The existing code does a check to ensure that a .bss region is properly
mmap'd.  When additional mmap is required, the (guest) pages are also
validated.  However, this code has a bug: when host page size is larger
than target page size, it is possible for the .bss pages to already be
(host) mapped but the guest .bss pages may not be valid.

The check to mmap additional space is separated from the flagging of the
target (guest) pages, thus ensuring that both aspects are done properly.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Tom Musta 2014-05-29 09:12:23 -05:00 committed by Alexander Graf
parent 5b274ed74d
commit f46e9a0b99
1 changed files with 4 additions and 3 deletions
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7
linux-user/elfload.c
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@ -1425,10 +1425,11 @@ static void zero_bss(abi_ulong elf_bss, abi_ulong last_bss, int prot)
perror("cannot mmap brk");
exit(-1);
}
}
/* Since we didn't use target_mmap, make sure to record
the validity of the pages with qemu. */
page_set_flags(elf_bss & TARGET_PAGE_MASK, last_bss, prot|PAGE_VALID);
/* Ensure that the bss page(s) are valid */
if ((page_get_flags(last_bss-1) & prot) != prot) {
page_set_flags(elf_bss & TARGET_PAGE_MASK, last_bss, prot | PAGE_VALID);
}
if (host_start < host_map_start) {