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authorRoland McGrath <roland@redhat.com>2005-04-16 15:24:48 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:24:48 -0700
commitc97db4a0a7d4d5be8c64a8d649a4425ee195b05c (patch)
treee310d0f9918d7a47359872fa519e2abe10b5d522
parentecd02dddd1d5bfc2141cbd0e205a53fb9d849c9e (diff)
[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 <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/i386/kernel/Makefile6
-rw-r--r--arch/i386/kernel/vsyscall-note.S25
-rw-r--r--arch/i386/kernel/vsyscall.lds.S3
3 files changed, 31 insertions, 3 deletions
diff --git a/arch/i386/kernel/Makefile b/arch/i386/kernel/Makefile
index 933787a46b4..aacdae6f372 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 00000000000..d4b5be4f3d5
--- /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 <linux/uts.h>
+#include <linux/version.h>
+
+#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 3a8329d6536..a7977707c8e 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 */
}