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Message-ID: <20240807124103.85644-2-mpe@ellerman.id.au>
Date: Wed, 7 Aug 2024 22:41:01 +1000
From: Michael Ellerman <mpe@...erman.id.au>
To: <linux-mm@...ck.org>
Cc: <linuxppc-dev@...ts.ozlabs.org>,
torvalds@...ux-foundation.org,
akpm@...ux-foundation.org,
christophe.leroy@...roup.eu,
jeffxu@...omium.org,
jeffxu@...gle.com,
Liam.Howlett@...cle.com,
linux-kernel@...r.kernel.org,
npiggin@...il.com,
oliver.sang@...el.com,
pedro.falcato@...il.com
Subject: [PATCH 2/4] powerpc/mm: Handle VDSO unmapping via close() rather than arch_unmap()
Add a close() callback to the VDSO special mapping to handle unmapping
of the VDSO. That will make it possible to remove the arch_unmap() hook
entirely in a subsequent patch.
Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
---
arch/powerpc/include/asm/mmu_context.h | 4 ----
arch/powerpc/kernel/vdso.c | 17 +++++++++++++++++
2 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index 37bffa0f7918..9b8c1555744e 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -263,10 +263,6 @@ extern void arch_exit_mmap(struct mm_struct *mm);
static inline void arch_unmap(struct mm_struct *mm,
unsigned long start, unsigned long end)
{
- unsigned long vdso_base = (unsigned long)mm->context.vdso;
-
- if (start <= vdso_base && vdso_base < end)
- mm->context.vdso = NULL;
}
#ifdef CONFIG_PPC_MEM_KEYS
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 7a2ff9010f17..220a76cae7c1 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -81,6 +81,21 @@ static int vdso64_mremap(const struct vm_special_mapping *sm, struct vm_area_str
return vdso_mremap(sm, new_vma, &vdso64_end - &vdso64_start);
}
+static void vdso_close(const struct vm_special_mapping *sm, struct vm_area_struct *vma)
+{
+ struct mm_struct *mm = vma->vm_mm;
+
+ /*
+ * close() is called for munmap() but also for mremap(). In the mremap()
+ * case the vdso pointer has already been updated by the mremap() hook
+ * above, so it must not be set to NULL here.
+ */
+ if (vma->vm_start != (unsigned long)mm->context.vdso)
+ return;
+
+ mm->context.vdso = NULL;
+}
+
static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
struct vm_area_struct *vma, struct vm_fault *vmf);
@@ -92,11 +107,13 @@ static struct vm_special_mapping vvar_spec __ro_after_init = {
static struct vm_special_mapping vdso32_spec __ro_after_init = {
.name = "[vdso]",
.mremap = vdso32_mremap,
+ .close = vdso_close,
};
static struct vm_special_mapping vdso64_spec __ro_after_init = {
.name = "[vdso]",
.mremap = vdso64_mremap,
+ .close = vdso_close,
};
#ifdef CONFIG_TIME_NS
--
2.45.2
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