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tile: implement gettimeofday() via vDSO

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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>
This commit is contained in:
Chris Metcalf
2013-08-07 15:33:32 -04:00
parent 0c1d1917c5
commit 4a556f4f56
22 changed files with 732 additions and 62 deletions
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5
arch/tile/kernel/stack.c
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@@ -29,6 +29,7 @@
#include <asm/switch_to.h>
#include <asm/sigframe.h>
#include <asm/stack.h>
#include <asm/vdso.h>
#include <arch/abi.h>
#include <arch/interrupts.h>
@@ -119,7 +120,7 @@ static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt)
/* Is the pc pointing to a sigreturn trampoline? */
static int is_sigreturn(unsigned long pc)
{
return (pc == VDSO_BASE);
return current->mm && (pc == VDSO_SYM(&__vdso_rt_sigreturn));
}
/* Return a pt_regs pointer for a valid signal handler frame */
@@ -128,7 +129,7 @@ static struct pt_regs *valid_sigframe(struct KBacktraceIterator* kbt,
{
BacktraceIterator *b = &kbt->it;
if (b->pc == VDSO_BASE && b->sp < PAGE_OFFSET &&
if (is_sigreturn(b->pc) && b->sp < PAGE_OFFSET &&
b->sp % sizeof(long) == 0) {
int retval;
pagefault_disable();