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Message-Id: <20180122183351.GQ5612@ram.oc3035372033.ibm.com>
Date: Mon, 22 Jan 2018 10:33:51 -0800
From: Ram Pai <linuxram@...ibm.com>
To: corbet@....net, linux-doc@...r.kernel.org
Cc: mpe@...erman.id.au, linuxppc-dev@...ts.ozlabs.org,
linux-mm@...ck.org, x86@...nel.org, linux-arch@...r.kernel.org,
linux-kernel@...r.kernel.org, mingo@...hat.com,
akpm@...ux-foundation.org, dave.hansen@...el.com,
benh@...nel.crashing.org, paulus@...ba.org,
khandual@...ux.vnet.ibm.com, aneesh.kumar@...ux.vnet.ibm.com,
bsingharora@...il.com, hbabu@...ibm.com, mhocko@...nel.org,
bauerman@...ux.vnet.ibm.com, ebiederm@...ssion.com, arnd@...db.de
Subject: Re: [PATCH v10 00/27] powerpc, mm: Memory Protection Keys
Sorry please ignore this series. It was a duplication mistake.
I aborted the send midway, but a few escaped into the cyber.
RP
On Mon, Jan 22, 2018 at 10:26:29AM -0800, Ram Pai wrote:
> Memory protection keys enable applications to protect its
> address space from inadvertent access from or corruption
> by itself.
>
> These patches along with the pte-bit freeing patch series
> enables the protection key feature on powerpc; 4k and 64k
> hashpage kernels.
>
> Will send the documentation and selftest patches separately
>
> All patches can be found at --
> https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_rampai_memorykeys.git&d=DwIBAg&c=jf_iaSHvJObTbx-siA1ZOg&r=m-UrKChQVkZtnPpjbF6YY99NbT8FBByQ-E-ygV8luxw&m=Swwnka5M5weiMNnxmx35NOJUSSC3s8iQYEH4hsrCNSw&s=h7BFHYo7gWvagk3xbtcifI_3xFOO1CyWzfOtLBjWLcQ&e= memkey.v10
>
>
> The overall idea:
> -----------------
> A process allocates a key and associates it with
> an address range within its address space.
> The process then can dynamically set read/write
> permissions on the key without involving the
> kernel. Any code that violates the permissions
> of the address space; as defined by its associated
> key, will receive a segmentation fault.
>
> This patch series enables the feature on PPC64 HPTE
> platform.
>
> ISA3.0 section 5.7.13 describes the detailed
> specifications.
>
>
> Highlevel view of the design:
> ---------------------------
> When an application associates a key with a address
> address range, program the key in the Linux PTE.
> When the MMU detects a page fault, allocate a hash
> page and program the key into HPTE. And finally
> when the MMU detects a key violation; due to
> invalid application access, invoke the registered
> signal handler and provide the violated key number.
>
>
> Testing:
> -------
> This patch series has passed all the protection key
> tests available in the selftest directory.The
> tests are updated to work on both x86 and powerpc.
> The selftests have passed on x86 and powerpc hardware.
>
> History:
> -------
> version v10:
> (1) key-fault in page-fault handler
> is handled as normal fault
> and not as a bad fault.
> (2) changed device tree scanning to
> unflattened device tree.
> (3) fixed a bug in the logic that detected
> the total number of available pkeys.
> (4) dropped two patches. (i) sysfs interface
> (ii) sys_pkey_modif() syscall
>
> version v9:
> (1) used jump-labels to optimize code
> -- Balbir
> (2) fixed a register initialization bug noted
> by Balbir
> (3) fixed inappropriate use of paca to pass
> siginfo and keys to signal handler
> (4) Cleanup of comment style not to be right
> justified -- mpe
> (5) restructured the patches to depend on the
> availability of VM_PKEY_BIT4 in
> include/linux/mm.h
> (6) Incorporated comments from Dave Hansen
> towards changes to selftest and got
> them tested on x86.
>
> version v8:
> (1) Contents of the AMR register withdrawn from
> the siginfo structure. Applications can always
> read the AMR register.
> (2) AMR/IAMR/UAMOR are now available through
> ptrace system call. -- thanks to Thiago
> (3) code changes to handle legacy power cpus
> that do not support execute-disable.
> (4) incorporates many code improvement
> suggestions.
>
> version v7:
> (1) refers to device tree property to enable
> protection keys.
> (2) adds 4K PTE support.
> (3) fixes a couple of bugs noticed by Thiago
> (4) decouples this patch series from arch-
> independent code. This patch series can
> now stand by itself, with one kludge
> patch(2).
> version v7:
> (1) refers to device tree property to enable
> protection keys.
> (2) adds 4K PTE support.
> (3) fixes a couple of bugs noticed by Thiago
> (4) decouples this patch series from arch-
> independent code. This patch series can
> now stand by itself, with one kludge
> patch(2).
>
> version v6:
> (1) selftest changes are broken down into 20
> incremental patches.
> (2) A separate key allocation mask that
> includes PKEY_DISABLE_EXECUTE is
> added for powerpc
> (3) pkey feature is enabled for 64K HPT case
> only. RPT and 4k HPT is disabled.
> (4) Documentation is updated to better
> capture the semantics.
> (5) introduced arch_pkeys_enabled() to find
> if an arch enables pkeys. Correspond-
> ing change the logic that displays
> key value in smaps.
> (6) code rearranged in many places based on
> comments from Dave Hansen, Balbir,
> Anshuman.
> (7) fixed one bug where a bogus key could be
> associated successfully in
> pkey_mprotect().
>
> version v5:
> (1) reverted back to the old design -- store
> the key in the pte, instead of bypassing
> it. The v4 design slowed down the hash
> page path.
> (2) detects key violation when kernel is told
> to access user pages.
> (3) further refined the patches into smaller
> consumable units
> (4) page faults handlers captures the fault-
> ing key
> from the pte instead of the vma. This
> closes a race between where the key
> update in the vma and a key fault caused
> by the key programmed in the pte.
> (5) a key created with access-denied should
> also set it up to deny write. Fixed it.
> (6) protection-key number is displayed in
> smaps the x86 way.
>
> version v4:
> (1) patches no more depend on the pte bits
> to program the hpte
> -- comment by Balbir
> (2) documentation updates
> (3) fixed a bug in the selftest.
> (4) unlike x86, powerpc lets signal handler
> change key permission bits; the
> change will persist across signal
> handler boundaries. Earlier we
> allowed the signal handler to
> modify a field in the siginfo
> structure which would than be used
> by the kernel to program the key
> protection register (AMR)
> -- resolves a issue raised by Ben.
> "Calls to sys_swapcontext with a
> made-up context will end up with a
> crap AMR if done by code who didn't
> know about that register".
> (5) these changes enable protection keys on
> 4k-page kernel aswell.
>
> version v3:
> (1) split the patches into smaller consumable
> patches.
> (2) added the ability to disable execute
> permission on a key at creation.
> (3) rename calc_pte_to_hpte_pkey_bits() to
> pte_to_hpte_pkey_bits()
> -- suggested by Anshuman
> (4) some code optimization and clarity in
> do_page_fault()
> (5) A bug fix while invalidating a hpte slot
> in __hash_page_4K()
> -- noticed by Aneesh
>
>
> version v2:
> (1) documentation and selftest added.
> (2) fixed a bug in 4k hpte backed 64k pte
> where page invalidation was not
> done correctly, and initialization
> of second-part-of-the-pte was not
> done correctly if the pte was not
> yet Hashed with a hpte.
> -- Reported by Aneesh.
> (3) Fixed ABI breakage caused in siginfo
> structure.
> -- Reported by Anshuman.
>
>
> version v1: Initial version
>
>
> Ram Pai (26):
> mm, powerpc, x86: define VM_PKEY_BITx bits if CONFIG_ARCH_HAS_PKEYS
> is enabled
> mm, powerpc, x86: introduce an additional vma bit for powerpc pkey
> powerpc: initial pkey plumbing
> powerpc: track allocation status of all pkeys
> powerpc: helper function to read,write AMR,IAMR,UAMOR registers
> powerpc: helper functions to initialize AMR, IAMR and UAMOR registers
> powerpc: cleanup AMR, IAMR when a key is allocated or freed
> powerpc: implementation for arch_set_user_pkey_access()
> powerpc: ability to create execute-disabled pkeys
> powerpc: store and restore the pkey state across context switches
> powerpc: introduce execute-only pkey
> powerpc: ability to associate pkey to a vma
> powerpc: implementation for arch_override_mprotect_pkey()
> powerpc: map vma key-protection bits to pte key bits.
> powerpc: Program HPTE key protection bits
> powerpc: helper to validate key-access permissions of a pte
> powerpc: check key protection for user page access
> powerpc: implementation for arch_vma_access_permitted()
> powerpc: Handle exceptions caused by pkey violation
> powerpc: introduce get_mm_addr_key() helper
> powerpc: Deliver SEGV signal on pkey violation
> powerpc: Enable pkey subsystem
> powerpc: sys_pkey_alloc() and sys_pkey_free() system calls
> powerpc: sys_pkey_mprotect() system call
> mm, x86 : introduce arch_pkeys_enabled()
> mm: display pkey in smaps if arch_pkeys_enabled() is true
>
> Thiago Jung Bauermann (1):
> powerpc/ptrace: Add memory protection key regset
>
> arch/powerpc/Kconfig | 15 +
> arch/powerpc/include/asm/book3s/64/mmu-hash.h | 5 +
> arch/powerpc/include/asm/book3s/64/mmu.h | 10 +
> arch/powerpc/include/asm/book3s/64/pgtable.h | 48 +++-
> arch/powerpc/include/asm/bug.h | 1 +
> arch/powerpc/include/asm/cputable.h | 16 +-
> arch/powerpc/include/asm/mman.h | 13 +-
> arch/powerpc/include/asm/mmu.h | 9 +
> arch/powerpc/include/asm/mmu_context.h | 22 ++
> arch/powerpc/include/asm/pkeys.h | 229 ++++++++++++
> arch/powerpc/include/asm/processor.h | 5 +
> arch/powerpc/include/asm/reg.h | 1 -
> arch/powerpc/include/asm/systbl.h | 3 +
> arch/powerpc/include/asm/unistd.h | 6 +-
> arch/powerpc/include/uapi/asm/elf.h | 1 +
> arch/powerpc/include/uapi/asm/mman.h | 6 +
> arch/powerpc/include/uapi/asm/unistd.h | 3 +
> arch/powerpc/kernel/exceptions-64s.S | 2 +-
> arch/powerpc/kernel/process.c | 7 +
> arch/powerpc/kernel/ptrace.c | 66 ++++
> arch/powerpc/kernel/traps.c | 19 +-
> arch/powerpc/mm/Makefile | 1 +
> arch/powerpc/mm/fault.c | 49 +++-
> arch/powerpc/mm/hash_utils_64.c | 26 ++
> arch/powerpc/mm/mmu_context_book3s64.c | 2 +
> arch/powerpc/mm/pkeys.c | 469 +++++++++++++++++++++++++
> 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 | 16 +-
> include/linux/mm.h | 12 +-
> include/linux/pkeys.h | 5 +
> include/uapi/linux/elf.h | 1 +
> 33 files changed, 1040 insertions(+), 42 deletions(-)
> create mode 100644 arch/powerpc/include/asm/pkeys.h
> create mode 100644 arch/powerpc/mm/pkeys.c
--
Ram Pai
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