powerpc/vdso: Disable building the 32-bit VDSO on little endian

The only little endian configuration we support is ppc64le. As such if
we're building little endian we don't need a 32-bit VDSO, because there
is no 32-bit userspace.

This patch is a fairly ugly mess of #ifdefs, but is the minimal logic
required to disable the 32-bit VDSO. We can hopefully clean up the
result in future with some further refactoring.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index c1ebbdaac28fb85e37cb1fdf34c96e2e1175a977..87c7d1473488a95fc5956fa2f80bcef543b74b69 100644 (file)
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -33,11 +33,12 @@ obj-y                               := cputable.o ptrace.o syscalls.o \
                                   signal.o sysfs.o cacheinfo.o time.o \
                                   prom.o traps.o setup-common.o \
                                   udbg.o misc.o io.o dma.o \
-                                  misc_$(CONFIG_WORD_SIZE).o vdso32/ \
+                                  misc_$(CONFIG_WORD_SIZE).o \
                                   of_platform.o prom_parse.o
 obj-$(CONFIG_PPC64)            += setup_64.o sys_ppc32.o \
                                   signal_64.o ptrace32.o \
                                   paca.o nvram_64.o firmware.o
+obj-$(CONFIG_VDSO32)           += vdso32/
 obj-$(CONFIG_HAVE_HW_BREAKPOINT)       += hw_breakpoint.o
 obj-$(CONFIG_PPC_BOOK3S_64)    += cpu_setup_ppc970.o cpu_setup_pa6t.o
 obj-$(CONFIG_PPC_BOOK3S_64)    += cpu_setup_power.o

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 8331d0bef0fbc118052da0ff9f9085dfbb4c9386..b457bfa2843603f9c920236372effe6304da3bed 100644 (file)
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -49,13 +49,16 @@
 /* The alignment of the vDSO */
 #define VDSO_ALIGNMENT (1 << 16)
 
-extern char vdso32_start, vdso32_end;
-static void *vdso32_kbase = &vdso32_start;
 static unsigned int vdso32_pages;
+static void *vdso32_kbase;
 static struct page **vdso32_pagelist;
 unsigned long vdso32_sigtramp;
 unsigned long vdso32_rt_sigtramp;
 
+#ifdef CONFIG_VDSO32
+extern char vdso32_start, vdso32_end;
+#endif
+
 #ifdef CONFIG_PPC64
 extern char vdso64_start, vdso64_end;
 static void *vdso64_kbase = &vdso64_start;
@@ -248,6 +251,7 @@ const char *arch_vma_name(struct vm_area_struct *vma)
 
 
 
+#ifdef CONFIG_VDSO32
 static void * __init find_section32(Elf32_Ehdr *ehdr, const char *secname,
                                  unsigned long *size)
 {
@@ -335,6 +339,20 @@ static int __init vdso_do_func_patch32(struct lib32_elfinfo *v32,
 
        return 0;
 }
+#else /* !CONFIG_VDSO32 */
+static unsigned long __init find_function32(struct lib32_elfinfo *lib,
+                                           const char *symname)
+{
+       return 0;
+}
+
+static int __init vdso_do_func_patch32(struct lib32_elfinfo *v32,
+                                      struct lib64_elfinfo *v64,
+                                      const char *orig, const char *fix)
+{
+       return 0;
+}
+#endif /* CONFIG_VDSO32 */
 
 
 #ifdef CONFIG_PPC64
@@ -445,6 +463,7 @@ static __init int vdso_do_find_sections(struct lib32_elfinfo *v32,
         * Locate symbol tables & text section
         */
 
+#ifdef CONFIG_VDSO32
        v32->dynsym = find_section32(v32->hdr, ".dynsym", &v32->dynsymsize);
        v32->dynstr = find_section32(v32->hdr, ".dynstr", NULL);
        if (v32->dynsym == NULL || v32->dynstr == NULL) {
@@ -457,6 +476,7 @@ static __init int vdso_do_find_sections(struct lib32_elfinfo *v32,
                return -1;
        }
        v32->text = sect - vdso32_kbase;
+#endif
 
 #ifdef CONFIG_PPC64
        v64->dynsym = find_section64(v64->hdr, ".dynsym", &v64->dynsymsize);
@@ -493,7 +513,9 @@ static __init void vdso_setup_trampolines(struct lib32_elfinfo *v32,
 static __init int vdso_fixup_datapage(struct lib32_elfinfo *v32,
                                       struct lib64_elfinfo *v64)
 {
+#ifdef CONFIG_VDSO32
        Elf32_Sym *sym32;
+#endif
 #ifdef CONFIG_PPC64
        Elf64_Sym *sym64;
 
@@ -508,6 +530,7 @@ static __init int vdso_fixup_datapage(struct lib32_elfinfo *v32,
                (sym64->st_value - VDSO64_LBASE);
 #endif /* CONFIG_PPC64 */
 
+#ifdef CONFIG_VDSO32
        sym32 = find_symbol32(v32, "__kernel_datapage_offset");
        if (sym32 == NULL) {
                printk(KERN_ERR "vDSO32: Can't find symbol "
@@ -517,6 +540,7 @@ static __init int vdso_fixup_datapage(struct lib32_elfinfo *v32,
        *((int *)(vdso32_kbase + (sym32->st_value - VDSO32_LBASE))) =
                (vdso32_pages << PAGE_SHIFT) -
                (sym32->st_value - VDSO32_LBASE);
+#endif
 
        return 0;
 }
@@ -550,6 +574,7 @@ static __init int vdso_fixup_features(struct lib32_elfinfo *v32,
                                 start, start + size);
 #endif /* CONFIG_PPC64 */
 
+#ifdef CONFIG_VDSO32
        start = find_section32(v32->hdr, "__ftr_fixup", &size);
        if (start)
                do_feature_fixups(cur_cpu_spec->cpu_features,
@@ -571,6 +596,7 @@ static __init int vdso_fixup_features(struct lib32_elfinfo *v32,
        if (start)
                do_lwsync_fixups(cur_cpu_spec->cpu_features,
                                 start, start + size);
+#endif
 
        return 0;
 }
@@ -732,11 +758,15 @@ static int __init vdso_init(void)
 #endif /* CONFIG_PPC64 */
 
 
+#ifdef CONFIG_VDSO32
+       vdso32_kbase = &vdso32_start;
+
        /*
         * Calculate the size of the 32 bits vDSO
         */
        vdso32_pages = (&vdso32_end - &vdso32_start) >> PAGE_SHIFT;
        DBG("vdso32_kbase: %p, 0x%x pages\n", vdso32_kbase, vdso32_pages);
+#endif
 
 
        /*
@@ -757,6 +787,7 @@ static int __init vdso_init(void)
                return 0;
        }
 
+#ifdef CONFIG_VDSO32
        /* Make sure pages are in the correct state */
        vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 2),
                                  GFP_KERNEL);
@@ -769,6 +800,7 @@ static int __init vdso_init(void)
        }
        vdso32_pagelist[i++] = virt_to_page(vdso_data);
        vdso32_pagelist[i] = NULL;
+#endif
 
 #ifdef CONFIG_PPC64
        vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 2),

diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 7264e91190be928e125d01fe22be89a2b544c597..724ecc79140457c4b9e6d269499faceba334aa0f 100644 (file)
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -405,6 +405,16 @@ config PPC_DOORBELL
 
 endmenu
 
+config VDSO32
+       def_bool y
+       depends on PPC32 || CPU_BIG_ENDIAN
+       help
+         This symbol controls whether we build the 32-bit VDSO. We obviously
+         want to do that if we're building a 32-bit kernel. If we're building
+         a 64-bit kernel then we only want a 32-bit VDSO if we're building for
+         big endian. That is because the only little endian configuration we
+         support is ppc64le which is 64-bit only.
+
 choice
        prompt "Endianness selection"
        default CPU_BIG_ENDIAN