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* [PATCH] RISC-V: Don't mark init section as non-executable
@ 2020-05-31  9:57 ` Anup Patel
  0 siblings, 0 replies; 4+ messages in thread
From: Anup Patel @ 2020-05-31  9:57 UTC (permalink / raw)
  To: Palmer Dabbelt, Paul Walmsley, Albert Ou
  Cc: Atish Patra, Alistair Francis, Anup Patel, linux-riscv,
	linux-kernel, Anup Patel, stable

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>
---
 arch/riscv/mm/init.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 736de6c8739f..e0f8ccab8a41 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -482,11 +482,6 @@ static void __init setup_vm_final(void)
 
 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);
 }
 
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* [PATCH] RISC-V: Don't mark init section as non-executable
@ 2020-05-31  9:57 ` Anup Patel
  0 siblings, 0 replies; 4+ messages in thread
From: Anup Patel @ 2020-05-31  9:57 UTC (permalink / raw)
  To: Palmer Dabbelt, Paul Walmsley, Albert Ou
  Cc: Anup Patel, Anup Patel, linux-kernel, stable, Atish Patra,
	Alistair Francis, linux-riscv

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>
---
 arch/riscv/mm/init.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 736de6c8739f..e0f8ccab8a41 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -482,11 +482,6 @@ static void __init setup_vm_final(void)
 
 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);
 }
 
-- 
2.25.1



^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH] RISC-V: Don't mark init section as non-executable
  2020-05-31  9:57 ` Anup Patel
@ 2020-06-01  4:20   ` Anup Patel
  -1 siblings, 0 replies; 4+ messages in thread
From: Anup Patel @ 2020-06-01  4:20 UTC (permalink / raw)
  To: Anup Patel
  Cc: Palmer Dabbelt, Paul Walmsley, Albert Ou, Atish Patra,
	Alistair Francis, linux-riscv, linux-kernel@vger.kernel.org List,
	stable

On Sun, May 31, 2020 at 3:28 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>
> ---
>  arch/riscv/mm/init.c | 5 -----
>  1 file changed, 5 deletions(-)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 736de6c8739f..e0f8ccab8a41 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -482,11 +482,6 @@ static void __init setup_vm_final(void)
>
>  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);
>  }

I just realized that updated free_initmem() over here is exactly
same as generic free_initmem() defined in init/main.c so it's better
to remove free_initmem() from here. I will send v2.

Regards,
Anup

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] RISC-V: Don't mark init section as non-executable
@ 2020-06-01  4:20   ` Anup Patel
  0 siblings, 0 replies; 4+ messages in thread
From: Anup Patel @ 2020-06-01  4:20 UTC (permalink / raw)
  To: Anup Patel
  Cc: Albert Ou, linux-kernel@vger.kernel.org List, stable,
	Atish Patra, Alistair Francis, Paul Walmsley, Palmer Dabbelt,
	linux-riscv

On Sun, May 31, 2020 at 3:28 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>
> ---
>  arch/riscv/mm/init.c | 5 -----
>  1 file changed, 5 deletions(-)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 736de6c8739f..e0f8ccab8a41 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -482,11 +482,6 @@ static void __init setup_vm_final(void)
>
>  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);
>  }

I just realized that updated free_initmem() over here is exactly
same as generic free_initmem() defined in init/main.c so it's better
to remove free_initmem() from here. I will send v2.

Regards,
Anup


^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-06-01  4:20 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2020-05-31  9:57 [PATCH] RISC-V: Don't mark init section as non-executable Anup Patel
2020-05-31  9:57 ` Anup Patel
2020-06-01  4:20 ` Anup Patel
2020-06-01  4:20   ` Anup Patel

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