Re: [PATCH v4 13/29] arm64: convert protection key into vm_flags and pgprot values

On Thu, Jul 04, 2024 at 01:47:04PM +0100, Joey Gouly wrote:

On Wed, Jun 19, 2024 at 05:45:29PM +0100, Catalin Marinas wrote:

quoted

On Tue, May 28, 2024 at 12:24:57PM +0530, Amit Daniel Kachhap wrote:

quoted

On 5/3/24 18:31, Joey Gouly wrote:

quoted

diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h
index 5966ee4a6154..ecb2d18dc4d7 100644
--- a/arch/arm64/include/asm/mman.h
+++ b/arch/arm64/include/asm/mman.h

@@ -7,7 +7,7 @@
  #include <uapi/asm/mman.h>
  static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
-	unsigned long pkey __always_unused)
+	unsigned long pkey)
  {
  	unsigned long ret = 0;

@@ -17,6 +17,12 @@ static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
  	if (system_supports_mte() && (prot & PROT_MTE))
  		ret |= VM_MTE;
+#if defined(CONFIG_ARCH_HAS_PKEYS)

Should there be system_supports_poe() check like above?

I think it should, otherwise we end up with these bits in the pte even
when POE is not supported.

I think it can't get here due to the flow of the code, but I will add it to be
defensive (since it's just an alternative that gets patched).

You are probably right, the mprotect_pkey() will reject the call if we
don't support POE. So you could add a comment instead (but a
system_supports_poe() check seems safer).

I still need the defined(CONFIG_ARCH_HAS_PKEYS) check, since the VM_PKEY_BIT*
are only defined then.

Yes, the ifdef will stay.

-- 
Catalin