tile: implement gettimeofday() via vDSO

This change creates the framework for vDSO calls, makes the existing
rt_sigreturn() mechanism use it, and adds a fast gettimeofday().
Now that we need to expose the vDSO address to userspace, we add
AT_SYSINFO_EHDR to the set of aux entries provided to userspace.
(You can disable any extra vDSO support by booting with vdso=0,
but the rt_sigreturn vDSO page will still be provided.)

Note that glibc has supported the tile vDSO since release 2.17.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

1 files changed, 0 insertions, 16 deletions

diff --git a/arch/tile/kernel/entry.S b/arch/tile/kernel/entry.S
index f116cb0bce20..3d9175992a20 100644
--- a/arch/tile/kernel/entry.S
+++ b/arch/tile/kernel/entry.S
@@ -27,22 +27,6 @@ STD_ENTRY(current_text_addr)
         { move r0, lr; jrp lr }
         STD_ENDPROC(current_text_addr)
 
-/*
- * We don't run this function directly, but instead copy it to a page
- * we map into every user process.  See vdso_setup().
- *
- * Note that libc has a copy of this function that it uses to compare
- * against the PC when a stack backtrace ends, so if this code is
- * changed, the libc implementation(s) should also be updated.
- */
-        .pushsection .data
-ENTRY(__rt_sigreturn)
-        moveli TREG_SYSCALL_NR_NAME,__NR_rt_sigreturn
-        swint1
-        ENDPROC(__rt_sigreturn)
-        ENTRY(__rt_sigreturn_end)
-        .popsection
-
 STD_ENTRY(dump_stack)
         { move r2, lr; lnk r1 }
         { move r4, r52; addli r1, r1, dump_stack - . }