From 5091e746848f74c9a2c0579b4ef8d8cd1a6b135d Mon Sep 17 00:00:00 2001 From: Ian Campbell Date: Mon, 25 Sep 2006 23:32:28 -0700 Subject: [PATCH] [PATCH] Translate asm version of ELFNOTE macro into preprocessor macro I've come across some problems with the assembly version of the ELFNOTE macro currently in -mm. (in x86-put-note-sections-into-a-pt_note-segment-in-vmlinux.patch) The first is that older gas does not support :varargs in .macro definitions (in my testing 2.17 does while 2.15 does not, I don't know when it became supported). The Changes file says binutils >= 2.12 so I think we need to avoid using it. There are no other uses in mainline or -mm. Old gas appears to just ignore it so you get "too many arguments" type errors. Secondly it seems that passing strings as arguments to assembler macros is broken without varargs. It looks like they get unquoted or each character is treated as a separate argument or something and this causes all manner of grief. I think this is because of the use of -traditional when compiling assembly files. Therefore I have translated the assembler macro into a pre-processor macro. I added the desctype as a separate argument instead of including it with the descdata as the previous version did since -traditional means the ELFNOTE definition after the #else needs to have the same number of arguments (I think so anyway, the -traditional CPP semantics are pretty fscking strange!). With this patch I am able to define elfnotes in assembly like this with both old and new assemblers. ELFNOTE(Xen, XEN_ELFNOTE_GUEST_OS, .asciz, "linux") ELFNOTE(Xen, XEN_ELFNOTE_GUEST_VERSION, .asciz, "2.6") ELFNOTE(Xen, XEN_ELFNOTE_XEN_VERSION, .asciz, "xen-3.0") ELFNOTE(Xen, XEN_ELFNOTE_VIRT_BASE, .long, __PAGE_OFFSET) Which seems reasonable enough. Signed-off-by: Ian Campbell Acked-by: Jeremy Fitzhardinge Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/elfnote.h | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-) diff --git a/include/linux/elfnote.h b/include/linux/elfnote.h index 16f9f8ebff..67396db141 100644 --- a/include/linux/elfnote.h +++ b/include/linux/elfnote.h @@ -31,22 +31,24 @@ /* * Generate a structure with the same shape as Elf{32,64}_Nhdr (which * turn out to be the same size and shape), followed by the name and - * desc data with appropriate padding. The 'desc' argument includes - * the assembler pseudo op defining the type of the data: .asciz - * "hello, world" + * desc data with appropriate padding. The 'desctype' argument is the + * assembler pseudo op defining the type of the data e.g. .asciz while + * 'descdata' is the data itself e.g. "hello, world". + * + * e.g. ELFNOTE(XYZCo, 42, .asciz, "forty-two") + * ELFNOTE(XYZCo, 12, .long, 0xdeadbeef) */ -.macro ELFNOTE name type desc:vararg -.pushsection ".note.\name" - .align 4 - .long 2f - 1f /* namesz */ - .long 4f - 3f /* descsz */ - .long \type -1:.asciz "\name" -2:.align 4 -3:\desc -4:.align 4 -.popsection -.endm +#define ELFNOTE(name, type, desctype, descdata) \ +.pushsection .note.name ; \ + .align 4 ; \ + .long 2f - 1f /* namesz */ ; \ + .long 4f - 3f /* descsz */ ; \ + .long type ; \ +1:.asciz "name" ; \ +2:.align 4 ; \ +3:desctype descdata ; \ +4:.align 4 ; \ +.popsection ; #else /* !__ASSEMBLER__ */ #include /* -- 2.39.5