x86, vdso: Patch alternatives in the 32-bit VDSO

We need the alternatives mechanism for rdtsc_barrier() to work.

Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-9-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/include/asm/vdso.h

@@ -28,4 +28,6 @@ extern const char vdso32_int80_start, vdso32_int80_end;
 extern const char vdso32_syscall_start, vdso32_syscall_end;
 extern const char vdso32_sysenter_start, vdso32_sysenter_end;
 
+void __init patch_vdso32(void *vdso, size_t len);
+
 #endif /* _ASM_X86_VDSO_H */

arch/x86/vdso/Makefile

@@ -21,7 +21,8 @@ vobjs-$(VDSOX32-y) += $(vobjx32s-compat)
 vobj64s := $(filter-out $(vobjx32s-compat),$(vobjs-y))
 
 # files to link into kernel
-obj-$(VDSO64-y)			+= vma.o vdso.o
+obj-y				+= vma.o
+obj-$(VDSO64-y)			+= vdso.o
 obj-$(VDSOX32-y)		+= vdsox32.o
 obj-$(VDSO32-y)			+= vdso32.o vdso32-setup.o
 

arch/x86/vdso/vdso32-setup.c

@@ -112,24 +112,25 @@ void enable_sep_cpu(void)
 
 int __init sysenter_setup(void)
 {
-	void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC);
-	const void *vsyscall;
-	size_t vsyscall_len;
+	void *vdso_page = (void *)get_zeroed_page(GFP_ATOMIC);
+	const void *vdso;
+	size_t vdso_len;
 
-	vdso32_pages[0] = virt_to_page(syscall_page);
+	vdso32_pages[0] = virt_to_page(vdso_page);
 
 	if (vdso32_syscall()) {
-		vsyscall = &vdso32_syscall_start;
-		vsyscall_len = &vdso32_syscall_end - &vdso32_syscall_start;
+		vdso = &vdso32_syscall_start;
+		vdso_len = &vdso32_syscall_end - &vdso32_syscall_start;
 	} else if (vdso32_sysenter()){
-		vsyscall = &vdso32_sysenter_start;
-		vsyscall_len = &vdso32_sysenter_end - &vdso32_sysenter_start;
+		vdso = &vdso32_sysenter_start;
+		vdso_len = &vdso32_sysenter_end - &vdso32_sysenter_start;
 	} else {
-		vsyscall = &vdso32_int80_start;
-		vsyscall_len = &vdso32_int80_end - &vdso32_int80_start;
+		vdso = &vdso32_int80_start;
+		vdso_len = &vdso32_int80_end - &vdso32_int80_start;
 	}
 
-	memcpy(syscall_page, vsyscall, vsyscall_len);
+	memcpy(vdso_page, vdso, vdso_len);
+	patch_vdso32(vdso_page, vdso_len);
 
 	return 0;
 }

arch/x86/vdso/vma.c

@@ -16,6 +16,7 @@
 #include <asm/vdso.h>
 #include <asm/page.h>
 
+#if defined(CONFIG_X86_64)
 unsigned int __read_mostly vdso_enabled = 1;
 
 extern char vdso_start[], vdso_end[];
@@ -28,8 +29,12 @@ static unsigned vdso_size;
 extern char vdsox32_start[], vdsox32_end[];
 extern struct page *vdsox32_pages[];
 static unsigned vdsox32_size;
+#endif
+#endif
 
-static void __init patch_vdsox32(void *vdso, size_t len)
+#if defined(CONFIG_X86_32) || defined(CONFIG_X86_X32_ABI) || \
+	defined(CONFIG_COMPAT)
+void __init patch_vdso32(void *vdso, size_t len)
 {
 	Elf32_Ehdr *hdr = vdso;
 	Elf32_Shdr *sechdrs, *alt_sec = 0;
@@ -52,7 +57,7 @@ static void __init patch_vdsox32(void *vdso, size_t len)
 	}
 
 	/* If we get here, it's probably a bug. */
-	pr_warning("patch_vdsox32: .altinstructions not found\n");
+	pr_warning("patch_vdso32: .altinstructions not found\n");
 	return;  /* nothing to patch */
 
 found:
@@ -61,6 +66,7 @@ found:
 }
 #endif
 
+#if defined(CONFIG_X86_64)
 static void __init patch_vdso64(void *vdso, size_t len)
 {
 	Elf64_Ehdr *hdr = vdso;
@@ -104,7 +110,7 @@ static int __init init_vdso(void)
 		vdso_pages[i] = virt_to_page(vdso_start + i*PAGE_SIZE);
 
 #ifdef CONFIG_X86_X32_ABI
-	patch_vdsox32(vdsox32_start, vdsox32_end - vdsox32_start);
+	patch_vdso32(vdsox32_start, vdsox32_end - vdsox32_start);
 	npages = (vdsox32_end - vdsox32_start + PAGE_SIZE - 1) / PAGE_SIZE;
 	vdsox32_size = npages << PAGE_SHIFT;
 	for (i = 0; i < npages; i++)
@@ -204,3 +210,4 @@ static __init int vdso_setup(char *s)
 	return 0;
 }
 __setup("vdso=", vdso_setup);
+#endif