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>

include/asm-sh/auxvec.h

@@ -1,4 +1,18 @@
 #ifndef __ASM_SH_AUXVEC_H
 #define __ASM_SH_AUXVEC_H
 
+/*
+ * Architecture-neutral AT_ values in 0-17, leave some room
+ * for more of them.
+ */
+
+#ifdef CONFIG_VSYSCALL
+/*
+ * Only define this in the vsyscall case, the entry point to
+ * the vsyscall page gets placed here. The kernel will attempt
+ * to build a gate VMA we don't care about otherwise..
+ */
+#define AT_SYSINFO_EHDR		33
+#endif
+
 #endif /* __ASM_SH_AUXVEC_H */

include/asm-sh/elf.h

@@ -121,4 +121,24 @@ extern int dump_task_fpu (struct task_struct *, elf_fpregset_t *);
 #define ELF_CORE_COPY_FPREGS(tsk, elf_fpregs) dump_task_fpu(tsk, elf_fpregs)
 #endif
 
+#ifdef CONFIG_VSYSCALL
+/* vDSO has arch_setup_additional_pages */
+#define ARCH_HAS_SETUP_ADDITIONAL_PAGES
+struct linux_binprm;
+extern int arch_setup_additional_pages(struct linux_binprm *bprm,
+				       int executable_stack);
+
+extern unsigned int vdso_enabled;
+extern void __kernel_vsyscall;
+
+#define VDSO_BASE		((unsigned long)current->mm->context.vdso)
+#define VDSO_SYM(x)		(VDSO_BASE + (unsigned long)(x))
+
+#define ARCH_DLINFO						\
+do {								\
+	if (vdso_enabled)					\
+		NEW_AUX_ENT(AT_SYSINFO_EHDR, VDSO_BASE);	\
+} while (0)
+#endif /* CONFIG_VSYSCALL */
+
 #endif /* __ASM_SH_ELF_H */

include/asm-sh/mmu.h

@@ -11,7 +11,12 @@ typedef struct {
 #else
 
 /* Default "unsigned long" context */
-typedef unsigned long mm_context_t;
+typedef unsigned long mm_context_id_t;
+
+typedef struct {
+	mm_context_id_t id;
+	void *vdso;
+} mm_context_t;
 
 #endif /* CONFIG_MMU */
 

include/asm-sh/mmu_context.h

@@ -49,7 +49,7 @@ get_mmu_context(struct mm_struct *mm)
 	unsigned long mc = mmu_context_cache;
 
 	/* Check if we have old version of context. */
-	if (((mm->context ^ mc) & MMU_CONTEXT_VERSION_MASK) == 0)
+	if (((mm->context.id ^ mc) & MMU_CONTEXT_VERSION_MASK) == 0)
 		/* It's up to date, do nothing */
 		return;
 
@@ -68,7 +68,7 @@ get_mmu_context(struct mm_struct *mm)
 		if (!mc)
 			mmu_context_cache = mc = MMU_CONTEXT_FIRST_VERSION;
 	}
-	mm->context = mc;
+	mm->context.id = mc;
 }
 
 /*
@@ -78,7 +78,7 @@ get_mmu_context(struct mm_struct *mm)
 static __inline__ int init_new_context(struct task_struct *tsk,
 				       struct mm_struct *mm)
 {
-	mm->context = NO_CONTEXT;
+	mm->context.id = NO_CONTEXT;
 
 	return 0;
 }
@@ -123,7 +123,7 @@ static __inline__ unsigned long get_asid(void)
 static __inline__ void activate_context(struct mm_struct *mm)
 {
 	get_mmu_context(mm);
-	set_asid(mm->context & MMU_CONTEXT_ASID_MASK);
+	set_asid(mm->context.id & MMU_CONTEXT_ASID_MASK);
 }
 
 /* MMU_TTB can be used for optimizing the fault handling.

include/asm-sh/page.h

@@ -117,5 +117,10 @@ typedef struct { unsigned long pgprot; } pgprot_t;
 #include <asm-generic/memory_model.h>
 #include <asm-generic/page.h>
 
+/* vDSO support */
+#ifdef CONFIG_VSYSCALL
+#define __HAVE_ARCH_GATE_AREA
+#endif
+
 #endif /* __KERNEL__ */
 #endif /* __ASM_SH_PAGE_H */

include/asm-sh/processor.h

@@ -276,5 +276,11 @@ static inline void prefetch(void *x)
 #define prefetchw(x)	prefetch(x)
 #endif
 
+#ifdef CONFIG_VSYSCALL
+extern int vsyscall_init(void);
+#else
+#define vsyscall_init() do { } while (0)
+#endif
+
 #endif /* __KERNEL__ */
 #endif /* __ASM_SH_PROCESSOR_H */