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authorAndrey Konovalov2021-02-25 17:20:31 -0800
committerLinus Torvalds2021-02-26 09:41:03 -0800
commit2cb34276427a093e2d7cc6ea63ac447bad1ff4c1 (patch)
tree0c3fb40586ab34827c06710f8c3ec769fcbb01a5
parentcde8a7eb778c7c71f70d636aa0bb1ec081b9167c (diff)
arm64: kasan: simplify and inline MTE functions
This change provides a simpler implementation of mte_get_mem_tag(), mte_get_random_tag(), and mte_set_mem_tag_range(). Simplifications include removing system_supports_mte() checks as these functions are onlye called from KASAN runtime that had already checked system_supports_mte(). Besides that, size and address alignment checks are removed from mte_set_mem_tag_range(), as KASAN now does those. This change also moves these functions into the asm/mte-kasan.h header and implements mte_set_mem_tag_range() via inline assembly to avoid unnecessary functions calls. [vincenzo.frascino@arm.com: fix warning in mte_get_random_tag()] Link: https://lkml.kernel.org/r/20210211152208.23811-1-vincenzo.frascino@arm.com Link: https://lkml.kernel.org/r/a26121b294fdf76e369cb7a74351d1c03a908930.1612546384.git.andreyknvl@google.com Co-developed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Catalin Marinas <catalin.marinas@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: Peter Collingbourne <pcc@google.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/arm64/include/asm/cache.h1
-rw-r--r--arch/arm64/include/asm/kasan.h1
-rw-r--r--arch/arm64/include/asm/mte-def.h2
-rw-r--r--arch/arm64/include/asm/mte-kasan.h65
-rw-r--r--arch/arm64/include/asm/mte.h2
-rw-r--r--arch/arm64/kernel/mte.c46
-rw-r--r--arch/arm64/lib/mte.S16
7 files changed, 60 insertions, 73 deletions
diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h
index 77cbbe3625f2..a074459f8f2f 100644
--- a/arch/arm64/include/asm/cache.h
+++ b/arch/arm64/include/asm/cache.h
@@ -6,7 +6,6 @@
#define __ASM_CACHE_H
#include <asm/cputype.h>
-#include <asm/mte-kasan.h>
#define CTR_L1IP_SHIFT 14
#define CTR_L1IP_MASK 3
diff --git a/arch/arm64/include/asm/kasan.h b/arch/arm64/include/asm/kasan.h
index 0aaf9044cd6a..12d5f47f7dbe 100644
--- a/arch/arm64/include/asm/kasan.h
+++ b/arch/arm64/include/asm/kasan.h
@@ -6,6 +6,7 @@
#include <linux/linkage.h>
#include <asm/memory.h>
+#include <asm/mte-kasan.h>
#include <asm/pgtable-types.h>
#define arch_kasan_set_tag(addr, tag) __tag_set(addr, tag)
diff --git a/arch/arm64/include/asm/mte-def.h b/arch/arm64/include/asm/mte-def.h
index 2d73a1612f09..cf241b0f0a42 100644
--- a/arch/arm64/include/asm/mte-def.h
+++ b/arch/arm64/include/asm/mte-def.h
@@ -11,4 +11,6 @@
#define MTE_TAG_SIZE 4
#define MTE_TAG_MASK GENMASK((MTE_TAG_SHIFT + (MTE_TAG_SIZE - 1)), MTE_TAG_SHIFT)
+#define __MTE_PREAMBLE ARM64_ASM_PREAMBLE ".arch_extension memtag\n"
+
#endif /* __ASM_MTE_DEF_H */
diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h
index 3748d5bb88c0..7ab500e2ad17 100644
--- a/arch/arm64/include/asm/mte-kasan.h
+++ b/arch/arm64/include/asm/mte-kasan.h
@@ -11,11 +11,14 @@
#include <linux/types.h>
+#ifdef CONFIG_ARM64_MTE
+
/*
- * The functions below are meant to be used only for the
- * KASAN_HW_TAGS interface defined in asm/memory.h.
+ * These functions are meant to be only used from KASAN runtime through
+ * the arch_*() interface defined in asm/memory.h.
+ * These functions don't include system_supports_mte() checks,
+ * as KASAN only calls them when MTE is supported and enabled.
*/
-#ifdef CONFIG_ARM64_MTE
static inline u8 mte_get_ptr_tag(void *ptr)
{
@@ -25,9 +28,54 @@ static inline u8 mte_get_ptr_tag(void *ptr)
return tag;
}
-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);
+/* Get allocation tag for the address. */
+static inline u8 mte_get_mem_tag(void *addr)
+{
+ asm(__MTE_PREAMBLE "ldg %0, [%0]"
+ : "+r" (addr));
+
+ return mte_get_ptr_tag(addr);
+}
+
+/* Generate a random tag. */
+static inline u8 mte_get_random_tag(void)
+{
+ void *addr;
+
+ asm(__MTE_PREAMBLE "irg %0, %0"
+ : "=r" (addr));
+
+ return mte_get_ptr_tag(addr);
+}
+
+/*
+ * Assign allocation tags for a region of memory based on the pointer tag.
+ * Note: The address must be non-NULL and MTE_GRANULE_SIZE aligned and
+ * size must be non-zero and MTE_GRANULE_SIZE aligned.
+ */
+static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
+{
+ u64 curr, end;
+
+ if (!size)
+ return;
+
+ curr = (u64)__tag_set(addr, tag);
+ end = curr + size;
+
+ do {
+ /*
+ * 'asm volatile' is required to prevent the compiler to move
+ * the statement outside of the loop.
+ */
+ asm volatile(__MTE_PREAMBLE "stg %0, [%0]"
+ :
+ : "r" (curr)
+ : "memory");
+
+ curr += MTE_GRANULE_SIZE;
+ } while (curr != end);
+}
void mte_enable_kernel(void);
void mte_init_tags(u64 max_tag);
@@ -46,13 +94,14 @@ static inline u8 mte_get_mem_tag(void *addr)
{
return 0xFF;
}
+
static inline u8 mte_get_random_tag(void)
{
return 0xFF;
}
-static inline void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
+
+static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
{
- return addr;
}
static inline void mte_enable_kernel(void)
diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index d02aff9f493d..9b557a457f24 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -8,8 +8,6 @@
#include <asm/compiler.h>
#include <asm/mte-def.h>
-#define __MTE_PREAMBLE ARM64_ASM_PREAMBLE ".arch_extension memtag\n"
-
#ifndef __ASSEMBLY__
#include <linux/bitfield.h>
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index 2cfc850809ce..b3c70a612c7a 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -19,7 +19,6 @@
#include <asm/barrier.h>
#include <asm/cpufeature.h>
#include <asm/mte.h>
-#include <asm/mte-kasan.h>
#include <asm/ptrace.h>
#include <asm/sysreg.h>
@@ -88,51 +87,6 @@ int memcmp_pages(struct page *page1, struct page *page2)
return ret;
}
-u8 mte_get_mem_tag(void *addr)
-{
- if (!system_supports_mte())
- return 0xFF;
-
- asm(__MTE_PREAMBLE "ldg %0, [%0]"
- : "+r" (addr));
-
- return mte_get_ptr_tag(addr);
-}
-
-u8 mte_get_random_tag(void)
-{
- void *addr;
-
- if (!system_supports_mte())
- return 0xFF;
-
- asm(__MTE_PREAMBLE "irg %0, %0"
- : "+r" (addr));
-
- return mte_get_ptr_tag(addr);
-}
-
-void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
-{
- void *ptr = addr;
-
- if ((!system_supports_mte()) || (size == 0))
- return addr;
-
- /* Make sure that size is MTE granule aligned. */
- WARN_ON(size & (MTE_GRANULE_SIZE - 1));
-
- /* Make sure that the address is MTE granule aligned. */
- WARN_ON((u64)addr & (MTE_GRANULE_SIZE - 1));
-
- tag = 0xF0 | tag;
- ptr = (void *)__tag_set(ptr, tag);
-
- mte_assign_mem_tag_range(ptr, size);
-
- return ptr;
-}
-
void mte_init_tags(u64 max_tag)
{
static bool gcr_kernel_excl_initialized;
diff --git a/arch/arm64/lib/mte.S b/arch/arm64/lib/mte.S
index 9e1a12e10053..351537c12f36 100644
--- a/arch/arm64/lib/mte.S
+++ b/arch/arm64/lib/mte.S
@@ -149,19 +149,3 @@ SYM_FUNC_START(mte_restore_page_tags)
ret
SYM_FUNC_END(mte_restore_page_tags)
-
-/*
- * Assign allocation tags for a region of memory based on the pointer tag
- * x0 - source pointer
- * x1 - size
- *
- * Note: The address must be non-NULL and MTE_GRANULE_SIZE aligned and
- * size must be non-zero and MTE_GRANULE_SIZE aligned.
- */
-SYM_FUNC_START(mte_assign_mem_tag_range)
-1: stg x0, [x0]
- add x0, x0, #MTE_GRANULE_SIZE
- subs x1, x1, #MTE_GRANULE_SIZE
- b.gt 1b
- ret
-SYM_FUNC_END(mte_assign_mem_tag_range)