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Date: Tue, 2 Feb 2016 17:11:56 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Dave Hansen <dave@...1.net>, linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org, x86@...nel.org, torvalds@...ux-foundation.org,
dave.hansen@...ux.intel.com
Subject: Re: [PATCH 22/31] x86, pkeys: dump pkey from VMA in /proc/pid/smaps
On 01/29/2016 07:17 PM, Dave Hansen wrote:
> From: Dave Hansen <dave.hansen@...ux.intel.com>
>
> 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@...ux.intel.com>
> Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: vbabka@...e.cz
> ---
>
> 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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