Hi Khalid, On Fri, Mar 4, 2016 at 4:42 AM, Khalid Aziz <khalid.aziz@xxxxxxxxxx> wrote: > On 03/02/2016 06:33 PM, Julian Calaby wrote: >> >> Hi Khalid, >> >> A couple of other comments: >> >> On Thu, Mar 3, 2016 at 5:54 AM, Khalid Aziz <khalid.aziz@xxxxxxxxxx> >> wrote: >>> >>> >>> Enable Application Data Integrity (ADI) support in the sparc >>> kernel for applications to use ADI in userspace. ADI is a new >>> feature supported on sparc M7 and newer processors. ADI is supported >>> for data fetches only and not instruction fetches. This patch adds >>> prctl commands to enable and disable ADI (TSTATE.mcde), return ADI >>> parameters to userspace, enable/disable MCD (Memory Corruption >>> Detection) on selected memory ranges and enable TTE.mcd in PTEs. It >>> also adds handlers for all traps related to MCD. ADI is not enabled >>> by default for any task and a task must explicitly enable ADI >>> (TSTATE.mcde), turn MCD on on a memory range and set version tag >>> for ADI to be effective for the task. This patch adds support for >>> ADI for hugepages only. Addresses passed into system calls must be >>> non-ADI tagged addresses. >>> >>> Signed-off-by: Khalid Aziz <khalid.aziz@xxxxxxxxxx> >>> --- >>> NOTES: ADI is a new feature added to M7 processor to allow hardware >>> to catch rogue accesses to memory. An app can enable ADI on >>> its data pages, set version tags on them and use versioned >>> addresses (bits 63-60 of the address contain a version tag) >>> to access the data pages. If a rogue app attempts to access >>> ADI enabled data pages, its access is blocked and processor >>> generates an exception. Enabling this functionality for all >>> data pages of an app requires adding infrastructure to save >>> version tags for any data pages that get swapped out and >>> restoring those tags when pages are swapped back in. In this >>> first implementation I am enabling ADI for hugepages only >>> since these pages are locked in memory and hence avoid the >>> issue of saving and restoring tags. Once this core functionality >>> is stable, ADI for other memory pages can be enabled more >>> easily. >>> >>> Documentation/prctl/sparc_adi.txt | 62 ++++++++++ >>> Documentation/sparc/adi.txt | 206 >>> +++++++++++++++++++++++++++++++ >>> arch/sparc/Kconfig | 12 ++ >>> arch/sparc/include/asm/hugetlb.h | 14 +++ >>> arch/sparc/include/asm/hypervisor.h | 2 + >>> arch/sparc/include/asm/mmu_64.h | 1 + >>> arch/sparc/include/asm/pgtable_64.h | 15 +++ >>> arch/sparc/include/asm/processor_64.h | 19 +++ >>> arch/sparc/include/asm/ttable.h | 10 ++ >>> arch/sparc/include/uapi/asm/asi.h | 3 + >>> arch/sparc/include/uapi/asm/pstate.h | 10 ++ >>> arch/sparc/kernel/entry.h | 3 + >>> arch/sparc/kernel/head_64.S | 1 + >>> arch/sparc/kernel/mdesc.c | 81 +++++++++++++ >>> arch/sparc/kernel/process_64.c | 221 >>> ++++++++++++++++++++++++++++++++++ >>> arch/sparc/kernel/sun4v_mcd.S | 16 +++ >>> arch/sparc/kernel/traps_64.c | 96 ++++++++++++++- >>> arch/sparc/kernel/ttable_64.S | 6 +- >>> include/linux/mm.h | 2 + >>> include/uapi/asm-generic/siginfo.h | 5 +- >>> include/uapi/linux/prctl.h | 16 +++ >>> kernel/sys.c | 30 +++++ >>> 22 files changed, 825 insertions(+), 6 deletions(-) >>> create mode 100644 Documentation/prctl/sparc_adi.txt >>> create mode 100644 Documentation/sparc/adi.txt >>> create mode 100644 arch/sparc/kernel/sun4v_mcd.S >>> >>> diff --git a/arch/sparc/include/asm/pgtable_64.h >>> b/arch/sparc/include/asm/pgtable_64.h >>> index 131d36f..cddea30 100644 >>> --- a/arch/sparc/include/asm/pgtable_64.h >>> +++ b/arch/sparc/include/asm/pgtable_64.h >>> @@ -162,6 +162,9 @@ bool kern_addr_valid(unsigned long addr); >>> #define _PAGE_E_4V _AC(0x0000000000000800,UL) /* side-Effect >>> */ >>> #define _PAGE_CP_4V _AC(0x0000000000000400,UL) /* Cacheable in >>> P-Cache */ >>> #define _PAGE_CV_4V _AC(0x0000000000000200,UL) /* Cacheable in >>> V-Cache */ >>> +/* Bit 9 is used to enable MCD corruption detection instead on M7 >>> + */ >>> +#define _PAGE_MCD_4V _AC(0x0000000000000200,UL) /* Memory Corruption >>> */ >> >> >> I'm not sure that everywhere _PAGE_CV_4V is used is guarded against >> setting it on M7, could someone who knows the code better than I do >> please check that? It looks like the tests around it's use are >> essentially "is it sun4v". >> >> I'm probably being paranoid, but reused values like this make me worry. >> > > I took care of this issue in an earlier patch (commit > 494e5b6faeda1d1e830a13e10b3c7bc323f35d97 - "sparc: Resolve conflict between > sparc v9 and M7 on usage of bit 9 of TTE"), so I think we are ok here. Ah, I remember those changes, however I didn't recall which processor they were for, so that's awesome. >>> #define _PAGE_P_4V _AC(0x0000000000000100,UL) /* Privileged Page >>> */ >>> #define _PAGE_EXEC_4V _AC(0x0000000000000080,UL) /* Executable Page >>> */ >>> #define _PAGE_W_4V _AC(0x0000000000000040,UL) /* Writable >>> */ >>> diff --git a/arch/sparc/include/uapi/asm/pstate.h >>> b/arch/sparc/include/uapi/asm/pstate.h >>> index cf832e1..d0521db 100644 >>> --- a/arch/sparc/include/uapi/asm/pstate.h >>> +++ b/arch/sparc/include/uapi/asm/pstate.h >>> @@ -10,7 +10,12 @@ >>> * >>> ----------------------------------------------------------------------- >>> * 63 12 11 10 9 8 7 6 5 4 3 2 1 >>> 0 >>> */ >>> +/* IG on V9 conflicts with MCDE on M7. PSTATE_MCDE will only be used on >>> + * processors that support ADI which do not use IG, hence there is no >>> + * functional conflict >>> + */ >>> #define PSTATE_IG _AC(0x0000000000000800,UL) /* Interrupt Globals. >>> */ >>> +#define PSTATE_MCDE _AC(0x0000000000000800,UL) /* MCD Enable >>> */ >> >> >> Again, I can't tell if the code that uses PSTATE_IG is guarded against >> use on M7. Could someone else please check? It's used in cherrs.S >> which appears to be Cheetah specific, so that's not a problem, however >> it's also used in ultra.S in xcall_sync_tick which might get patched >> out however I don't know the code well enough to be certain. I'm also >> guessing that as this file is in include/uapi, userspace could use it >> for something. > > > My understanding of the code in ultra.S is xcall_sync_tick doe snot get > called on sun4v, so PSTATE_IG will not get set unintentionally on M7. > include/uapi is an interesting thought. PSTATE is a privileged register, so > userspace can not write to it directly without using a system call. I don't > think that is an issue here. Is it something userspace would interpret then? I guess any software making use of the PSTATE or TSTATE registers would have to handle any processor differences itself. Thanks for explaining this! -- Julian Calaby Email: julian.calaby@xxxxxxxxx Profile: http://www.google.com/profiles/julian.calaby/ -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
