The patch titled
Subject: powerpc/vdso: refactor error handling
has been added to the -mm mm-unstable branch. Its filename is
powerpc-vdso-refactor-error-handling.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/powerpc-vdso-refactor-error-handling.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Subject: powerpc/vdso: refactor error handling
Date: Mon, 12 Aug 2024 18:26:05 +1000
Linus noticed that the error handling in __arch_setup_additional_pages()
fails to clear the mm VDSO pointer if _install_special_mapping() fails.
In practice there should be no actual bug, because if there's an error the
VDSO pointer is cleared later in arch_setup_additional_pages().
However it's no longer necessary to set the pointer before installing the
mapping. Commit c1bab64360e6 ("powerpc/vdso: Move to
_install_special_mapping() and remove arch_vma_name()") reworked the code
so that the VMA name comes from the vm_special_mapping.name, rather than
relying on arch_vma_name().
So rework the code to only set the VDSO pointer once the mappings have
been installed correctly, and remove the stale comment.
Link: https://lkml.kernel.org/r/20240812082605.743814-4-mpe@xxxxxxxxxxxxxx
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Jeff Xu <jeffxu@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Pedro Falcato <pedro.falcato@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kernel/vdso.c | 18 +++++++-----------
1 file changed, 7 insertions(+), 11 deletions(-)
--- a/arch/powerpc/kernel/vdso.c~powerpc-vdso-refactor-error-handling
+++ a/arch/powerpc/kernel/vdso.c
@@ -214,13 +214,6 @@ static int __arch_setup_additional_pages
/* Add required alignment. */
vdso_base = ALIGN(vdso_base, VDSO_ALIGNMENT);
- /*
- * Put vDSO base into mm struct. We need to do this before calling
- * install_special_mapping or the perf counter mmap tracking code
- * will fail to recognise it as a vDSO.
- */
- mm->context.vdso = (void __user *)vdso_base + vvar_size;
-
vma = _install_special_mapping(mm, vdso_base, vvar_size,
VM_READ | VM_MAYREAD | VM_IO |
VM_DONTDUMP | VM_PFNMAP, &vvar_spec);
@@ -240,10 +233,15 @@ static int __arch_setup_additional_pages
vma = _install_special_mapping(mm, vdso_base + vvar_size, vdso_size,
VM_READ | VM_EXEC | VM_MAYREAD |
VM_MAYWRITE | VM_MAYEXEC, vdso_spec);
- if (IS_ERR(vma))
+ if (IS_ERR(vma)) {
do_munmap(mm, vdso_base, vvar_size, NULL);
+ return PTR_ERR(vma);
+ }
+
+ // Now that the mappings are in place, set the mm VDSO pointer
+ mm->context.vdso = (void __user *)vdso_base + vvar_size;
- return PTR_ERR_OR_ZERO(vma);
+ return 0;
}
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
@@ -257,8 +255,6 @@ int arch_setup_additional_pages(struct l
return -EINTR;
rc = __arch_setup_additional_pages(bprm, uses_interp);
- if (rc)
- mm->context.vdso = NULL;
mmap_write_unlock(mm);
return rc;
_
Patches currently in -mm which might be from mpe@xxxxxxxxxxxxxx are
mm-add-optional-close-to-struct-vm_special_mapping.patch
powerpc-mm-handle-vdso-unmapping-via-close-rather-than-arch_unmap.patch
mm-remove-arch_unmap.patch
powerpc-vdso-refactor-error-handling.patch
