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um: Fix overlapping ELF segments when statically linked

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When statically linked, the .text section in UML kernels is not page
aligned, causing it to share a page with the executable headers. As
.text and the executable headers have different permissions, this causes
the kernel to wish to map the same page twice (once as headers with r--
permissions, once as .text with r-x permissions), causing a segfault,
and a nasty message printed to the host kernel's dmesg:

"Uhuuh, elf segment at 0000000060000000 requested but the memory is
mapped already"

By aligning the .text to a page boundary (as in the dynamically linked
version in dyn.lds.S), there is no such overlap, and the kernel runs
correctly.

Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
David Gow 2020-03-05 10:39:39 -08:00 committed by Richard Weinberger
parent 73343392aa
commit 598f563036
1 changed files with 1 additions and 1 deletions
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2
arch/um/kernel/uml.lds.S
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@ -19,10 +19,10 @@ SECTIONS
__binary_start = START;
. = START + SIZEOF_HEADERS;
. = ALIGN(PAGE_SIZE);
_text = .;
INIT_TEXT_SECTION(0)
. = ALIGN(PAGE_SIZE);
.text :
{