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Commit 4a556f4f authored by Chris Metcalf's avatar Chris Metcalf
Browse files

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: default avatarChris Metcalf <cmetcalf@tilera.com>
parent 0c1d1917

arch/tile/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -64,6 +64,9 @@ config HUGETLB_SUPER_PAGES 
	depends on HUGETLB_PAGE && TILEGX

	def_bool y



config GENERIC_TIME_VSYSCALL

	def_bool y



# FIXME: tilegx can implement a more efficient rwsem.

config RWSEM_GENERIC_SPINLOCK

	def_bool y

arch/tile/include/asm/elf.h

+5 −0
Original line number Diff line number Diff line
@@ -132,6 +132,11 @@ extern int dump_task_regs(struct task_struct *, elf_gregset_t *); 
struct linux_binprm;

extern int arch_setup_additional_pages(struct linux_binprm *bprm,

				       int executable_stack);

#define ARCH_DLINFO \

do { \

	NEW_AUX_ENT(AT_SYSINFO_EHDR, VDSO_BASE); \

} while (0)



#ifdef CONFIG_COMPAT



#define COMPAT_ELF_PLATFORM "tilegx-m32"

arch/tile/include/asm/mmu.h

+1 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ struct mm_context { 
	 * semaphore but atomically, but it is conservatively set.

	 */

	unsigned long priority_cached;

	unsigned long vdso_base;

};



typedef struct mm_context mm_context_t;

arch/tile/include/asm/page.h

+7 −1
Original line number Diff line number Diff line
@@ -38,6 +38,12 @@ 
#define PAGE_MASK	(~(PAGE_SIZE - 1))

#define HPAGE_MASK	(~(HPAGE_SIZE - 1))



/*

 * We do define AT_SYSINFO_EHDR to support vDSO,

 * but don't use the gate mechanism.

 */

#define __HAVE_ARCH_GATE_AREA		1



/*

 * If the Kconfig doesn't specify, set a maximum zone order that

 * is enough so that we can create huge pages from small pages given
@@ -246,7 +252,7 @@ static inline __attribute_const__ int get_order(unsigned long size) 


#endif /* __tilegx__ */



#ifndef __ASSEMBLY__

#if !defined(__ASSEMBLY__) && !defined(VDSO_BUILD)



#ifdef CONFIG_HIGHMEM

arch/tile/include/asm/processor.h

+3 −3
Original line number Diff line number Diff line
@@ -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