[PATCH v2] RISC-V: Don't mark init section as non-executable

[PATCH v2] RISC-V: Don't mark init section as non-executable

[Anup Patel]

The head text section (i.e. _start, secondary_start_sbi, etc) and the
init section fall under same page table level-1 mapping.

Currently, the runtime CPU hotplug is broken because we are marking
init section as non-executable which in-turn marks head text section
as non-executable.

Further investigating other architectures, it seems marking the init
section as non-executable is redundant because the init section pages
are anyway poisoned and freed.

To fix broken runtime CPU hotplug, we simply remove the code marking
the init section as non-executable.

Fixes: d27c3c90817e ("riscv: add STRICT_KERNEL_RWX support")
Cc: stable@vger.kernel.org
Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
Changes since v1:
 - Updated free_initmem() is same as generic free_initmem() defined in
   init/main.c so we completely remove free_initmem() from arch/riscv
---
 arch/riscv/mm/init.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 736de6c8739f..fdc772f57edc 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -479,17 +479,6 @@ static void __init setup_vm_final(void)
 	csr_write(CSR_SATP, PFN_DOWN(__pa_symbol(swapper_pg_dir)) | SATP_MODE);
 	local_flush_tlb_all();
 }
-
-void free_initmem(void)
-{
-	unsigned long init_begin = (unsigned long)__init_begin;
-	unsigned long init_end = (unsigned long)__init_end;
-
-	/* Make the region as non-execuatble. */
-	set_memory_nx(init_begin, (init_end - init_begin) >> PAGE_SHIFT);
-	free_initmem_default(POISON_FREE_INITMEM);
-}
-
 #else
 asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 {
-- 
2.25.1

Re: [PATCH v2] RISC-V: Don't mark init section as non-executable

[Zong Li]

Anup Patel <anup.patel@wdc.com> 於 2020年6月1日 週一 下午1:07寫道：
>
> The head text section (i.e. _start, secondary_start_sbi, etc) and the
> init section fall under same page table level-1 mapping.
>
> Currently, the runtime CPU hotplug is broken because we are marking
> init section as non-executable which in-turn marks head text section
> as non-executable.
>
> Further investigating other architectures, it seems marking the init
> section as non-executable is redundant because the init section pages
> are anyway poisoned and freed.
>
> To fix broken runtime CPU hotplug, we simply remove the code marking
> the init section as non-executable.
>
> Fixes: d27c3c90817e ("riscv: add STRICT_KERNEL_RWX support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Anup Patel <anup.patel@wdc.com>
> ---
> Changes since v1:
>  - Updated free_initmem() is same as generic free_initmem() defined in
>    init/main.c so we completely remove free_initmem() from arch/riscv
> ---
>  arch/riscv/mm/init.c | 11 -----------
>  1 file changed, 11 deletions(-)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 736de6c8739f..fdc772f57edc 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -479,17 +479,6 @@ static void __init setup_vm_final(void)
>         csr_write(CSR_SATP, PFN_DOWN(__pa_symbol(swapper_pg_dir)) | SATP_MODE);
>         local_flush_tlb_all();
>  }
> -
> -void free_initmem(void)
> -{
> -       unsigned long init_begin = (unsigned long)__init_begin;
> -       unsigned long init_end = (unsigned long)__init_end;
> -
> -       /* Make the region as non-execuatble. */
> -       set_memory_nx(init_begin, (init_end - init_begin) >> PAGE_SHIFT);
> -       free_initmem_default(POISON_FREE_INITMEM);
> -}
> -
>  #else
>  asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>  {
> --
> 2.25.1
>
>

It looks good to me.
Reviewed-by: Zong Li <zong.li@sifive.com>

Re: [PATCH v2] RISC-V: Don't mark init section as non-executable

[Atish Patra]

On Sun, May 31, 2020 at 10:07 PM Anup Patel <anup.patel@wdc.com> wrote:
>
> The head text section (i.e. _start, secondary_start_sbi, etc) and the
> init section fall under same page table level-1 mapping.
>
> Currently, the runtime CPU hotplug is broken because we are marking
> init section as non-executable which in-turn marks head text section
> as non-executable.
>
> Further investigating other architectures, it seems marking the init
> section as non-executable is redundant because the init section pages
> are anyway poisoned and freed.
>
> To fix broken runtime CPU hotplug, we simply remove the code marking
> the init section as non-executable.
>
> Fixes: d27c3c90817e ("riscv: add STRICT_KERNEL_RWX support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Anup Patel <anup.patel@wdc.com>
> ---
> Changes since v1:
>  - Updated free_initmem() is same as generic free_initmem() defined in
>    init/main.c so we completely remove free_initmem() from arch/riscv
> ---
>  arch/riscv/mm/init.c | 11 -----------
>  1 file changed, 11 deletions(-)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 736de6c8739f..fdc772f57edc 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -479,17 +479,6 @@ static void __init setup_vm_final(void)
>         csr_write(CSR_SATP, PFN_DOWN(__pa_symbol(swapper_pg_dir)) | SATP_MODE);
>         local_flush_tlb_all();
>  }
> -
> -void free_initmem(void)
> -{
> -       unsigned long init_begin = (unsigned long)__init_begin;
> -       unsigned long init_end = (unsigned long)__init_end;
> -
> -       /* Make the region as non-execuatble. */
> -       set_memory_nx(init_begin, (init_end - init_begin) >> PAGE_SHIFT);
> -       free_initmem_default(POISON_FREE_INITMEM);
> -}
> -
>  #else
>  asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>  {
> --
> 2.25.1
>
>

Reviewed-by: Atish Patra <atish.patra@wdc.com>
-- 
Regards,
Atish