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authorDmitry Safonov <dsafonov@virtuozzo.com>2017-07-26 20:07:37 +0300
committerCatalin Marinas <catalin.marinas@arm.com>2017-08-09 12:16:28 +0100
commit739586951b8abe381a98797a5e27a0a9336333d6 (patch)
treec169ef82d580fe74b081bdae45fbc49a2b668d50 /arch/arm64/kernel
parentarm64: uaccess: Implement *_flushcache variants (diff)
downloadlinux-dev-739586951b8abe381a98797a5e27a0a9336333d6.tar.xz
linux-dev-739586951b8abe381a98797a5e27a0a9336333d6.zip
arm64/vdso: Support mremap() for vDSO
vDSO VMA address is saved in mm_context for the purpose of using restorer from vDSO page to return to userspace after signal handling. In Checkpoint Restore in Userspace (CRIU) project we place vDSO VMA on restore back to the place where it was on the dump. With the exception for x86 (where there is API to map vDSO with arch_prctl()), we move vDSO inherited from CRIU task to restoree position by mremap(). CRIU does support arm64 architecture, but kernel doesn't update context.vdso pointer after mremap(). Which results in translation fault after signal handling on restored application: https://github.com/xemul/criu/issues/288 Make vDSO code track the VMA address by supplying .mremap() fops the same way it's done for x86 and arm32 by: commit b059a453b1cf ("x86/vdso: Add mremap hook to vm_special_mapping") commit 280e87e98c09 ("ARM: 8683/1: ARM32: Support mremap() for sigpage/vDSO"). Cc: Russell King <rmk+kernel@armlinux.org.uk> Cc: linux-arm-kernel@lists.infradead.org Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Pavel Emelyanov <xemul@virtuozzo.com> Cc: Christopher Covington <cov@codeaurora.org> Reviewed-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel')
-rw-r--r--arch/arm64/kernel/vdso.c15
1 files changed, 15 insertions, 0 deletions
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index e8f759f764f2..2d419006ad43 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -110,12 +110,27 @@ int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
}
#endif /* CONFIG_COMPAT */
+static int vdso_mremap(const struct vm_special_mapping *sm,
+ struct vm_area_struct *new_vma)
+{
+ unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
+ unsigned long vdso_size = vdso_end - vdso_start;
+
+ if (vdso_size != new_size)
+ return -EINVAL;
+
+ current->mm->context.vdso = (void *)new_vma->vm_start;
+
+ return 0;
+}
+
static struct vm_special_mapping vdso_spec[2] __ro_after_init = {
{
.name = "[vvar]",
},
{
.name = "[vdso]",
+ .mremap = vdso_mremap,
},
};