From c97db4a0a7d4d5be8c64a8d649a4425ee195b05c Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Sat, 16 Apr 2005 15:24:48 -0700 Subject: [PATCH] [PATCH] i386 vDSO: add PT_NOTE segment This patch adds an ELF note to the vDSO giving the LINUX_VERSION_CODE value. Having this in the vDSO lets the dynamic linker avoid the `uname' syscall it now always does at startup to ascertain the kernel ABI available. Signed-off-by: Roland McGrath Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/kernel/Makefile | 6 ++++-- arch/i386/kernel/vsyscall-note.S | 25 +++++++++++++++++++++++++ arch/i386/kernel/vsyscall.lds.S | 3 ++- 3 files changed, 31 insertions(+), 3 deletions(-) create mode 100644 arch/i386/kernel/vsyscall-note.S diff --git a/arch/i386/kernel/Makefile b/arch/i386/kernel/Makefile index 933787a46b..aacdae6f37 100644 --- a/arch/i386/kernel/Makefile +++ b/arch/i386/kernel/Makefile @@ -56,7 +56,8 @@ SYSCFLAGS_vsyscall-sysenter.so = $(vsyscall-flags) SYSCFLAGS_vsyscall-int80.so = $(vsyscall-flags) $(obj)/vsyscall-int80.so $(obj)/vsyscall-sysenter.so: \ -$(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE +$(obj)/vsyscall-%.so: $(src)/vsyscall.lds \ + $(obj)/vsyscall-%.o $(obj)/vsyscall-note.o FORCE $(call if_changed,syscall) # We also create a special relocatable object that should mirror the symbol @@ -67,5 +68,6 @@ $(obj)/built-in.o: $(obj)/vsyscall-syms.o $(obj)/built-in.o: ld_flags += -R $(obj)/vsyscall-syms.o SYSCFLAGS_vsyscall-syms.o = -r -$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds $(obj)/vsyscall-sysenter.o FORCE +$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds \ + $(obj)/vsyscall-sysenter.o $(obj)/vsyscall-note.o FORCE $(call if_changed,syscall) diff --git a/arch/i386/kernel/vsyscall-note.S b/arch/i386/kernel/vsyscall-note.S new file mode 100644 index 0000000000..d4b5be4f3d --- /dev/null +++ b/arch/i386/kernel/vsyscall-note.S @@ -0,0 +1,25 @@ +/* + * This supplies .note.* sections to go into the PT_NOTE inside the vDSO text. + * Here we can supply some information useful to userland. + */ + +#include +#include + +#define ASM_ELF_NOTE_BEGIN(name, flags, vendor, type) \ + .section name, flags; \ + .balign 4; \ + .long 1f - 0f; /* name length */ \ + .long 3f - 2f; /* data length */ \ + .long type; /* note type */ \ +0: .asciz vendor; /* vendor name */ \ +1: .balign 4; \ +2: + +#define ASM_ELF_NOTE_END \ +3: .balign 4; /* pad out section */ \ + .previous + + ASM_ELF_NOTE_BEGIN(".note.kernel-version", "a", UTS_SYSNAME, 0) + .long LINUX_VERSION_CODE + ASM_ELF_NOTE_END diff --git a/arch/i386/kernel/vsyscall.lds.S b/arch/i386/kernel/vsyscall.lds.S index 3a8329d653..a7977707c8 100644 --- a/arch/i386/kernel/vsyscall.lds.S +++ b/arch/i386/kernel/vsyscall.lds.S @@ -23,7 +23,7 @@ SECTIONS . = VSYSCALL_BASE + 0x400; .text : { *(.text) } :text =0x90909090 - + .note : { *(.note.*) } :text :note .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr .eh_frame : { KEEP (*(.eh_frame)) } :text .dynamic : { *(.dynamic) } :text :dynamic @@ -43,6 +43,7 @@ PHDRS { text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */ dynamic PT_DYNAMIC FLAGS(4); /* PF_R */ + note PT_NOTE FLAGS(4); /* PF_R */ eh_frame_hdr 0x6474e550; /* PT_GNU_EH_FRAME, but ld doesn't match the name */ } -- 2.39.5