From: Andrey Konovalov <andreyknvl@google.com>
To: Dmitry Vyukov <dvyukov@google.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
kasan-dev@googlegroups.com
Cc: Marco Elver <elver@google.com>,
Elena Petrova <lenaptr@google.com>,
Andrey Konovalov <andreyknvl@google.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Will Deacon <will.deacon@arm.com>,
Branislav Rankov <Branislav.Rankov@arm.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Alexander Potapenko <glider@google.com>,
linux-arm-kernel@lists.infradead.org,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Andrew Morton <akpm@linux-foundation.org>,
Evgenii Stepanov <eugenis@google.com>
Subject: [PATCH v2 27/37] arm64: mte: Switch GCR_EL1 in kernel entry and exit
Date: Tue, 15 Sep 2020 23:16:09 +0200 [thread overview]
Message-ID: <c801517c8c6c0b14ac2f5d9e189ff86fdbf1d495.1600204505.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1600204505.git.andreyknvl@google.com>
From: Vincenzo Frascino <vincenzo.frascino@arm.com>
When MTE is present, the GCR_EL1 register contains the tags mask that
allows to exclude tags from the random generation via the IRG instruction.
With the introduction of the new Tag-Based KASAN API that provides a
mechanism to reserve tags for special reasons, the MTE implementation
has to make sure that the GCR_EL1 setting for the kernel does not affect
the userspace processes and viceversa.
Save and restore the kernel/user mask in GCR_EL1 in kernel entry and exit.
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
Change-Id: I0081cba5ace27a9111bebb239075c9a466af4c84
---
arch/arm64/include/asm/mte-helpers.h | 6 ++++++
arch/arm64/include/asm/mte.h | 2 ++
arch/arm64/kernel/asm-offsets.c | 3 +++
arch/arm64/kernel/cpufeature.c | 3 +++
arch/arm64/kernel/entry.S | 26 ++++++++++++++++++++++++++
arch/arm64/kernel/mte.c | 19 ++++++++++++++++---
6 files changed, 56 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/include/asm/mte-helpers.h b/arch/arm64/include/asm/mte-helpers.h
index 5dc2d443851b..60a292fc747c 100644
--- a/arch/arm64/include/asm/mte-helpers.h
+++ b/arch/arm64/include/asm/mte-helpers.h
@@ -25,6 +25,8 @@ u8 mte_get_mem_tag(void *addr);
u8 mte_get_random_tag(void);
void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag);
+void mte_init_tags(u64 max_tag);
+
#else /* CONFIG_ARM64_MTE */
#define mte_get_ptr_tag(ptr) 0xFF
@@ -41,6 +43,10 @@ static inline void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
return addr;
}
+static inline void mte_init_tags(u64 max_tag)
+{
+}
+
#endif /* CONFIG_ARM64_MTE */
#endif /* __ASSEMBLY__ */
diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index 82cd7c89edec..3142a2de51ae 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -15,6 +15,8 @@
#include <asm/pgtable-types.h>
+extern u64 gcr_kernel_excl;
+
void mte_clear_page_tags(void *addr);
unsigned long mte_copy_tags_from_user(void *to, const void __user *from,
unsigned long n);
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 7d32fc959b1a..dfe6ed8446ac 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -47,6 +47,9 @@ int main(void)
#ifdef CONFIG_ARM64_PTR_AUTH
DEFINE(THREAD_KEYS_USER, offsetof(struct task_struct, thread.keys_user));
DEFINE(THREAD_KEYS_KERNEL, offsetof(struct task_struct, thread.keys_kernel));
+#endif
+#ifdef CONFIG_ARM64_MTE
+ DEFINE(THREAD_GCR_EL1_USER, offsetof(struct task_struct, thread.gcr_user_excl));
#endif
BLANK();
DEFINE(S_X0, offsetof(struct pt_regs, regs[0]));
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index eca06b8c74db..3602ac45d093 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1721,6 +1721,9 @@ static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap)
/* Enable in-kernel MTE only if KASAN_HW_TAGS is enabled */
if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) {
+ /* Enable the kernel exclude mask for random tags generation */
+ write_sysreg_s((SYS_GCR_EL1_RRND | gcr_kernel_excl), SYS_GCR_EL1);
+
/* Enable MTE Sync Mode for EL1 */
sysreg_clear_set(sctlr_el1, SCTLR_ELx_TCF_MASK, SCTLR_ELx_TCF_SYNC);
isb();
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index ff34461524d4..79a6848840bd 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -175,6 +175,28 @@ alternative_else_nop_endif
#endif
.endm
+ .macro mte_restore_gcr, el, tsk, tmp, tmp2
+#ifdef CONFIG_ARM64_MTE
+alternative_if_not ARM64_MTE
+ b 1f
+alternative_else_nop_endif
+ .if \el == 0
+ ldr \tmp, [\tsk, #THREAD_GCR_EL1_USER]
+ .else
+ ldr_l \tmp, gcr_kernel_excl
+ .endif
+ /*
+ * 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 kernel_entry, el, regsize = 64
.if \regsize == 32
mov w0, w0 // zero upper 32 bits of x0
@@ -214,6 +236,8 @@ alternative_else_nop_endif
ptrauth_keys_install_kernel tsk, x20, x22, x23
+ mte_restore_gcr 1, tsk, x22, x23
+
scs_load tsk, x20
.else
add x21, sp, #S_FRAME_SIZE
@@ -332,6 +356,8 @@ 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_restore_gcr 0, tsk, x0, x1
+
apply_ssbd 0, x0, x1
.endif
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index 858e75cfcaa0..1c7d963b5038 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -18,10 +18,13 @@
#include <asm/barrier.h>
#include <asm/cpufeature.h>
+#include <asm/kprobes.h>
#include <asm/mte.h>
#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);
@@ -120,6 +123,13 @@ 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 */
@@ -155,7 +165,11 @@ 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
+ * by mte_restore_gcr() in kernel_exit,
+ */
}
void flush_mte_state(void)
@@ -181,7 +195,6 @@ void mte_thread_switch(struct task_struct *next)
/* avoid expensive SCTLR_EL1 accesses if no change */
if (current->thread.sctlr_tcf0 != next->thread.sctlr_tcf0)
update_sctlr_el1_tcf0(next->thread.sctlr_tcf0);
- update_gcr_el1_excl(next->thread.gcr_user_excl);
}
void mte_suspend_exit(void)
@@ -189,7 +202,7 @@ void mte_suspend_exit(void)
if (!system_supports_mte())
return;
- update_gcr_el1_excl(current->thread.gcr_user_excl);
+ update_gcr_el1_excl(gcr_kernel_excl);
}
long set_mte_ctrl(struct task_struct *task, unsigned long arg)
--
2.28.0.618.gf4bc123cb7-goog
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next prev parent reply other threads:[~2020-09-15 22:32 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 21:15 [PATCH v2 00/37] kasan: add hardware tag-based mode for arm64 Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 01/37] kasan: KASAN_VMALLOC depends on KASAN_GENERIC Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 02/37] kasan: group vmalloc code Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 03/37] kasan: shadow declarations only for software modes Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 04/37] kasan: rename (un)poison_shadow to (un)poison_memory Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 05/37] kasan: rename KASAN_SHADOW_* to KASAN_GRANULE_* Andrey Konovalov
2020-09-18 8:04 ` Alexander Potapenko
2020-09-18 10:42 ` Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 06/37] kasan: only build init.c for software modes Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 07/37] kasan: split out shadow.c from common.c Andrey Konovalov
2020-09-18 8:17 ` Alexander Potapenko
2020-09-18 10:39 ` Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 08/37] kasan: rename generic/tags_report.c files Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 09/37] kasan: don't duplicate config dependencies Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 10/37] kasan: hide invalid free check implementation Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 11/37] kasan: decode stack frame only with KASAN_STACK_ENABLE Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 12/37] kasan, arm64: only init shadow for software modes Andrey Konovalov
2020-09-17 17:05 ` Catalin Marinas
2020-09-15 21:15 ` [PATCH v2 13/37] kasan, arm64: only use kasan_depth " Andrey Konovalov
2020-09-17 17:05 ` Catalin Marinas
2020-09-15 21:15 ` [PATCH v2 14/37] kasan: rename addr_has_shadow to addr_has_metadata Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 15/37] kasan: rename print_shadow_for_address to print_memory_metadata Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 16/37] kasan: kasan_non_canonical_hook only for software modes Andrey Konovalov
2020-09-15 21:15 ` [PATCH v2 17/37] kasan: rename SHADOW layout macros to META Andrey Konovalov
2020-09-15 21:16 ` [PATCH v2 18/37] kasan: separate metadata_fetch_row for each mode Andrey Konovalov
2020-09-15 21:16 ` [PATCH v2 19/37] kasan: don't allow SW_TAGS with ARM64_MTE Andrey Konovalov
2020-09-17 17:05 ` Catalin Marinas
2020-09-15 21:16 ` [PATCH v2 20/37] kasan: rename tags.c to tags_sw.c Andrey Konovalov
2020-09-18 9:41 ` Alexander Potapenko
2020-09-18 9:44 ` Alexander Potapenko
2020-09-18 9:46 ` Alexander Potapenko
2020-09-18 10:42 ` Andrey Konovalov
2020-09-15 21:16 ` [PATCH v2 21/37] kasan: introduce CONFIG_KASAN_HW_TAGS Andrey Konovalov
2020-09-18 12:32 ` Marco Elver
2020-09-18 15:06 ` Andrey Konovalov
2020-09-18 15:36 ` Marco Elver
2020-09-18 15:45 ` Andrey Konovalov
2020-09-15 21:16 ` [PATCH v2 22/37] arm64: mte: Add in-kernel MTE helpers Andrey Konovalov
2020-09-17 13:46 ` Catalin Marinas
2020-09-17 14:21 ` Vincenzo Frascino
2020-09-18 9:36 ` Catalin Marinas
2020-09-22 10:16 ` Vincenzo Frascino
2020-09-17 16:17 ` Vincenzo Frascino
2020-09-17 17:07 ` Catalin Marinas
2020-09-15 21:16 ` [PATCH v2 23/37] arm64: kasan: Add arch layer for memory tagging helpers Andrey Konovalov
2020-09-17 17:05 ` Catalin Marinas
2020-09-18 13:00 ` Marco Elver
2020-09-18 14:56 ` Andrey Konovalov
2020-09-15 21:16 ` [PATCH v2 24/37] arm64: mte: Add in-kernel tag fault handler Andrey Konovalov
2020-09-17 14:03 ` Catalin Marinas
2020-09-17 14:24 ` Vincenzo Frascino
2020-09-17 14:59 ` Catalin Marinas
2020-09-15 21:16 ` [PATCH v2 25/37] arm64: kasan: Enable in-kernel MTE Andrey Konovalov
2020-09-17 16:35 ` Catalin Marinas
2020-09-15 21:16 ` [PATCH v2 26/37] arm64: mte: Convert gcr_user into an exclude mask Andrey Konovalov
2020-09-17 17:06 ` Catalin Marinas
2020-09-15 21:16 ` Andrey Konovalov [this message]
2020-09-17 16:52 ` [PATCH v2 27/37] arm64: mte: Switch GCR_EL1 in kernel entry and exit Catalin Marinas
2020-09-17 16:58 ` Catalin Marinas
2020-09-17 18:47 ` Vincenzo Frascino
2020-09-18 9:39 ` Catalin Marinas
2020-09-15 21:16 ` [PATCH v2 28/37] arm64: kasan: Enable TBI EL1 Andrey Konovalov
2020-09-17 16:54 ` Catalin Marinas
2020-09-15 21:16 ` [PATCH v2 29/37] arm64: kasan: Align allocations for HW_TAGS Andrey Konovalov
2020-09-17 17:06 ` Catalin Marinas
2020-09-15 21:16 ` [PATCH v2 30/37] kasan: define KASAN_GRANULE_SIZE " Andrey Konovalov
2020-09-15 21:16 ` [PATCH v2 31/37] kasan, x86, s390: update undef CONFIG_KASAN Andrey Konovalov
2020-09-18 10:52 ` Marco Elver
2020-09-18 15:07 ` Andrey Konovalov
2020-09-24 21:35 ` Andrey Konovalov
2020-09-15 21:16 ` [PATCH v2 32/37] kasan, arm64: expand CONFIG_KASAN checks Andrey Konovalov
2020-09-17 17:06 ` Catalin Marinas
2020-09-15 21:16 ` [PATCH v2 33/37] kasan, arm64: implement HW_TAGS runtime Andrey Konovalov
2020-09-17 17:06 ` Catalin Marinas
2020-09-18 10:46 ` Marco Elver
2020-09-18 12:28 ` Andrey Konovalov
2020-09-18 12:52 ` Marco Elver
2020-09-18 15:00 ` Andrey Konovalov
2020-09-18 15:19 ` Marco Elver
2020-09-18 15:52 ` Andrey Konovalov
2020-09-15 21:16 ` [PATCH v2 34/37] kasan, arm64: print report from tag fault handler Andrey Konovalov
2020-09-17 17:04 ` Catalin Marinas
2020-09-18 12:26 ` Andrey Konovalov
2020-09-15 21:16 ` [PATCH v2 35/37] kasan, slub: reset tags when accessing metadata Andrey Konovalov
2020-09-18 14:44 ` Marco Elver
2020-09-18 14:55 ` Andrey Konovalov
2020-09-18 15:29 ` Catalin Marinas
2020-09-15 21:16 ` [PATCH v2 36/37] kasan, arm64: enable CONFIG_KASAN_HW_TAGS Andrey Konovalov
2020-09-17 17:04 ` Catalin Marinas
2020-09-15 21:16 ` [PATCH v2 37/37] kasan: add documentation for hardware tag-based mode Andrey Konovalov
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