[PATCH v7 3/5] powerpc: Rework and improve STRICT_KERNEL_RWX patching

[Christophe Leroy]

Hi Jordan

Le 10/11/2021 à 01:37, Jordan Niethe a écrit :
> From: "Christopher M. Riedl" <cmr at bluescreens.de>
> 
> Rework code-patching with STRICT_KERNEL_RWX to prepare for a later patch
> which uses a temporary mm for patching under the Book3s64 Radix MMU.
> Make improvements by adding a WARN_ON when the patchsite doesn't match
> after patching and return the error from __patch_instruction() properly.
> 
> Signed-off-by: Christopher M. Riedl <cmr at bluescreens.de>
> Signed-off-by: Jordan Niethe <jniethe5 at gmail.com>
> ---
> v7: still pass addr to map_patch_area()


This patch doesn-t apply, can you rebase the series ?

Thanks
Christophe

> ---
>   arch/powerpc/lib/code-patching.c | 20 ++++++++++----------
>   1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
> index 29a30c3068ff..d586bf9c7581 100644
> --- a/arch/powerpc/lib/code-patching.c
> +++ b/arch/powerpc/lib/code-patching.c
> @@ -75,6 +75,7 @@ static inline void stop_using_temp_mm(struct temp_mm_state prev_state)
>   }
>   
>   static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
> +static DEFINE_PER_CPU(unsigned long, cpu_patching_addr);
>   
>   static int text_area_cpu_up(unsigned int cpu)
>   {
> @@ -87,6 +88,7 @@ static int text_area_cpu_up(unsigned int cpu)
>   		return -1;
>   	}
>   	this_cpu_write(text_poke_area, area);
> +	this_cpu_write(cpu_patching_addr, (unsigned long)area->addr);
>   
>   	return 0;
>   }
> @@ -172,11 +174,10 @@ static inline int unmap_patch_area(unsigned long addr)
>   
>   static int do_patch_instruction(u32 *addr, struct ppc_inst instr)
>   {
> -	int err;
> +	int err, rc = 0;
>   	u32 *patch_addr = NULL;
>   	unsigned long flags;
>   	unsigned long text_poke_addr;
> -	unsigned long kaddr = (unsigned long)addr;
>   
>   	/*
>   	 * During early early boot patch_instruction is called
> @@ -188,15 +189,13 @@ static int do_patch_instruction(u32 *addr, struct ppc_inst instr)
>   
>   	local_irq_save(flags);
>   
> -	text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
> -	if (map_patch_area(addr, text_poke_addr)) {
> -		err = -1;
> +	text_poke_addr = __this_cpu_read(cpu_patching_addr);
> +	err = map_patch_area(addr, text_poke_addr);
> +	if (err)
>   		goto out;
> -	}
> -
> -	patch_addr = (u32 *)(text_poke_addr + (kaddr & ~PAGE_MASK));
>   
> -	__patch_instruction(addr, instr, patch_addr);
> +	patch_addr = (u32 *)(text_poke_addr | offset_in_page(addr));
> +	rc = __patch_instruction(addr, instr, patch_addr);
>   
>   	err = unmap_patch_area(text_poke_addr);
>   	if (err)
> @@ -204,8 +203,9 @@ static int do_patch_instruction(u32 *addr, struct ppc_inst instr)
>   
>   out:
>   	local_irq_restore(flags);
> +	WARN_ON(!ppc_inst_equal(ppc_inst_read(addr), instr));
>   
> -	return err;
> +	return rc ? rc : err;
>   }
>   #else /* !CONFIG_STRICT_KERNEL_RWX */
>