Subject: Re: [PATCH 2/3] mm: Pass vm_flags to generic_get_unmapped_area()

From: Michael Ellerman <[email-masked]>
Date: Wed, 04 Sep 2024 14:13:47 +1000

Mark Brown <[email-masked]> writes:
> In preparation for using vm_flags to ensure guard pages for shadow stacks
> supply them as an argument to generic_get_unmapped_area(). The only user
> outside of the core code is the PowerPC book3s64 implementation which is
> trivially wrapping the generic implementation in the radix_enabled() case.
>
> Signed-off-by: Mark Brown <[email-masked]>
> ---
>  arch/powerpc/mm/book3s64/slice.c |  4 ++--
>  include/linux/sched/mm.h         |  4 ++--
>  mm/mmap.c                        | 10 ++++++----
>  3 files changed, 10 insertions(+), 8 deletions(-)

Acked-by: Michael Ellerman <[email-masked]> (powerpc)

cheers

> diff --git a/arch/powerpc/mm/book3s64/slice.c b/arch/powerpc/mm/book3s64/slice.c
> index ada6bf896ef8..87307d0fc3b8 100644
> --- a/arch/powerpc/mm/book3s64/slice.c
> +++ b/arch/powerpc/mm/book3s64/slice.c
> @@ -641,7 +641,7 @@ unsigned long arch_get_unmapped_area(struct file *filp,
>  				     vm_flags_t vm_flags)
>  {
>  	if (radix_enabled())
> -		return generic_get_unmapped_area(filp, addr, len, pgoff, flags);
> +		return generic_get_unmapped_area(filp, addr, len, pgoff, flags, vm_flags);
>  
>  	return slice_get_unmapped_area(addr, len, flags,
>  				       mm_ctx_user_psize(&current->mm->context), 0);
> @@ -655,7 +655,7 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp,
>  					     vm_flags_t vm_flags)
>  {
>  	if (radix_enabled())
> -		return generic_get_unmapped_area_topdown(filp, addr0, len, pgoff, flags);
> +		return generic_get_unmapped_area_topdown(filp, addr0, len, pgoff, flags, vm_flags);
>  
>  	return slice_get_unmapped_area(addr0, len, flags,
>  				       mm_ctx_user_psize(&current->mm->context), 1);
> diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
> index c4d34abc45d4..07bb8d4181d7 100644
> --- a/include/linux/sched/mm.h
> +++ b/include/linux/sched/mm.h
> @@ -204,11 +204,11 @@ unsigned long mm_get_unmapped_area_vmflags(struct mm_struct *mm,
>  unsigned long
>  generic_get_unmapped_area(struct file *filp, unsigned long addr,
>  			  unsigned long len, unsigned long pgoff,
> -			  unsigned long flags);
> +			  unsigned long flags, vm_flags_t vm_flags);
>  unsigned long
>  generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
>  				  unsigned long len, unsigned long pgoff,
> -				  unsigned long flags);
> +				  unsigned long flags, vm_flags_t vm_flags);
>  #else
>  static inline void arch_pick_mmap_layout(struct mm_struct *mm,
>  					 struct rlimit *rlim_stack) {}
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 7528146f886f..b06ba847c96e 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1789,7 +1789,7 @@ unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
>  unsigned long
>  generic_get_unmapped_area(struct file *filp, unsigned long addr,
>  			  unsigned long len, unsigned long pgoff,
> -			  unsigned long flags)
> +			  unsigned long flags, vm_flags_t vm_flags)
>  {
>  	struct mm_struct *mm = current->mm;
>  	struct vm_area_struct *vma, *prev;
> @@ -1823,7 +1823,8 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
>  		       unsigned long len, unsigned long pgoff,
>  		       unsigned long flags, vm_flags_t vm_flags)
>  {
> -	return generic_get_unmapped_area(filp, addr, len, pgoff, flags);
> +	return generic_get_unmapped_area(filp, addr, len, pgoff, flags,
> +					 vm_flags);
>  }
>  #endif
>  
> @@ -1834,7 +1835,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
>  unsigned long
>  generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
>  				  unsigned long len, unsigned long pgoff,
> -				  unsigned long flags)
> +				  unsigned long flags, vm_flags_t vm_flags)
>  {
>  	struct vm_area_struct *vma, *prev;
>  	struct mm_struct *mm = current->mm;
> @@ -1887,7 +1888,8 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
>  			       unsigned long len, unsigned long pgoff,
>  			       unsigned long flags, vm_flags_t vm_flags)
>  {
> -	return generic_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
> +	return generic_get_unmapped_area_topdown(filp, addr, len, pgoff, flags,
> +						 vm_flags);
>  }
>  #endif
>  
>
> -- 
> 2.39.2