Re: elf: add livepatch-specific elf constants

+++ Josh Poimboeuf [12/11/15 09:45 -0600]:

On Mon, Nov 09, 2015 at 11:45:51PM -0500, Jessica Yu wrote:

quoted

Add livepatch elf reloc section flag, livepatch symbol bind
and section index

Signed-off-by: Jessica Yu <redacted>
---
 include/uapi/linux/elf.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
index 71e1d0e..967ce1b 100644
--- a/include/uapi/linux/elf.h
+++ b/include/uapi/linux/elf.h

@@ -118,6 +118,7 @@ typedef __s64	Elf64_Sxword;
 #define STB_LOCAL  0
 #define STB_GLOBAL 1
 #define STB_WEAK   2
+#define STB_LIVEPATCH_EXT 11

 #define STT_NOTYPE  0
 #define STT_OBJECT  1

@@ -286,6 +287,7 @@ typedef struct elf64_phdr {
 #define SHF_ALLOC	0x2
 #define SHF_EXECINSTR	0x4
 #define SHF_MASKPROC	0xf0000000
+#define SHF_RELA_LIVEPATCH  0x4000000

Writing the value with leading zeros (0x04000000) would it more
readable.

Also the OS-specific range mask (SHF_MASKOS) is 0x0ff00000.  Any reason
you went with 0x04000000 as opposed to the first value in the range
(0x00100000)?  I don't see anybody else using that value.

I don't have any particular reason, I think I just picked any value
and ran with it. I'll just change it to the first value in the range
since that makes more sense.

quoted

 /* special section indexes */
 #define SHN_UNDEF	0

@@ -295,6 +297,7 @@ typedef struct elf64_phdr {
 #define SHN_ABS		0xfff1
 #define SHN_COMMON	0xfff2
 #define SHN_HIRESERVE	0xffff
+#define SHN_LIVEPATCH 0xff21

Similar question here, why not use 0xff20 (SHN_LOOS)?

-- 
Josh