[Xen-devel] [PATCH v7 02/14] x86: properly calculate xen ELF end of image address

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

Currently xen ELF end of image address is calculated using first line from
"nm -nr xen/xen-syms" output. However, sometimes it may contain random
symbol address not related to the end of image in any way. It can happen
if a symbol is introduced with address larger than __end_of_image__ symbol
address. Such situation encountered when I linked xen ELF binary with
xen/arch/x86/efi/relocs-dummy.S. Then first line from "nm -nr xen/xen-syms"
contained "ffff82d0c0000000 A ALT_START" and xen ELF image memory size
was silently set to 1023 MiB. This issue happened because there is no
check which symbol address is used to calculate end of image address. So,
let's fix it and take ELF end of image address by reading __end_of_image__
symbol address from nm output. This way xen ELF image build process is
not prone to changes in order of nm output.

Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
---
v7 - suggestions/fixes:
   - use sed instead of awk
     (suggested by Jan Beulich),
   - improve commit message
     (suggested by Jan Beulich).
---
 xen/arch/x86/Makefile |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index d3875c5..c3a8920 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -91,7 +91,7 @@ endif
 
 $(TARGET): $(TARGET)-syms $(efi-y) boot/mkelf32
        ./boot/mkelf32 $(notes_phdrs) $(TARGET)-syms $(TARGET) 0x100000 \
-       `$(NM) -nr $(TARGET)-syms | head -n 1 | sed -e 's/^\([^ ]*\).*/0x\1/'`
+               `$(NM) $(TARGET)-syms | sed -ne 's/^\([^ ]*\) . 
__end_of_image__$$/0x\1/p'`
 
 .PHONY: tests
 tests:
-- 
1.7.10.4


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