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Diffstat (limited to 'arch/mips/kernel/vdso.c')
-rw-r--r--arch/mips/kernel/vdso.c38
1 files changed, 37 insertions, 1 deletions
diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
index 019035d7225c..48a9c6b90e07 100644
--- a/arch/mips/kernel/vdso.c
+++ b/arch/mips/kernel/vdso.c
@@ -13,13 +13,16 @@
#include <linux/err.h>
#include <linux/init.h>
#include <linux/ioport.h>
+#include <linux/kernel.h>
#include <linux/mm.h>
+#include <linux/random.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/timekeeper_internal.h>
#include <asm/abi.h>
#include <asm/mips-cps.h>
+#include <asm/page.h>
#include <asm/vdso.h>
/* Kernel-provided data used by the VDSO. */
@@ -95,6 +98,21 @@ void update_vsyscall_tz(void)
}
}
+static unsigned long vdso_base(void)
+{
+ unsigned long base;
+
+ /* Skip the delay slot emulation page */
+ base = STACK_TOP + PAGE_SIZE;
+
+ if (current->flags & PF_RANDOMIZE) {
+ base += get_random_int() & (VDSO_RANDOMIZE_SIZE - 1);
+ base = PAGE_ALIGN(base);
+ }
+
+ return base;
+}
+
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
struct mips_vdso_image *image = current->thread.abi->vdso;
@@ -128,12 +146,30 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
vvar_size = gic_size + PAGE_SIZE;
size = vvar_size + image->size;
- base = get_unmapped_area(NULL, 0, size, 0, 0);
+ /*
+ * Find a region that's large enough for us to perform the
+ * colour-matching alignment below.
+ */
+ if (cpu_has_dc_aliases)
+ size += shm_align_mask + 1;
+
+ base = get_unmapped_area(NULL, vdso_base(), size, 0, 0);
if (IS_ERR_VALUE(base)) {
ret = base;
goto out;
}
+ /*
+ * If we suffer from dcache aliasing, ensure that the VDSO data page
+ * mapping is coloured the same as the kernel's mapping of that memory.
+ * This ensures that when the kernel updates the VDSO data userland
+ * will observe it without requiring cache invalidations.
+ */
+ if (cpu_has_dc_aliases) {
+ base = __ALIGN_MASK(base, shm_align_mask);
+ base += ((unsigned long)&vdso_data - gic_size) & shm_align_mask;
+ }
+
data_addr = base + gic_size;
vdso_addr = data_addr + PAGE_SIZE;