From: Catalin Marinas <catalin.marinas@arm.com>
To: 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>,
Evgenii Stepanov <eugenis@google.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH 21/35] arm64: mte: Add in-kernel tag fault handler
Date: Thu, 27 Aug 2020 10:54:29 +0100 [thread overview]
Message-ID: <20200827095429.GC29264@gaia> (raw)
In-Reply-To: <f173aacd755e4644485c551198549ac52d1eb650.1597425745.git.andreyknvl@google.com>
On Fri, Aug 14, 2020 at 07:27:03PM +0200, Andrey Konovalov wrote:
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index 5e832b3387f1..c62c8ba85c0e 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -33,6 +33,7 @@
> #include <asm/debug-monitors.h>
> #include <asm/esr.h>
> #include <asm/kprobes.h>
> +#include <asm/mte.h>
> #include <asm/processor.h>
> #include <asm/sysreg.h>
> #include <asm/system_misc.h>
> @@ -222,6 +223,20 @@ int ptep_set_access_flags(struct vm_area_struct *vma,
> return 1;
> }
>
> +static bool is_el1_mte_sync_tag_check_fault(unsigned int esr)
> +{
> + unsigned int ec = ESR_ELx_EC(esr);
> + unsigned int fsc = esr & ESR_ELx_FSC;
> +
> + if (ec != ESR_ELx_EC_DABT_CUR)
> + return false;
> +
> + if (fsc == ESR_ELx_FSC_MTE)
> + return true;
> +
> + return false;
> +}
> +
> static bool is_el1_instruction_abort(unsigned int esr)
> {
> return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR;
> @@ -294,6 +309,18 @@ static void die_kernel_fault(const char *msg, unsigned long addr,
> do_exit(SIGKILL);
> }
>
> +static void report_tag_fault(unsigned long addr, unsigned int esr,
> + struct pt_regs *regs)
> +{
> + bool is_write = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0;
> +
> + pr_alert("Memory Tagging Extension Fault in %pS\n", (void *)regs->pc);
> + pr_alert(" %s at address %lx\n", is_write ? "Write" : "Read", addr);
> + pr_alert(" Pointer tag: [%02x], memory tag: [%02x]\n",
> + mte_get_ptr_tag(addr),
> + mte_get_mem_tag((void *)addr));
> +}
> +
> static void __do_kernel_fault(unsigned long addr, unsigned int esr,
> struct pt_regs *regs)
> {
> @@ -317,12 +344,16 @@ static void __do_kernel_fault(unsigned long addr, unsigned int esr,
> msg = "execute from non-executable memory";
> else
> msg = "read from unreadable memory";
> + } else if (is_el1_mte_sync_tag_check_fault(esr)) {
> + report_tag_fault(addr, esr, regs);
> + msg = "memory tagging extension fault";
IIUC, that's dead code. See my comment below on do_tag_check_fault().
> } else if (addr < PAGE_SIZE) {
> msg = "NULL pointer dereference";
> } else {
> msg = "paging request";
> }
>
> +
Unnecessary empty line.
> die_kernel_fault(msg, addr, esr, regs);
> }
>
> @@ -658,10 +689,27 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
> return 0;
> }
>
> +static int do_tag_recovery(unsigned long addr, unsigned int esr,
> + struct pt_regs *regs)
> +{
> + report_tag_fault(addr, esr, regs);
> +
> + /* Skip over the faulting instruction and continue: */
> + arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
Ooooh, do we expect the kernel to still behave correctly after this? I
thought the recovery means disabling tag checking altogether and
restarting the instruction rather than skipping over it. We only skip if
we emulated it.
> +
> + return 0;
> +}
> +
> +
> static int do_tag_check_fault(unsigned long addr, unsigned int esr,
> struct pt_regs *regs)
> {
> - do_bad_area(addr, esr, regs);
> + /* The tag check fault (TCF) is per TTBR */
> + if (is_ttbr0_addr(addr))
> + do_bad_area(addr, esr, regs);
> + else
> + do_tag_recovery(addr, esr, regs);
So we never invoke __do_kernel_fault() for a synchronous tag check in
the kernel. What's with all the is_el1_mte_sync_tag_check_fault() check
above?
--
Catalin
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next prev parent reply other threads:[~2020-08-27 9:55 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-14 17:26 [PATCH 00/35] kasan: add hardware tag-based mode for arm64 Andrey Konovalov
2020-08-14 17:26 ` [PATCH 01/35] kasan: KASAN_VMALLOC depends on KASAN_GENERIC Andrey Konovalov
2020-08-14 17:26 ` [PATCH 02/35] kasan: group vmalloc code Andrey Konovalov
2020-08-14 17:26 ` [PATCH 03/35] kasan: shadow declarations only for software modes Andrey Konovalov
2020-09-18 14:55 ` Marco Elver
2020-09-18 14:56 ` Andrey Konovalov
2020-08-14 17:26 ` [PATCH 04/35] kasan: rename (un)poison_shadow to (un)poison_memory Andrey Konovalov
2020-08-14 17:26 ` [PATCH 05/35] kasan: rename KASAN_SHADOW_* to KASAN_GRANULE_* Andrey Konovalov
2020-08-14 17:26 ` [PATCH 06/35] kasan: only build init.c for software modes Andrey Konovalov
2020-08-14 17:26 ` [PATCH 07/35] kasan: split out shadow.c from common.c Andrey Konovalov
2020-08-14 17:26 ` [PATCH 08/35] kasan: rename generic/tags_report.c files Andrey Konovalov
2020-08-14 17:26 ` [PATCH 09/35] kasan: don't duplicate config dependencies Andrey Konovalov
2020-08-14 17:26 ` [PATCH 10/35] kasan: hide invalid free check implementation Andrey Konovalov
2020-08-14 17:26 ` [PATCH 11/35] kasan: decode stack frame only with KASAN_STACK_ENABLE Andrey Konovalov
2020-08-14 17:26 ` [PATCH 12/35] kasan, arm64: only init shadow for software modes Andrey Konovalov
2020-08-14 17:26 ` [PATCH 13/35] kasan, arm64: only use kasan_depth " Andrey Konovalov
2020-08-14 17:26 ` [PATCH 14/35] kasan: rename addr_has_shadow to addr_has_metadata Andrey Konovalov
2020-08-14 17:26 ` [PATCH 15/35] kasan: rename print_shadow_for_address to print_memory_metadata Andrey Konovalov
2020-08-14 17:26 ` [PATCH 16/35] kasan: kasan_non_canonical_hook only for software modes Andrey Konovalov
2020-08-14 17:26 ` [PATCH 17/35] kasan: rename SHADOW layout macros to META Andrey Konovalov
2020-08-14 17:27 ` [PATCH 18/35] kasan: separate metadata_fetch_row for each mode Andrey Konovalov
2020-08-14 17:27 ` [PATCH 19/35] kasan: don't allow SW_TAGS with ARM64_MTE Andrey Konovalov
2020-08-27 8:04 ` Catalin Marinas
2020-08-27 9:54 ` Vincenzo Frascino
2020-08-27 12:02 ` Andrey Konovalov
2020-08-14 17:27 ` [PATCH 20/35] arm64: mte: Add in-kernel MTE helpers Andrey Konovalov
2020-08-27 9:38 ` Catalin Marinas
2020-08-27 10:31 ` Vincenzo Frascino
2020-08-27 11:10 ` Catalin Marinas
2020-08-27 11:24 ` Vincenzo Frascino
2020-08-27 12:46 ` Andrey Konovalov
2020-09-08 13:23 ` Andrey Konovalov
2020-09-08 14:50 ` Catalin Marinas
2020-08-14 17:27 ` [PATCH 21/35] arm64: mte: Add in-kernel tag fault handler Andrey Konovalov
2020-08-27 9:54 ` Catalin Marinas [this message]
2020-08-27 10:44 ` Vincenzo Frascino
2020-08-27 12:31 ` Andrey Konovalov
2020-08-27 13:10 ` Catalin Marinas
2020-08-27 13:34 ` Andrey Konovalov
2020-08-27 14:56 ` Catalin Marinas
2020-08-27 19:14 ` Evgenii Stepanov
2020-08-28 9:56 ` Catalin Marinas
2020-08-14 17:27 ` [PATCH 22/35] arm64: mte: Enable in-kernel MTE Andrey Konovalov
2020-08-27 10:01 ` Catalin Marinas
2020-08-27 10:46 ` Vincenzo Frascino
2020-09-08 14:39 ` Andrey Konovalov
2020-09-08 14:52 ` Catalin Marinas
2020-08-14 17:27 ` [PATCH 23/35] arm64: mte: Convert gcr_user into an exclude mask Andrey Konovalov
2020-08-14 17:27 ` [PATCH 24/35] arm64: mte: Switch GCR_EL1 in kernel entry and exit Andrey Konovalov
2020-08-27 10:38 ` Catalin Marinas
2020-08-27 10:56 ` Vincenzo Frascino
2020-08-27 12:16 ` Catalin Marinas
2020-09-08 14:02 ` Andrey Konovalov
2020-09-08 14:53 ` Andrey Konovalov
2020-09-08 15:39 ` Catalin Marinas
2020-09-08 19:41 ` Derrick McKee
2020-09-08 13:58 ` Andrey Konovalov
2020-09-08 15:16 ` Catalin Marinas
2020-08-14 17:27 ` [PATCH 25/35] kasan: introduce CONFIG_KASAN_HW_TAGS Andrey Konovalov
2020-08-27 11:33 ` Vincenzo Frascino
2020-08-27 12:22 ` Andrey Konovalov
2020-08-14 17:27 ` [PATCH 26/35] kasan, arm64: Enable TBI EL1 Andrey Konovalov
2020-08-27 10:40 ` Catalin Marinas
2020-08-27 11:05 ` Vincenzo Frascino
2020-08-27 11:13 ` Catalin Marinas
2020-08-27 11:17 ` Vincenzo Frascino
2020-08-27 12:43 ` Andrey Konovalov
2020-08-27 13:45 ` Vincenzo Frascino
2020-08-27 14:36 ` Andrey Konovalov
2020-09-08 13:18 ` Andrey Konovalov
2020-09-08 14:06 ` Catalin Marinas
2020-09-08 14:12 ` Andrey Konovalov
2020-09-08 14:41 ` Catalin Marinas
2020-08-14 17:27 ` [PATCH 27/35] kasan, arm64: align allocations for HW_TAGS Andrey Konovalov
2020-08-14 17:27 ` [PATCH 28/35] kasan: define KASAN_GRANULE_SIZE " Andrey Konovalov
2020-08-27 10:41 ` Catalin Marinas
2020-08-27 11:07 ` Vincenzo Frascino
2020-08-27 12:05 ` Andrey Konovalov
2020-08-14 17:27 ` [PATCH 29/35] kasan, x86, s390: update undef CONFIG_KASAN Andrey Konovalov
2020-08-14 17:27 ` [PATCH 30/35] kasan, arm64: expand CONFIG_KASAN checks Andrey Konovalov
2020-08-14 17:27 ` [PATCH 31/35] kasan, arm64: implement HW_TAGS runtime Andrey Konovalov
2020-08-27 10:45 ` Catalin Marinas
2020-08-27 11:35 ` Vincenzo Frascino
2020-08-27 12:37 ` Andrey Konovalov
2020-08-14 17:27 ` [PATCH 32/35] kasan, arm64: print report from tag fault handler Andrey Konovalov
2020-08-27 10:48 ` Catalin Marinas
2020-08-27 12:11 ` Vincenzo Frascino
2020-08-27 12:34 ` Andrey Konovalov
2020-08-27 14:21 ` Catalin Marinas
2020-08-14 17:27 ` [PATCH 33/35] kasan, slub: reset tags when accessing metadata Andrey Konovalov
2020-08-14 17:27 ` [PATCH 34/35] kasan, arm64: enable CONFIG_KASAN_HW_TAGS Andrey Konovalov
2020-08-14 17:27 ` [PATCH 35/35] kasan: add documentation for hardware tag-based mode Andrey Konovalov
2020-08-28 11:12 ` Marco Elver
2020-08-28 12:28 ` Andrey Konovalov
2020-09-14 19:06 ` [PATCH 00/35] kasan: add hardware tag-based mode for arm64 Derrick McKee
2020-09-14 20:04 ` Andrey Konovalov
2020-09-14 21:36 ` Derrick McKee
2020-09-14 22:41 ` Derrick McKee
2020-09-14 22:50 ` Andrey Konovalov
2020-09-15 9:46 ` Derrick McKee
2020-09-15 17:51 ` Derrick McKee
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