[PATCH 2/4] powerpc/mm: Handle VDSO unmapping via close() rather than arch_unmap()
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2024-08-07 12:41:18
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
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@linux-foundation.org> Signed-off-by: Michael Ellerman <mpe@ellerman.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
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2.45.2