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,
Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH v4 29/39] arm64: mte: Switch GCR_EL1 in kernel entry and exit
Date: Fri, 2 Oct 2020 01:10:30 +0200 [thread overview]
Message-ID: <1f2681fdff1aa1096df949cb8634a9be6bf4acc4.1601593784.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1601593784.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-kasan.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 | 41 ++++++++++++++++++++++++++++++
arch/arm64/kernel/mte.c | 18 ++++++++++---
6 files changed, 70 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h
index 3a70fb1807fd..a4c61b926d4a 100644
--- a/arch/arm64/include/asm/mte-kasan.h
+++ b/arch/arm64/include/asm/mte-kasan.h
@@ -29,6 +29,8 @@ 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 */
static inline u8 mte_get_ptr_tag(void *ptr)
@@ -49,6 +51,10 @@ 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 cf1cd181dcb2..d02aff9f493d 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -18,6 +18,8 @@
#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..e76634ad5bc7 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..eeaac91021bf 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -175,6 +175,43 @@ alternative_else_nop_endif
#endif
.endm
+ .macro mte_set_gcr, tmp, tmp2
+#ifdef CONFIG_ARM64_MTE
+ /*
+ * 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
+#endif
+ .endm
+
+ .macro mte_set_kernel_gcr, tmp, tmp2
+#ifdef CONFIG_KASAN_HW_TAGS
+alternative_if_not ARM64_MTE
+ b 1f
+alternative_else_nop_endif
+ ldr_l \tmp, gcr_kernel_excl
+
+ mte_set_gcr \tmp, \tmp2
+1:
+#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 +251,8 @@ alternative_else_nop_endif
ptrauth_keys_install_kernel tsk, x20, x22, x23
+ mte_set_kernel_gcr x22, x23
+
scs_load tsk, x20
.else
add x21, sp, #S_FRAME_SIZE
@@ -332,6 +371,8 @@ 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 7c67ac6f08df..d1847f29f59b 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -23,6 +23,8 @@
#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);
@@ -120,6 +122,13 @@ 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 +164,11 @@ 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_excl value
+ * by mte_set_user_gcr() in kernel_exit,
+ */
}
void flush_mte_state(void)
@@ -181,7 +194,6 @@ 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 +201,7 @@ 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)
--
2.28.0.709.gb0816b6eb0-goog
next prev parent reply other threads:[~2020-10-01 23:11 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 23:10 [PATCH v4 00/39] kasan: add hardware tag-based mode for arm64 Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 01/39] kasan: drop unnecessary GPL text from comment headers Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 02/39] kasan: KASAN_VMALLOC depends on KASAN_GENERIC Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 03/39] kasan: group vmalloc code Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 04/39] kasan: shadow declarations only for software modes Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 05/39] kasan: rename (un)poison_shadow to (un)poison_memory Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 06/39] kasan: rename KASAN_SHADOW_* to KASAN_GRANULE_* Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 07/39] kasan: only build init.c for software modes Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 08/39] kasan: split out shadow.c from common.c Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 09/39] kasan: define KASAN_GRANULE_PAGE Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 10/39] kasan: rename report and tags files Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 11/39] kasan: don't duplicate config dependencies Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 12/39] kasan: hide invalid free check implementation Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 13/39] kasan: decode stack frame only with KASAN_STACK_ENABLE Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 14/39] kasan, arm64: only init shadow for software modes Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 15/39] kasan, arm64: only use kasan_depth " Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 16/39] kasan: rename addr_has_shadow to addr_has_metadata Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 17/39] kasan: rename print_shadow_for_address to print_memory_metadata Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 18/39] kasan: kasan_non_canonical_hook only for software modes Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 19/39] kasan: rename SHADOW layout macros to META Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 20/39] kasan: separate metadata_fetch_row for each mode Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 21/39] kasan, arm64: don't allow SW_TAGS with ARM64_MTE Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 22/39] kasan: introduce CONFIG_KASAN_HW_TAGS Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 23/39] arm64: Enable armv8.5-a asm-arch option Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 24/39] arm64: mte: Add in-kernel MTE helpers Andrey Konovalov
2020-10-02 13:51 ` Catalin Marinas
2020-10-01 23:10 ` [PATCH v4 25/39] arm64: kasan: Add arch layer for memory tagging helpers Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 26/39] arm64: mte: Add in-kernel tag fault handler Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 27/39] arm64: kasan: Enable in-kernel MTE Andrey Konovalov
2020-10-02 14:00 ` Catalin Marinas
2020-10-01 23:10 ` [PATCH v4 28/39] arm64: mte: Convert gcr_user into an exclude mask Andrey Konovalov
2020-10-01 23:10 ` Andrey Konovalov [this message]
2020-10-02 14:06 ` [PATCH v4 29/39] arm64: mte: Switch GCR_EL1 in kernel entry and exit Catalin Marinas
2020-10-08 18:24 ` Vincenzo Frascino
2020-10-09 8:11 ` Catalin Marinas
2020-10-09 9:56 ` Vincenzo Frascino
2020-10-09 10:16 ` Catalin Marinas
2020-10-09 10:21 ` Vincenzo Frascino
2020-10-01 23:10 ` [PATCH v4 30/39] arm64: kasan: Enable TBI EL1 Andrey Konovalov
2020-10-02 14:10 ` Catalin Marinas
2020-10-01 23:10 ` [PATCH v4 31/39] arm64: kasan: Align allocations for HW_TAGS Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 32/39] kasan: define KASAN_GRANULE_SIZE " Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 33/39] kasan, x86, s390: update undef CONFIG_KASAN Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 34/39] kasan, arm64: expand CONFIG_KASAN checks Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 35/39] kasan, arm64: implement HW_TAGS runtime Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 36/39] kasan, arm64: print report from tag fault handler Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 37/39] kasan, mm: reset tags when accessing metadata Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 38/39] kasan, arm64: enable CONFIG_KASAN_HW_TAGS Andrey Konovalov
2020-10-01 23:10 ` [PATCH v4 39/39] kasan: add documentation for hardware tag-based mode Andrey Konovalov
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