sh: Initial vsyscall page support.

This implements initial support for the vsyscall page on SH.
At the moment we leave it configurable due to having nommu
to support from the same code base. We hook it up for the
signal trampoline return at present, with more to be added
later, once uClibc catches up.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

3 files changed, 26 insertions, 8 deletions

diff --git a/arch/sh/mm/Kconfig b/arch/sh/mm/Kconfig
index b445d02075e..9dd606464d2 100644
--- a/arch/sh/mm/Kconfig
+++ b/arch/sh/mm/Kconfig
@@ -223,6 +223,19 @@ config 32BIT
 	  32-bits through the SH-4A PMB. If this is not set, legacy
 	  29-bit physical addressing will be used.
 
+config VSYSCALL
+	bool "Support vsyscall page"
+	depends on MMU
+	default y
+	help
+	  This will enable support for the kernel mapping a vDSO page
+	  in process space, and subsequently handing down the entry point
+	  to the libc through the ELF auxiliary vector.
+
+	  From the kernel side this is used for the signal trampoline.
+	  For systems with an MMU that can afford to give up a page,
+	  (the default value) say Y.
+
 choice
 	prompt "HugeTLB page size"
 	depends on HUGETLB_PAGE && CPU_SH4 && MMU
diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
index ad182b31d84..7154d1ce978 100644
--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -286,6 +286,9 @@ void __init mem_init(void)
 		initsize >> 10);
 
 	p3_cache_init();
+
+	/* Initialize the vDSO */
+	vsyscall_init();
 }
 
 void free_initmem(void)
diff --git a/arch/sh/mm/tlb-flush.c b/arch/sh/mm/tlb-flush.c
index fd7e42bcaa4..73ec7f6084f 100644
--- a/arch/sh/mm/tlb-flush.c
+++ b/arch/sh/mm/tlb-flush.c
@@ -14,12 +14,12 @@
 
 void flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
 {
-	if (vma->vm_mm && vma->vm_mm->context != NO_CONTEXT) {
+	if (vma->vm_mm && vma->vm_mm->context.id != NO_CONTEXT) {
 		unsigned long flags;
 		unsigned long asid;
 		unsigned long saved_asid = MMU_NO_ASID;
 
-		asid = vma->vm_mm->context & MMU_CONTEXT_ASID_MASK;
+		asid = vma->vm_mm->context.id & MMU_CONTEXT_ASID_MASK;
 		page &= PAGE_MASK;
 
 		local_irq_save(flags);
@@ -39,20 +39,21 @@ void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 {
 	struct mm_struct *mm = vma->vm_mm;
 
-	if (mm->context != NO_CONTEXT) {
+	if (mm->context.id != NO_CONTEXT) {
 		unsigned long flags;
 		int size;
 
 		local_irq_save(flags);
 		size = (end - start + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
 		if (size > (MMU_NTLB_ENTRIES/4)) { /* Too many TLB to flush */
-			mm->context = NO_CONTEXT;
+			mm->context.id = NO_CONTEXT;
 			if (mm == current->mm)
 				activate_context(mm);
 		} else {
-			unsigned long asid = mm->context&MMU_CONTEXT_ASID_MASK;
+			unsigned long asid;
 			unsigned long saved_asid = MMU_NO_ASID;
 
+			asid = mm->context.id & MMU_CONTEXT_ASID_MASK;
 			start &= PAGE_MASK;
 			end += (PAGE_SIZE - 1);
 			end &= PAGE_MASK;
@@ -81,9 +82,10 @@ void flush_tlb_kernel_range(unsigned long start, unsigned long end)
 	if (size > (MMU_NTLB_ENTRIES/4)) { /* Too many TLB to flush */
 		flush_tlb_all();
 	} else {
-		unsigned long asid = init_mm.context&MMU_CONTEXT_ASID_MASK;
+		unsigned long asid;
 		unsigned long saved_asid = get_asid();
 
+		asid = init_mm.context.id & MMU_CONTEXT_ASID_MASK;
 		start &= PAGE_MASK;
 		end += (PAGE_SIZE - 1);
 		end &= PAGE_MASK;
@@ -101,11 +103,11 @@ void flush_tlb_mm(struct mm_struct *mm)
 {
 	/* Invalidate all TLB of this process. */
 	/* Instead of invalidating each TLB, we get new MMU context. */
-	if (mm->context != NO_CONTEXT) {
+	if (mm->context.id != NO_CONTEXT) {
 		unsigned long flags;
 
 		local_irq_save(flags);
-		mm->context = NO_CONTEXT;
+		mm->context.id = NO_CONTEXT;
 		if (mm == current->mm)
 			activate_context(mm);
 		local_irq_restore(flags);