Re: [PATCH 22/32] x86, pkeys: dump PTE pkey in /proc/pid/smaps
From: Vlastimil Babka
Date: Tue Jan 05 2016 - 08:32:53 EST
On 12/14/2015 08:06 PM, Dave Hansen wrote:
From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
$SUBJ is a bit confusing in that it's dumping stuff from VMA, not PTE's?
It could be also useful to extend dump_vma() appropriately. Currently
there are no string translations for the new "flags" (but one can figure
it out from the raw value). But maybe we should print pkey separately in
dump_vma() as you do here. I have a series in flight [1] that touches
dump_vma() and the flags printing in general, so to avoid conflicts,
handling pkeys there could wait. But mentioning it now for less chance
of being forgotten...
[1] https://lkml.org/lkml/2015/12/18/178 - a previous version is in
mmotm and this should replace it after 4.5-rc1
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.
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
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 2015-12-14 10:42:48.777070739 -0800
+++ b/arch/x86/kernel/setup.c 2015-12-14 10:42:48.782070963 -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 2015-12-14 10:42:48.779070829 -0800
+++ b/fs/proc/task_mmu.c 2015-12-14 10:42:48.783071008 -0800
@@ -615,11 +615,20 @@ 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]);
@@ -657,6 +666,10 @@ 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)
+{
+}
+
static int show_smap(struct seq_file *m, void *v, int is_pid)
{
struct vm_area_struct *vma = v;
@@ -713,6 +726,7 @@ 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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