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[RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers

Started byRam Pai <linuxram@us.ibm.com>
First post2017-07-05 23:40 +0200
Last post2017-07-14 01:30 +0200
Articles 5 — 2 participants

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  [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers Ram Pai <linuxram@us.ibm.com> - 2017-07-05 23:40 +0200
    Re: [RFC v5 15/38] powerpc: helper function to read,write  AMR,IAMR,UAMOR registers Balbir Singh <bsingharora@gmail.com> - 2017-07-12 07:30 +0200
      Re: [RFC v5 15/38] powerpc: helper function to read,write  AMR,IAMR,UAMOR registers Ram Pai <linuxram@us.ibm.com> - 2017-07-13 10:00 +0200
        Re: [RFC v5 15/38] powerpc: helper function to read,write  AMR,IAMR,UAMOR registers Balbir Singh <bsingharora@gmail.com> - 2017-07-13 11:50 +0200
          Re: [RFC v5 15/38] powerpc: helper function to read,write  AMR,IAMR,UAMOR registers Ram Pai <linuxram@us.ibm.com> - 2017-07-14 01:30 +0200

#1681866 — [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers

FromRam Pai <linuxram@us.ibm.com>
Date2017-07-05 23:40 +0200
Subject[RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers
Message-ID<u00bF-3nZ-45@gated-at.bofh.it>
Implements helper functions to read and write the key related
registers; AMR, IAMR, UAMOR.

AMR register tracks the read,write permission of a key
IAMR register tracks the execute permission of a key
UAMOR register enables and disables a key

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
 arch/powerpc/include/asm/book3s/64/pgtable.h |   60 ++++++++++++++++++++++++++
 1 files changed, 60 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 85bc987..435d6a7 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -428,6 +428,66 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
 		pte_update(mm, addr, ptep, 0, _PAGE_PRIVILEGED, 1);
 }
 
+#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
+
+#include <asm/reg.h>
+static inline u64 read_amr(void)
+{
+	return mfspr(SPRN_AMR);
+}
+static inline void write_amr(u64 value)
+{
+	mtspr(SPRN_AMR, value);
+}
+static inline u64 read_iamr(void)
+{
+	return mfspr(SPRN_IAMR);
+}
+static inline void write_iamr(u64 value)
+{
+	mtspr(SPRN_IAMR, value);
+}
+static inline u64 read_uamor(void)
+{
+	return mfspr(SPRN_UAMOR);
+}
+static inline void write_uamor(u64 value)
+{
+	mtspr(SPRN_UAMOR, value);
+}
+
+#else /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
+
+static inline u64 read_amr(void)
+{
+	WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__);
+	return -1;
+}
+static inline void write_amr(u64 value)
+{
+	WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__);
+}
+static inline u64 read_uamor(void)
+{
+	WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__);
+	return -1;
+}
+static inline void write_uamor(u64 value)
+{
+	WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__);
+}
+static inline u64 read_iamr(void)
+{
+	WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__);
+	return -1;
+}
+static inline void write_iamr(u64 value)
+{
+	WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__);
+}
+
+#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
+
 #define __HAVE_ARCH_PTEP_GET_AND_CLEAR
 static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
 				       unsigned long addr, pte_t *ptep)
-- 
1.7.1

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#1685528 — Re: [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers

FromBalbir Singh <bsingharora@gmail.com>
Date2017-07-12 07:30 +0200
SubjectRe: [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers
Message-ID<u2inL-3S5-15@gated-at.bofh.it>
In reply to#1681866
On Wed,  5 Jul 2017 14:21:52 -0700
Ram Pai <linuxram@us.ibm.com> wrote:

> Implements helper functions to read and write the key related
> registers; AMR, IAMR, UAMOR.
> 
> AMR register tracks the read,write permission of a key
> IAMR register tracks the execute permission of a key
> UAMOR register enables and disables a key
> 
> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
> ---
>  arch/powerpc/include/asm/book3s/64/pgtable.h |   60 ++++++++++++++++++++++++++
>  1 files changed, 60 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index 85bc987..435d6a7 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -428,6 +428,66 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
>  		pte_update(mm, addr, ptep, 0, _PAGE_PRIVILEGED, 1);
>  }
>  
> +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
> +
> +#include <asm/reg.h>
> +static inline u64 read_amr(void)
> +{
> +	return mfspr(SPRN_AMR);
> +}
> +static inline void write_amr(u64 value)
> +{
> +	mtspr(SPRN_AMR, value);
> +}
> +static inline u64 read_iamr(void)
> +{
> +	return mfspr(SPRN_IAMR);
> +}
> +static inline void write_iamr(u64 value)
> +{
> +	mtspr(SPRN_IAMR, value);
> +}
> +static inline u64 read_uamor(void)
> +{
> +	return mfspr(SPRN_UAMOR);
> +}
> +static inline void write_uamor(u64 value)
> +{
> +	mtspr(SPRN_UAMOR, value);
> +}
> +
> +#else /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
> +
> +static inline u64 read_amr(void)
> +{
> +	WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__);
> +	return -1;
> +}

Why do we need to have a version here if we are going to WARN(), why not
let the compilation fail if called from outside of CONFIG_PPC64_MEMORY_PROTECTION_KEYS?
Is that the intention?

Balbir Singh

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#1686336 — Re: [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers

FromRam Pai <linuxram@us.ibm.com>
Date2017-07-13 10:00 +0200
SubjectRe: [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers
Message-ID<u2Hct-2Mh-5@gated-at.bofh.it>
In reply to#1685528
On Wed, Jul 12, 2017 at 03:26:01PM +1000, Balbir Singh wrote:
> On Wed,  5 Jul 2017 14:21:52 -0700
> Ram Pai <linuxram@us.ibm.com> wrote:
> 
> > Implements helper functions to read and write the key related
> > registers; AMR, IAMR, UAMOR.
> > 
> > AMR register tracks the read,write permission of a key
> > IAMR register tracks the execute permission of a key
> > UAMOR register enables and disables a key
> > 
> > Signed-off-by: Ram Pai <linuxram@us.ibm.com>
> > ---
> >  arch/powerpc/include/asm/book3s/64/pgtable.h |   60 ++++++++++++++++++++++++++
> >  1 files changed, 60 insertions(+), 0 deletions(-)
> > 
> > diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> > index 85bc987..435d6a7 100644
> > --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> > +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> > @@ -428,6 +428,66 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
> >  		pte_update(mm, addr, ptep, 0, _PAGE_PRIVILEGED, 1);
> >  }
> >  
> > +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
> > +
> > +#include <asm/reg.h>
> > +static inline u64 read_amr(void)
> > +{
> > +	return mfspr(SPRN_AMR);
> > +}
> > +static inline void write_amr(u64 value)
> > +{
> > +	mtspr(SPRN_AMR, value);
> > +}
> > +static inline u64 read_iamr(void)
> > +{
> > +	return mfspr(SPRN_IAMR);
> > +}
> > +static inline void write_iamr(u64 value)
> > +{
> > +	mtspr(SPRN_IAMR, value);
> > +}
> > +static inline u64 read_uamor(void)
> > +{
> > +	return mfspr(SPRN_UAMOR);
> > +}
> > +static inline void write_uamor(u64 value)
> > +{
> > +	mtspr(SPRN_UAMOR, value);
> > +}
> > +
> > +#else /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
> > +
> > +static inline u64 read_amr(void)
> > +{
> > +	WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__);
> > +	return -1;
> > +}
> 
> Why do we need to have a version here if we are going to WARN(), why not
> let the compilation fail if called from outside of CONFIG_PPC64_MEMORY_PROTECTION_KEYS?
> Is that the intention?

I did not want to stop someone; kernel module for example, from calling
these interfaces from outside the pkey domain.

Either way can be argued to be correct, I suppose.
RP

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#1686414 — Re: [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers

FromBalbir Singh <bsingharora@gmail.com>
Date2017-07-13 11:50 +0200
SubjectRe: [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers
Message-ID<u2IUW-3VU-17@gated-at.bofh.it>
In reply to#1686336
On Thu, Jul 13, 2017 at 5:55 PM, Ram Pai <linuxram@us.ibm.com> wrote:
> On Wed, Jul 12, 2017 at 03:26:01PM +1000, Balbir Singh wrote:
>> On Wed,  5 Jul 2017 14:21:52 -0700
>> Ram Pai <linuxram@us.ibm.com> wrote:
>>
>> > Implements helper functions to read and write the key related
>> > registers; AMR, IAMR, UAMOR.
>> >
>> > AMR register tracks the read,write permission of a key
>> > IAMR register tracks the execute permission of a key
>> > UAMOR register enables and disables a key
>> >
>> > Signed-off-by: Ram Pai <linuxram@us.ibm.com>
>> > ---
>> >  arch/powerpc/include/asm/book3s/64/pgtable.h |   60 ++++++++++++++++++++++++++
>> >  1 files changed, 60 insertions(+), 0 deletions(-)
>> >
>> > diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
>> > index 85bc987..435d6a7 100644
>> > --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
>> > +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
>> > @@ -428,6 +428,66 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
>> >             pte_update(mm, addr, ptep, 0, _PAGE_PRIVILEGED, 1);
>> >  }
>> >
>> > +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
>> > +
>> > +#include <asm/reg.h>
>> > +static inline u64 read_amr(void)
>> > +{
>> > +   return mfspr(SPRN_AMR);
>> > +}
>> > +static inline void write_amr(u64 value)
>> > +{
>> > +   mtspr(SPRN_AMR, value);
>> > +}
>> > +static inline u64 read_iamr(void)
>> > +{
>> > +   return mfspr(SPRN_IAMR);
>> > +}
>> > +static inline void write_iamr(u64 value)
>> > +{
>> > +   mtspr(SPRN_IAMR, value);
>> > +}
>> > +static inline u64 read_uamor(void)
>> > +{
>> > +   return mfspr(SPRN_UAMOR);
>> > +}
>> > +static inline void write_uamor(u64 value)
>> > +{
>> > +   mtspr(SPRN_UAMOR, value);
>> > +}
>> > +
>> > +#else /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
>> > +
>> > +static inline u64 read_amr(void)
>> > +{
>> > +   WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__);
>> > +   return -1;
>> > +}
>>
>> Why do we need to have a version here if we are going to WARN(), why not
>> let the compilation fail if called from outside of CONFIG_PPC64_MEMORY_PROTECTION_KEYS?
>> Is that the intention?
>
> I did not want to stop someone; kernel module for example, from calling
> these interfaces from outside the pkey domain.
>
> Either way can be argued to be correct, I suppose.

Nope, build failures are better than run time failures, otherwise the
kernel will split its guts warning and warning here.

Balbir Singh.

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#1686985 — Re: [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers

FromRam Pai <linuxram@us.ibm.com>
Date2017-07-14 01:30 +0200
SubjectRe: [RFC v5 15/38] powerpc: helper function to read,write AMR,IAMR,UAMOR registers
Message-ID<u2VIu-3Dh-11@gated-at.bofh.it>
In reply to#1686414
On Thu, Jul 13, 2017 at 07:49:05PM +1000, Balbir Singh wrote:
> On Thu, Jul 13, 2017 at 5:55 PM, Ram Pai <linuxram@us.ibm.com> wrote:
> > On Wed, Jul 12, 2017 at 03:26:01PM +1000, Balbir Singh wrote:
> >> On Wed,  5 Jul 2017 14:21:52 -0700
> >> Ram Pai <linuxram@us.ibm.com> wrote:
> >>
> >> > Implements helper functions to read and write the key related
> >> > registers; AMR, IAMR, UAMOR.
> >> >
> >> > AMR register tracks the read,write permission of a key
> >> > IAMR register tracks the execute permission of a key
> >> > UAMOR register enables and disables a key
> >> >
> >> > Signed-off-by: Ram Pai <linuxram@us.ibm.com>
> >> > ---
> >> >  arch/powerpc/include/asm/book3s/64/pgtable.h |   60 ++++++++++++++++++++++++++
> >> >  1 files changed, 60 insertions(+), 0 deletions(-)
> >> >
> >> > diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> >> > index 85bc987..435d6a7 100644
> >> > --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> >> > +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> >> > @@ -428,6 +428,66 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
> >> >             pte_update(mm, addr, ptep, 0, _PAGE_PRIVILEGED, 1);
> >> >  }
> >> >
> >> > +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
> >> > +
> >> > +#include <asm/reg.h>
> >> > +static inline u64 read_amr(void)
> >> > +{
> >> > +   return mfspr(SPRN_AMR);
> >> > +}
> >> > +static inline void write_amr(u64 value)
> >> > +{
> >> > +   mtspr(SPRN_AMR, value);
> >> > +}
> >> > +static inline u64 read_iamr(void)
> >> > +{
> >> > +   return mfspr(SPRN_IAMR);
> >> > +}
> >> > +static inline void write_iamr(u64 value)
> >> > +{
> >> > +   mtspr(SPRN_IAMR, value);
> >> > +}
> >> > +static inline u64 read_uamor(void)
> >> > +{
> >> > +   return mfspr(SPRN_UAMOR);
> >> > +}
> >> > +static inline void write_uamor(u64 value)
> >> > +{
> >> > +   mtspr(SPRN_UAMOR, value);
> >> > +}
> >> > +
> >> > +#else /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
> >> > +
> >> > +static inline u64 read_amr(void)
> >> > +{
> >> > +   WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__);
> >> > +   return -1;
> >> > +}
> >>
> >> Why do we need to have a version here if we are going to WARN(), why not
> >> let the compilation fail if called from outside of CONFIG_PPC64_MEMORY_PROTECTION_KEYS?
> >> Is that the intention?
> >
> > I did not want to stop someone; kernel module for example, from calling
> > these interfaces from outside the pkey domain.
> >
> > Either way can be argued to be correct, I suppose.
> 
> Nope, build failures are better than run time failures, otherwise the
> kernel will split its guts warning and warning here.
> 

Well these are helper functions that can be called by anyone under
any situation. I will rather have them defined unconditionally; under
no ifdefs.  No spewing of warnings anymore. The registers will
be read or written as told. It just makes sense that way.

RP

-- 
Ram Pai

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