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: Andrey Ryabinin <aryabinin@virtuozzo.com>,
Alexander Potapenko <glider@google.com>,
Marco Elver <elver@google.com>,
Evgenii Stepanov <eugenis@google.com>,
Elena Petrova <lenaptr@google.com>,
Branislav Rankov <Branislav.Rankov@arm.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Will Deacon <will.deacon@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 24/35] arm64: mte: Switch GCR_EL1 in kernel entry and exit
Date: Fri, 14 Aug 2020 19:27:06 +0200 [thread overview]
Message-ID: <ec314a9589ef8db18494d533b6eaf1fd678dc010.1597425745.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1597425745.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>
---
arch/arm64/include/asm/mte.h | 8 ++++++++
arch/arm64/kernel/asm-offsets.c | 3 +++
arch/arm64/kernel/cpufeature.c | 5 +++--
arch/arm64/kernel/entry.S | 28 ++++++++++++++++++++++++++++
arch/arm64/kernel/mte.c | 19 +++++++++++++++++--
5 files changed, 59 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index 733be1cb5c95..4929f744d103 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -21,6 +21,8 @@
#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);
@@ -59,6 +61,8 @@ 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 */
/* unused if !CONFIG_ARM64_MTE, silence the compiler */
@@ -120,6 +124,10 @@ 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/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 0577e2142284..a1ef256cad4f 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 4d94af19d8f6..54bc3b315063 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1665,14 +1665,15 @@ static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap)
{
u64 mair;
- /* all non-zero tags excluded by default */
- write_sysreg_s(SYS_GCR_EL1_RRND | SYS_GCR_EL1_EXCL_MASK, SYS_GCR_EL1);
write_sysreg_s(0, SYS_TFSR_EL1);
write_sysreg_s(0, SYS_TFSRE0_EL1);
/* Enable Match-All at EL1 */
sysreg_clear_set(tcr_el1, 0, SYS_TCR_EL1_TCMA1);
+ /* Enable the kernel exclude mask for random tags generation */
+ write_sysreg_s((SYS_GCR_EL1_RRND | gcr_kernel_excl), SYS_GCR_EL1);
+
/*
* CnP must be enabled only after the MAIR_EL1 register has been set
* up. Inconsistent MAIR_EL1 between CPUs sharing the same TLB may
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index cde127508e38..a17fefb0571b 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -172,6 +172,29 @@ alternative_else_nop_endif
#endif
.endm
+ /* Note: tmp should always be a callee-saved register */
+ .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
@@ -209,6 +232,8 @@ 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
@@ -386,6 +411,8 @@ 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
@@ -957,6 +984,7 @@ SYM_FUNC_START(cpu_switch_to)
mov sp, x9
msr sp_el0, x1
ptrauth_keys_install_kernel x1, x8, x9, x10
+ mte_restore_gcr 1, x1, x8, x9
scs_save x0, x8
scs_load x1, x8
ret
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index 7717ea9bc2a7..cfac7d02f032 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -18,10 +18,14 @@
#include <asm/barrier.h>
#include <asm/cpufeature.h>
+#include <asm/kasan.h>
+#include <asm/kprobes.h>
#include <asm/mte.h>
#include <asm/ptrace.h>
#include <asm/sysreg.h>
+u64 gcr_kernel_excl __read_mostly;
+
static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap)
{
pte_t old_pte = READ_ONCE(*ptep);
@@ -115,6 +119,13 @@ void * __must_check mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
return ptr;
}
+void mte_init_tags(u64 max_tag)
+{
+ u64 incl = ((1ULL << ((max_tag & MTE_TAG_MAX) + 1)) - 1);
+
+ gcr_kernel_excl = ~incl & SYS_GCR_EL1_EXCL_MASK;
+}
+
static void update_sctlr_el1_tcf0(u64 tcf0)
{
/* ISB required for the kernel uaccess routines */
@@ -150,7 +161,11 @@ 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)
@@ -184,7 +199,7 @@ 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)
--
2.28.0.220.ged08abb693-goog
next prev parent reply other threads:[~2020-08-14 17:29 UTC|newest]
Thread overview: 94+ 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
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 ` Andrey Konovalov [this message]
2020-08-27 10:38 ` [PATCH 24/35] arm64: mte: Switch GCR_EL1 in kernel entry and exit 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
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