[PATCH 17/26] x86, pkeys: dump PTE pkey in /proc/pid/smaps

[Dave Hansen]

The protection key can now be just as important as read/write
permissions on a VMA.  We need some debug mechanism to help
figure out if it is in play.  smaps seems like a logical
place to expose it.

arch/x86/kernel/setup.c is a bit of a weirdo place to put
this code, but it already had seq_file.h and there was not
a much better existing place to put it.

We also use no #ifdef.  If protection keys is .config'd out
we will get the same function as if we used the weak generic
function.

---

 b/arch/x86/kernel/setup.c |    9 +++++++++
 b/fs/proc/task_mmu.c      |    5 +++++
 2 files changed, 14 insertions(+)

diff -puN arch/x86/kernel/setup.c~pkeys-40-smaps arch/x86/kernel/setup.c
--- a/arch/x86/kernel/setup.c~pkeys-40-smaps	2015-09-16 10:48:18.838309381 -0700
+++ b/arch/x86/kernel/setup.c	2015-09-16 10:48:18.844309653 -0700
@@ -111,6 +111,7 @@
 #include <asm/mce.h>
 #include <asm/alternative.h>
 #include <asm/prom.h>
+#include <asm/special_insns.h>
 
 /*
  * max_low_pfn_mapped: highest direct mapped pfn under 4GB
@@ -1264,3 +1265,11 @@ static int __init register_kernel_offset
 	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 -puN fs/proc/task_mmu.c~pkeys-40-smaps fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~pkeys-40-smaps	2015-09-16 10:48:18.840309472 -0700
+++ b/fs/proc/task_mmu.c	2015-09-16 10:48:18.844309653 -0700
@@ -625,6 +625,10 @@ static void show_smap_vma_flags(struct s
 	seq_putc(m, '\n');
 }
 
+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 vm_area_struct *vma = v;
@@ -674,6 +678,7 @@ static int show_smap(struct seq_file *m,
 		   (vma->vm_flags & VM_LOCKED) ?
 			(unsigned long)(mss.pss >> (10 + PSS_SHIFT)) : 0);
 
+	arch_show_smap(m, vma);
 	show_smap_vma_flags(m, vma);
 	m_cache_vma(m, vma);
 	return 0;
_
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