@@ -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 */
@@ -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__ */
@@ -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);
@@ -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]));
@@ -1707,6 +1707,9 @@ 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();
@@ -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
@@ -330,6 +369,8 @@ 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
@@ -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);
@@ -121,6 +123,17 @@ void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
return ptr;
}
+void mte_init_tags(u64 max_tag)
+{
+ /*
+ * The format of the tags in KASAN is 0xFF and in MTE is 0xF.
+ * This conversion is required to extract the MTE tag from a KASAN one.
+ */
+ u64 incl = GENMASK(FIELD_GET(MTE_TAG_MASK >> MTE_TAG_SHIFT, max_tag), 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 */
@@ -156,7 +169,11 @@ 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)
@@ -182,7 +199,6 @@ 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)
@@ -190,7 +206,7 @@ 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)