Re: [PATCH v12 3/3] mm, x86, powerpc: display pkey in smaps only if arch supports pkeys

[Dave Hansen]

On 02/21/2018 03:52 PM, Ram Pai wrote:
> Currently the  architecture  specific code is expected to
> display  the  protection  keys  in  smap  for a given vma.
> This can lead to redundant code and possibly to divergent
> formats in which the key gets displayed.
> 
> This  patch  changes  the implementation. It displays the
> pkey only if the architecture support pkeys, i.e
> arch_pkeys_enabled() returns true.  This patch
> provides x86 implementation for arch_pkeys_enabled().
> 
> x86 arch_show_smap() function is not needed anymore.
> Deleting it.

This looks fine to me.  Thanks for doing these, Ram.

Reviewed-by: Dave Hansen 

[PATCH v12 3/3] mm, x86, powerpc: display pkey in smaps only if arch supports pkeys

[Ram Pai]

Currently the  architecture  specific code is expected to
display  the  protection  keys  in  smap  for a given vma.
This can lead to redundant code and possibly to divergent
formats in which the key gets displayed.

This  patch  changes  the implementation. It displays the
pkey only if the architecture support pkeys, i.e
arch_pkeys_enabled() returns true.  This patch
provides x86 implementation for arch_pkeys_enabled().

x86 arch_show_smap() function is not needed anymore.
Deleting it.

cc: Dave Hansen 
cc: Michael Ellermen 
cc: Benjamin Herrenschmidt 
cc: Andrew Morton 
Signed-off-by: Thiago Jung Bauermann 
(fixed compilation errors for x86 configs)
Acked-by: Michal Hocko 
Reviewed-by: Ingo Molnar 
Signed-off-by: Ram Pai 
---
 arch/powerpc/include/asm/mmu_context.h |5 -
 arch/x86/include/asm/mmu_context.h |5 -
 arch/x86/include/asm/pkeys.h   |1 +
 arch/x86/kernel/fpu/xstate.c   |5 +
 arch/x86/kernel/setup.c|8 
 fs/proc/task_mmu.c |   10 +-
 include/linux/pkeys.h  |7 ++-
 7 files changed, 17 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu_context.h 
b/arch/powerpc/include/asm/mmu_context.h
index 051b3d6..566b3c2 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -203,11 +203,6 @@ static inline bool arch_vma_access_permitted(struct 
vm_area_struct *vma,
 #define thread_pkey_regs_restore(new_thread, old_thread)
 #define thread_pkey_regs_init(thread)
 
-static inline int vma_pkey(struct vm_area_struct *vma)
-{
-   return 0;
-}
-
 static inline u64 pte_to_hpte_pkey_bits(u64 pteflags)
 {
return 0x0UL;
diff --git a/arch/x86/include/asm/mmu_context.h 
b/arch/x86/include/asm/mmu_context.h
index c931b88..134f3a0 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -294,11 +294,6 @@ static inline int vma_pkey(struct vm_area_struct *vma)
 
return (vma->vm_flags & vma_pkey_mask) >> VM_PKEY_SHIFT;
 }
-#else
-static inline int vma_pkey(struct vm_area_struct *vma)
-{
-   return 0;
-}
 #endif
 
 /*
diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h
index a0ba1ff..f6c287b 100644
--- a/arch/x86/include/asm/pkeys.h
+++ b/arch/x86/include/asm/pkeys.h
@@ -6,6 +6,7 @@
 
 extern int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
unsigned long init_val);
+extern bool arch_pkeys_enabled(void);
 
 /*
  * Try to dedicate one of the protection keys to be used as an
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 87a57b7..4f566e9 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -945,6 +945,11 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int 
pkey,
 
return 0;
 }
+
+bool arch_pkeys_enabled(void)
+{
+   return boot_cpu_has(X86_FEATURE_OSPKE);
+}
 #endif /* ! CONFIG_ARCH_HAS_PKEYS */
 
 /*
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 1ae67e9..d0539e3 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1314,11 +1314,3 @@ static int __init register_kernel_offset_dumper(void)
return 0;
 }
 __initcall(register_kernel_offset_dumper);
-
-void arch_show_smap(struct seq_file *m, struct vm_area_struct *vma)
-{
-   if (!boot_cpu_has(X86_FEATURE_OSPKE))
-   return;
-
-   seq_printf(m, "ProtectionKey:  %8u\n", vma_pkey(vma));
-}
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 6d83bb7..70aa912 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -18,10 +18,12 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 #include 
 #include 
+#include 
 #include "internal.h"
 
 void task_mem(struct seq_file *m, struct mm_struct *mm)
@@ -733,10 +735,6 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long 
hmask,
 }
 #endif /* HUGETLB_PAGE */
 
-void __weak arch_show_smap(struct seq_file *m, struct vm_area_struct *vma)
-{
-}
-
 static int show_smap(struct seq_file *m, void *v, int is_pid)
 {
struct proc_maps_private *priv = m->private;
@@ -856,9 +854,11 @@ static int show_smap(struct seq_file *m, void *v, int 
is_pid)
   (unsigned long)(mss->pss >> (10 + PSS_SHIFT)));
 
if (!rollup_mode) {
-   arch_show_smap(m, vma);
+   if (arch_pkeys_enabled())
+   seq_printf(m, "ProtectionKey:  %8u\n", vma_pkey(vma));
show_smap_vma_flags(m, vma);
}
+
m_cache_vma(m, vma);
return ret;
 }
diff --git a/include/linux/pkeys.h b/include/linux/pkeys.h
index 0794ca7..49dff15 100644
--- a/include/linux/pkeys.h
+++ b/include/linux/pkeys.h
@@ -3,7 +3,6 @@
 #define _LINUX_PKEYS_H