From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, andreyknvl@google.com,
aryabinin@virtuozzo.com, Branislav.Rankov@arm.com,
catalin.marinas@arm.com, dvyukov@google.com, elver@google.com,
eugenis@google.com, glider@google.com, gor@linux.ibm.com,
kevin.brodsky@arm.com, linux-mm@kvack.org,
mm-commits@vger.kernel.org, torvalds@linux-foundation.org,
vincenzo.frascino@arm.com, will.deacon@arm.com
Subject: [patch 29/60] arm64: mte: switch GCR_EL1 in kernel entry and exit
Date: Tue, 22 Dec 2020 12:01:45 -0800 [thread overview]
Message-ID: <20201222200145.zvzM87pBj%akpm@linux-foundation.org> (raw)
In-Reply-To: <20201222115844.d30aaef7df6f5b120d3e0c3d@linux-foundation.org>
From: Vincenzo Frascino <vincenzo.frascino@arm.com>
Subject: arm64: mte: switch GCR_EL1 in kernel entry and exit
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.
Link: https://lkml.kernel.org/r/578b03294708cc7258fad0dc9c2a2e809e5a8214.1606161801.git.andreyknvl@google.com
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Co-developed-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
arch/arm64/include/asm/mte-def.h | 1
arch/arm64/include/asm/mte-kasan.h | 5 +++
arch/arm64/include/asm/mte.h | 2 +
arch/arm64/kernel/asm-offsets.c | 3 +
arch/arm64/kernel/entry.S | 41 +++++++++++++++++++++++++++
arch/arm64/kernel/mte.c | 31 ++++++++++++++++++--
6 files changed, 79 insertions(+), 4 deletions(-)
--- a/arch/arm64/include/asm/mte-def.h~arm64-mte-switch-gcr_el1-in-kernel-entry-and-exit
+++ a/arch/arm64/include/asm/mte-def.h
@@ -10,6 +10,5 @@
#define MTE_TAG_SHIFT 56
#define MTE_TAG_SIZE 4
#define MTE_TAG_MASK GENMASK((MTE_TAG_SHIFT + (MTE_TAG_SIZE - 1)), MTE_TAG_SHIFT)
-#define MTE_TAG_MAX (MTE_TAG_MASK >> MTE_TAG_SHIFT)
#endif /* __ASM_MTE_DEF_H */
--- a/arch/arm64/include/asm/mte.h~arm64-mte-switch-gcr_el1-in-kernel-entry-and-exit
+++ a/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);
--- a/arch/arm64/include/asm/mte-kasan.h~arm64-mte-switch-gcr_el1-in-kernel-entry-and-exit
+++ a/arch/arm64/include/asm/mte-kasan.h
@@ -30,6 +30,7 @@ u8 mte_get_random_tag(void);
void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag);
void mte_enable_kernel(void);
+void mte_init_tags(u64 max_tag);
#else /* CONFIG_ARM64_MTE */
@@ -55,6 +56,10 @@ static inline void mte_enable_kernel(voi
{
}
+static inline void mte_init_tags(u64 max_tag)
+{
+}
+
#endif /* CONFIG_ARM64_MTE */
#endif /* __ASSEMBLY__ */
--- a/arch/arm64/kernel/asm-offsets.c~arm64-mte-switch-gcr_el1-in-kernel-entry-and-exit
+++ a/arch/arm64/kernel/asm-offsets.c
@@ -47,6 +47,9 @@ int main(void)
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]));
DEFINE(S_X2, offsetof(struct pt_regs, regs[2]));
--- a/arch/arm64/kernel/entry.S~arm64-mte-switch-gcr_el1-in-kernel-entry-and-exit
+++ a/arch/arm64/kernel/entry.S
@@ -173,6 +173,43 @@ 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
@@ -212,6 +249,8 @@ 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
@@ -315,6 +354,8 @@ 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
--- a/arch/arm64/kernel/mte.c~arm64-mte-switch-gcr_el1-in-kernel-entry-and-exit
+++ a/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);
@@ -129,6 +131,26 @@ void *mte_set_mem_tag_range(void *addr,
return ptr;
}
+void mte_init_tags(u64 max_tag)
+{
+ static bool gcr_kernel_excl_initialized;
+
+ if (!gcr_kernel_excl_initialized) {
+ /*
+ * The format of the tags in KASAN is 0xFF and in MTE is 0xF.
+ * This conversion extracts an MTE tag from a KASAN tag.
+ */
+ u64 incl = GENMASK(FIELD_GET(MTE_TAG_MASK >> MTE_TAG_SHIFT,
+ max_tag), 0);
+
+ gcr_kernel_excl = ~incl & SYS_GCR_EL1_EXCL_MASK;
+ gcr_kernel_excl_initialized = true;
+ }
+
+ /* Enable the kernel exclude mask for random tags generation. */
+ write_sysreg_s(SYS_GCR_EL1_RRND | gcr_kernel_excl, SYS_GCR_EL1);
+}
+
void mte_enable_kernel(void)
{
/* Enable MTE Sync Mode for EL1. */
@@ -171,7 +193,11 @@ 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)
@@ -197,7 +223,6 @@ void mte_thread_switch(struct task_struc
/* 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)
@@ -205,7 +230,7 @@ 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)
_
next prev parent reply other threads:[~2020-12-22 20:02 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-22 19:58 incoming Andrew Morton
2020-12-22 20:00 ` [patch 01/60] kasan: drop unnecessary GPL text from comment headers Andrew Morton
2020-12-22 20:00 ` [patch 02/60] kasan: KASAN_VMALLOC depends on KASAN_GENERIC Andrew Morton
2020-12-22 20:00 ` [patch 03/60] kasan: group vmalloc code Andrew Morton
2020-12-22 20:00 ` [patch 04/60] kasan: shadow declarations only for software modes Andrew Morton
2020-12-22 20:00 ` [patch 05/60] kasan: rename (un)poison_shadow to (un)poison_range Andrew Morton
2020-12-22 20:00 ` [patch 06/60] kasan: rename KASAN_SHADOW_* to KASAN_GRANULE_* Andrew Morton
2020-12-22 20:00 ` [patch 07/60] kasan: only build init.c for software modes Andrew Morton
2020-12-22 20:00 ` [patch 08/60] kasan: split out shadow.c from common.c Andrew Morton
2020-12-22 20:00 ` [patch 09/60] kasan: define KASAN_MEMORY_PER_SHADOW_PAGE Andrew Morton
2020-12-22 20:00 ` [patch 10/60] kasan: rename report and tags files Andrew Morton
2020-12-22 20:00 ` [patch 11/60] kasan: don't duplicate config dependencies Andrew Morton
2020-12-22 20:00 ` [patch 12/60] kasan: hide invalid free check implementation Andrew Morton
2020-12-22 20:00 ` [patch 13/60] kasan: decode stack frame only with KASAN_STACK_ENABLE Andrew Morton
2020-12-22 20:00 ` [patch 14/60] kasan, arm64: only init shadow for software modes Andrew Morton
2020-12-22 20:00 ` [patch 15/60] kasan, arm64: only use kasan_depth " Andrew Morton
2020-12-22 20:01 ` [patch 16/60] kasan, arm64: move initialization message Andrew Morton
2020-12-22 20:01 ` [patch 17/60] kasan, arm64: rename kasan_init_tags and mark as __init Andrew Morton
2020-12-22 20:01 ` [patch 18/60] kasan: rename addr_has_shadow to addr_has_metadata Andrew Morton
2020-12-22 20:01 ` [patch 19/60] kasan: rename print_shadow_for_address to print_memory_metadata Andrew Morton
2020-12-22 20:01 ` [patch 20/60] kasan: rename SHADOW layout macros to META Andrew Morton
2020-12-22 20:01 ` [patch 21/60] kasan: separate metadata_fetch_row for each mode Andrew Morton
2020-12-22 20:01 ` [patch 22/60] kasan: introduce CONFIG_KASAN_HW_TAGS Andrew Morton
2020-12-22 20:01 ` [patch 23/60] arm64: enable armv8.5-a asm-arch option Andrew Morton
2020-12-22 20:01 ` [patch 24/60] arm64: mte: add in-kernel MTE helpers Andrew Morton
2020-12-22 20:01 ` [patch 25/60] arm64: mte: reset the page tag in page->flags Andrew Morton
2020-12-22 20:01 ` [patch 26/60] arm64: mte: add in-kernel tag fault handler Andrew Morton
2020-12-22 20:01 ` [patch 27/60] arm64: kasan: allow enabling in-kernel MTE Andrew Morton
2020-12-22 20:01 ` [patch 28/60] arm64: mte: convert gcr_user into an exclude mask Andrew Morton
2020-12-22 20:01 ` Andrew Morton [this message]
2020-12-22 20:01 ` [patch 30/60] kasan, mm: untag page address in free_reserved_area Andrew Morton
2020-12-22 20:01 ` [patch 31/60] arm64: kasan: align allocations for HW_TAGS Andrew Morton
2020-12-22 20:01 ` [patch 32/60] arm64: kasan: add arch layer for memory tagging helpers Andrew Morton
2020-12-22 20:01 ` [patch 33/60] kasan: define KASAN_GRANULE_SIZE for HW_TAGS Andrew Morton
2020-12-22 20:02 ` [patch 34/60] kasan, x86, s390: update undef CONFIG_KASAN Andrew Morton
2020-12-22 20:02 ` [patch 35/60] kasan, arm64: expand CONFIG_KASAN checks Andrew Morton
2020-12-22 20:02 ` [patch 36/60] kasan, arm64: implement HW_TAGS runtime Andrew Morton
2020-12-22 20:02 ` [patch 37/60] kasan, arm64: print report from tag fault handler Andrew Morton
2020-12-22 20:02 ` [patch 38/60] kasan, mm: reset tags when accessing metadata Andrew Morton
2020-12-22 20:02 ` [patch 39/60] kasan, arm64: enable CONFIG_KASAN_HW_TAGS Andrew Morton
2020-12-22 20:02 ` [patch 40/60] kasan: add documentation for hardware tag-based mode Andrew Morton
2020-12-22 20:02 ` [patch 41/60] kselftest/arm64: check GCR_EL1 after context switch Andrew Morton
2020-12-22 20:02 ` [patch 42/60] kasan: simplify quarantine_put call site Andrew Morton
2020-12-22 20:02 ` [patch 43/60] kasan: rename get_alloc/free_info Andrew Morton
2020-12-22 20:02 ` [patch 44/60] kasan: introduce set_alloc_info Andrew Morton
2020-12-22 20:02 ` [patch 45/60] kasan, arm64: unpoison stack only with CONFIG_KASAN_STACK Andrew Morton
2020-12-22 20:02 ` [patch 46/60] kasan: allow VMAP_STACK for HW_TAGS mode Andrew Morton
2020-12-22 20:02 ` [patch 47/60] kasan: remove __kasan_unpoison_stack Andrew Morton
2020-12-22 20:02 ` [patch 48/60] kasan: inline kasan_reset_tag for tag-based modes Andrew Morton
2020-12-22 20:02 ` [patch 49/60] kasan: inline random_tag for HW_TAGS Andrew Morton
2020-12-22 20:02 ` [patch 50/60] kasan: open-code kasan_unpoison_slab Andrew Morton
2020-12-22 20:03 ` [patch 51/60] kasan: inline (un)poison_range and check_invalid_free Andrew Morton
2020-12-22 20:03 ` [patch 52/60] kasan: add and integrate kasan boot parameters Andrew Morton
2020-12-22 20:03 ` [patch 53/60] kasan, mm: check kasan_enabled in annotations Andrew Morton
2020-12-22 20:03 ` [patch 54/60] kasan, mm: rename kasan_poison_kfree Andrew Morton
2020-12-22 20:03 ` [patch 55/60] kasan: don't round_up too much Andrew Morton
2020-12-22 20:03 ` [patch 56/60] kasan: simplify assign_tag and set_tag calls Andrew Morton
2020-12-22 20:03 ` [patch 57/60] kasan: clarify comment in __kasan_kfree_large Andrew Morton
2020-12-22 20:03 ` [patch 58/60] kasan: sanitize objects when metadata doesn't fit Andrew Morton
2020-12-22 20:03 ` [patch 59/60] kasan, mm: allow cache merging with no metadata Andrew Morton
2020-12-22 20:03 ` [patch 60/60] kasan: update documentation Andrew Morton
2020-12-22 21:43 ` incoming Linus Torvalds
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