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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
commit 4a556f4f56
22 changed files with 732 additions and 62 deletions
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6
arch/tile/include/asm/processor.h
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@ -180,10 +180,10 @@ struct thread_struct {
#define TASK_SIZE TASK_SIZE_MAX
#endif
/* We provide a minimal "vdso" a la x86; just the sigreturn code for now. */
#define VDSO_BASE (TASK_SIZE - PAGE_SIZE)
#define VDSO_BASE ((unsigned long)current->active_mm->context.vdso_base)
#define VDSO_SYM(x) (VDSO_BASE + (unsigned long)(x))
#define STACK_TOP VDSO_BASE
#define STACK_TOP TASK_SIZE
/* STACK_TOP_MAX is used temporarily in execve and should not check COMPAT. */
#define STACK_TOP_MAX TASK_SIZE_MAX