From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
Andrey Konovalov <andreyknvl@google.com>
Cc: linux-arm-kernel@lists.infradead.org,
Marco Elver <elver@google.com>,
Elena Petrova <lenaptr@google.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Will Deacon <will.deacon@arm.com>,
Branislav Rankov <Branislav.Rankov@arm.com>,
kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Andrew Morton <akpm@linux-foundation.org>,
Evgenii Stepanov <eugenis@google.com>
Subject: Re: [PATCH v3 29/39] arm64: mte: Switch GCR_EL1 in kernel entry and exit
Date: Fri, 25 Sep 2020 12:50:23 +0100 [thread overview]
Message-ID: <e4624059-1598-17eb-2c64-3e7f26c2a1ba@arm.com> (raw)
In-Reply-To: <20200925113433.GF4846@gaia>
On 9/25/20 12:34 PM, Catalin Marinas wrote:
> On Fri, Sep 25, 2020 at 12:50:36AM +0200, Andrey Konovalov wrote:
>> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
>> index ff34461524d4..c7cc1fdfbd1a 100644
>> --- a/arch/arm64/kernel/entry.S
>> +++ b/arch/arm64/kernel/entry.S
>> @@ -175,6 +175,49 @@ alternative_else_nop_endif
>> #endif
>> .endm
>>
>> + .macro mte_set_gcr, tmp, tmp2
>> +#ifdef CONFIG_ARM64_MTE
>> +alternative_if_not ARM64_MTE
>> + b 1f
>> +alternative_else_nop_endif
>
> You don't need the alternative here. The macro is only invoked in an
> alternative path already (I'd be surprised if it even works, we don't
> handle nested alternatives well).
>
Yes, you are right. I forgot to remove it.
>> + /*
>> + * Calculate and set the exclude mask preserving
>> + * the RRND (bit[16]) setting.
>> + */
>> + mrs_s \tmp2, SYS_GCR_EL1
>> + bfi \tmp2, \tmp, #0, #16
>> + msr_s SYS_GCR_EL1, \tmp2
>> + isb
>> +1:
>> +#endif
>> + .endm
>> +
>> + .macro mte_set_kernel_gcr, tsk, tmp, tmp2
>
> What's the point of a 'tsk' argument here?
>
It is unused. I kept the interface same in between kernel and user.
I can either add a comment or remove it. Which one do you prefer?
>> +#ifdef CONFIG_KASAN_HW_TAGS
>> +#ifdef CONFIG_ARM64_MTE
>
> Does KASAN_HW_TAGS depend on ARM64_MTE already? Just to avoid too may
> ifdefs. Otherwise, you can always write it as:
>
> #if defined(CONFIG_KASAN_HW_TAGS) && defined(CONFIG_ARM64_MTE)
>
> to save two lines (and its easier to read).
>
It is indeed. I forgot to remove CONFIG_ARM64_MTE.
>> +alternative_if_not ARM64_MTE
>> + b 1f
>> +alternative_else_nop_endif
>> + ldr_l \tmp, gcr_kernel_excl
>> +
>> + mte_set_gcr \tmp, \tmp2
>> +1:
>> +#endif
>> +#endif
>> + .endm
>> +
>> + .macro mte_set_user_gcr, tsk, tmp, tmp2
>> +#ifdef CONFIG_ARM64_MTE
>> +alternative_if_not ARM64_MTE
>> + b 1f
>> +alternative_else_nop_endif
>> + ldr \tmp, [\tsk, #THREAD_GCR_EL1_USER]
>> +
>> + mte_set_gcr \tmp, \tmp2
>> +1:
>> +#endif
>> + .endm
>> +
>> .macro kernel_entry, el, regsize = 64
>> .if \regsize == 32
>> mov w0, w0 // zero upper 32 bits of x0
>> @@ -214,6 +257,8 @@ alternative_else_nop_endif
>>
>> ptrauth_keys_install_kernel tsk, x20, x22, x23
>>
>> + mte_set_kernel_gcr tsk, x22, x23
>> +
>> scs_load tsk, x20
>> .else
>> add x21, sp, #S_FRAME_SIZE
>> @@ -332,6 +377,8 @@ alternative_else_nop_endif
>> /* No kernel C function calls after this as user keys are set. */
>> ptrauth_keys_install_user tsk, x0, x1, x2
>>
>> + mte_set_user_gcr tsk, x0, x1
>> +
>> apply_ssbd 0, x0, x1
>> .endif
>>
>> diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
>> index 393d0c794be4..c3b4f056fc54 100644
>> --- a/arch/arm64/kernel/mte.c
>> +++ b/arch/arm64/kernel/mte.c
>> @@ -22,6 +22,8 @@
>> #include <asm/ptrace.h>
>> #include <asm/sysreg.h>
>>
>> +u64 gcr_kernel_excl __ro_after_init;
>> +
>> static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap)
>> {
>> pte_t old_pte = READ_ONCE(*ptep);
>> @@ -116,6 +118,13 @@ void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
>> return ptr;
>> }
>>
>> +void mte_init_tags(u64 max_tag)
>> +{
>> + u64 incl = GENMASK(max_tag & MTE_TAG_MAX, 0);
>> +
>> + gcr_kernel_excl = ~incl & SYS_GCR_EL1_EXCL_MASK;
>> +}
>> +
>> static void update_sctlr_el1_tcf0(u64 tcf0)
>> {
>> /* ISB required for the kernel uaccess routines */
>> @@ -151,7 +160,11 @@ static void update_gcr_el1_excl(u64 excl)
>> static void set_gcr_el1_excl(u64 excl)
>> {
>> current->thread.gcr_user_excl = excl;
>> - update_gcr_el1_excl(excl);
>> +
>> + /*
>> + * SYS_GCR_EL1 will be set to current->thread.gcr_user_incl value
> ^^^^^^^^^^^^^
> That's gcr_user_excl now.
>
>> + * by mte_restore_gcr() in kernel_exit,
>
> I don't think mte_restore_gcr is still around in this patch.
>
This comment requires updating. I missed it.
--
Regards,
Vincenzo
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next prev parent reply other threads:[~2020-09-25 11:49 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-24 22:50 [PATCH v3 00/39] kasan: add hardware tag-based mode for arm64 Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 01/39] kasan: drop unnecessary GPL text from comment headers Andrey Konovalov
2020-10-01 17:18 ` elver
2020-09-24 22:50 ` [PATCH v3 02/39] kasan: KASAN_VMALLOC depends on KASAN_GENERIC Andrey Konovalov
2020-10-01 17:19 ` elver
2020-09-24 22:50 ` [PATCH v3 03/39] kasan: group vmalloc code Andrey Konovalov
2020-10-01 17:27 ` elver
2020-09-24 22:50 ` [PATCH v3 04/39] kasan: shadow declarations only for software modes Andrey Konovalov
2020-10-01 17:29 ` elver
2020-09-24 22:50 ` [PATCH v3 05/39] kasan: rename (un)poison_shadow to (un)poison_memory Andrey Konovalov
2020-10-01 17:29 ` elver
2020-09-24 22:50 ` [PATCH v3 06/39] kasan: rename KASAN_SHADOW_* to KASAN_GRANULE_* Andrey Konovalov
2020-10-01 17:30 ` elver
2020-09-24 22:50 ` [PATCH v3 07/39] kasan: only build init.c for software modes Andrey Konovalov
2020-10-01 17:31 ` elver
2020-09-24 22:50 ` [PATCH v3 08/39] kasan: split out shadow.c from common.c Andrey Konovalov
2020-10-01 17:32 ` elver
2020-09-24 22:50 ` [PATCH v3 09/39] kasan: define KASAN_GRANULE_PAGE Andrey Konovalov
2020-10-01 17:33 ` elver
2020-09-24 22:50 ` [PATCH v3 10/39] kasan: rename report and tags files Andrey Konovalov
2020-10-01 17:36 ` elver
2020-09-24 22:50 ` [PATCH v3 11/39] kasan: don't duplicate config dependencies Andrey Konovalov
2020-10-01 17:39 ` elver
2020-10-01 21:54 ` Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 12/39] kasan: hide invalid free check implementation Andrey Konovalov
2020-10-01 17:41 ` elver
2020-09-24 22:50 ` [PATCH v3 13/39] kasan: decode stack frame only with KASAN_STACK_ENABLE Andrey Konovalov
2020-10-01 17:43 ` elver
2020-09-24 22:50 ` [PATCH v3 14/39] kasan, arm64: only init shadow for software modes Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 15/39] kasan, arm64: only use kasan_depth " Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 16/39] kasan: rename addr_has_shadow to addr_has_metadata Andrey Konovalov
2020-10-01 17:45 ` elver
2020-09-24 22:50 ` [PATCH v3 17/39] kasan: rename print_shadow_for_address to print_memory_metadata Andrey Konovalov
2020-10-01 17:45 ` elver
2020-09-24 22:50 ` [PATCH v3 18/39] kasan: kasan_non_canonical_hook only for software modes Andrey Konovalov
2020-10-01 17:47 ` elver
2020-09-24 22:50 ` [PATCH v3 19/39] kasan: rename SHADOW layout macros to META Andrey Konovalov
2020-10-01 17:48 ` elver
2020-09-24 22:50 ` [PATCH v3 20/39] kasan: separate metadata_fetch_row for each mode Andrey Konovalov
2020-10-01 17:54 ` elver
2020-10-01 21:56 ` Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 21/39] kasan: don't allow SW_TAGS with ARM64_MTE Andrey Konovalov
2020-10-01 17:55 ` elver
2020-10-01 21:57 ` Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 22/39] kasan: introduce CONFIG_KASAN_HW_TAGS Andrey Konovalov
2020-10-01 17:57 ` elver
2020-09-24 22:50 ` [PATCH v3 23/39] arm64: Enable armv8.5-a asm-arch option Andrey Konovalov
2020-09-25 10:16 ` Catalin Marinas
2020-09-24 22:50 ` [PATCH v3 24/39] arm64: mte: Add in-kernel MTE helpers Andrey Konovalov
2020-09-25 10:15 ` Catalin Marinas
2020-09-25 11:28 ` Vincenzo Frascino
2020-09-25 12:50 ` Catalin Marinas
2020-09-25 13:36 ` Vincenzo Frascino
2020-09-24 22:50 ` [PATCH v3 25/39] arm64: kasan: Add arch layer for memory tagging helpers Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 26/39] arm64: mte: Add in-kernel tag fault handler Andrey Konovalov
2020-09-25 10:49 ` Catalin Marinas
2020-09-25 11:26 ` Andrey Konovalov
2020-09-25 11:47 ` Catalin Marinas
2020-09-25 11:52 ` Andrey Konovalov
2020-09-25 12:35 ` Catalin Marinas
2020-09-25 12:35 ` Catalin Marinas
2020-09-24 22:50 ` [PATCH v3 27/39] arm64: kasan: Enable in-kernel MTE Andrey Konovalov
2020-09-25 11:14 ` Catalin Marinas
2020-09-24 22:50 ` [PATCH v3 28/39] arm64: mte: Convert gcr_user into an exclude mask Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 29/39] arm64: mte: Switch GCR_EL1 in kernel entry and exit Andrey Konovalov
2020-09-25 11:34 ` Catalin Marinas
2020-09-25 11:50 ` Vincenzo Frascino [this message]
2020-09-25 12:38 ` Catalin Marinas
2020-09-24 22:50 ` [PATCH v3 30/39] arm64: kasan: Enable TBI EL1 Andrey Konovalov
2020-09-25 11:37 ` Catalin Marinas
2020-09-25 11:47 ` Vincenzo Frascino
2020-09-24 22:50 ` [PATCH v3 31/39] arm64: kasan: Align allocations for HW_TAGS Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 32/39] kasan: define KASAN_GRANULE_SIZE " Andrey Konovalov
2020-10-01 17:58 ` elver
2020-10-01 21:59 ` Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 33/39] kasan, x86, s390: update undef CONFIG_KASAN Andrey Konovalov
2020-10-01 17:59 ` elver
2020-09-24 22:50 ` [PATCH v3 34/39] kasan, arm64: expand CONFIG_KASAN checks Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 35/39] kasan, arm64: implement HW_TAGS runtime Andrey Konovalov
2020-10-01 18:00 ` elver
2020-09-24 22:50 ` [PATCH v3 36/39] kasan, arm64: print report from tag fault handler Andrey Konovalov
2020-09-25 11:39 ` Catalin Marinas
2020-09-24 22:50 ` [PATCH v3 37/39] kasan, slub: reset tags when accessing metadata Andrey Konovalov
2020-10-01 18:03 ` elver
2020-10-01 22:00 ` Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 38/39] kasan, arm64: enable CONFIG_KASAN_HW_TAGS Andrey Konovalov
2020-09-24 22:50 ` [PATCH v3 39/39] kasan: add documentation for hardware tag-based mode Andrey Konovalov
2020-10-01 18:03 ` elver
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