Re: [PATCH 22/31] x86, pkeys: dump pkey from VMA in /proc/pid/smaps

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On 01/29/2016 07:17 PM, Dave Hansen wrote:
From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>

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 effectively get the same function as if we used the weak
generic function.

Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: vbabka@xxxxxxx
---

  b/arch/x86/kernel/setup.c |    9 +++++++++
  b/fs/proc/task_mmu.c      |   14 ++++++++++++++
  2 files changed, 23 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	2016-01-28 15:52:26.386680200 -0800
+++ b/arch/x86/kernel/setup.c	2016-01-28 15:52:26.391680429 -0800
@@ -112,6 +112,7 @@
  #include <asm/alternative.h>
  #include <asm/prom.h>
  #include <asm/microcode.h>
+#include <asm/mmu_context.h>

  /*
   * max_low_pfn_mapped: highest direct mapped pfn under 4GB
@@ -1282,3 +1283,11 @@ 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	2016-01-28 15:52:26.387680246 -0800
+++ b/fs/proc/task_mmu.c	2016-01-28 15:52:26.391680429 -0800
@@ -668,11 +668,20 @@ static void show_smap_vma_flags(struct s
  		[ilog2(VM_MERGEABLE)]	= "mg",
  		[ilog2(VM_UFFD_MISSING)]= "um",
  		[ilog2(VM_UFFD_WP)]	= "uw",
+#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+		/* These come out via ProtectionKey: */
+		[ilog2(VM_PKEY_BIT0)]	= "",
+		[ilog2(VM_PKEY_BIT1)]	= "",
+		[ilog2(VM_PKEY_BIT2)]	= "",
+		[ilog2(VM_PKEY_BIT3)]	= "",
+#endif
  	};
  	size_t i;

  	seq_puts(m, "VmFlags: ");
  	for (i = 0; i < BITS_PER_LONG; i++) {
+		if (!mnemonics[i][0])
+			continue;
  		if (vma->vm_flags & (1UL << i)) {
  			seq_printf(m, "%c%c ",
  				   mnemonics[i][0], mnemonics[i][1]);
@@ -710,6 +719,10 @@ static int smaps_hugetlb_range(pte_t *pt
  }
  #endif /* HUGETLB_PAGE */

+void __weak arch_show_smap(struct seq_file *m, struct vm_area_struct *vma)
+{
+}

Is it valid that this serves also as a declaration? Or should it be also in some header?

+
  static int show_smap(struct seq_file *m, void *v, int is_pid)
  {
  	struct vm_area_struct *vma = v;
@@ -791,6 +804,7 @@ 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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