+
+#define untagged_addr_remote(mm, addr) ({ \
+ unsigned long __addr = (__force unsigned long)(addr); \
+ mmap_assert_locked(mm); \
+ (__force __typeof__(addr))__untagged_addr_remote(mm, __addr); \
+})
+
+#define access_ok(addr, size) likely(__access_ok(untagged_addr(addr), size))
+#else
+#define untagged_addr(addr) (addr)
+#endif
+
/*
* User space memory access functions
*/
@@ -130,7 +178,7 @@ do { \
*/
#define __get_user(x, ptr) \
({ \
- const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \
+ const __typeof__(*(ptr)) __user *__gu_ptr = untagged_addr(ptr); \
long __gu_err = 0; \
\
__chk_user_ptr(__gu_ptr); \
@@ -246,7 +294,7 @@ do { \
*/
#define __put_user(x, ptr) \
({ \
- __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \
+ __typeof__(*(ptr)) __user *__gu_ptr = untagged_addr(ptr); \
__typeof__(*__gu_ptr) __val = (x); \
long __pu_err = 0; \
\
@@ -293,13 +341,13 @@ unsigned long __must_check __asm_copy_from_user(void *to,
static inline unsigned long
raw_copy_from_user(void *to, const void __user *from, unsigned long n)
{
- return __asm_copy_from_user(to, from, n);
+ return __asm_copy_from_user(to, untagged_addr(from), n);
}
static inline unsigned long
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
- return __asm_copy_to_user(to, from, n);
+ return __asm_copy_to_user(untagged_addr(to), from, n);
}
extern long strncpy_from_user(char *dest, const char __user *src, long
count);
@@ -314,7 +362,7 @@ unsigned long __must_check clear_user(void __user *to,
unsigned long n)
{
might_fault();
return access_ok(to, n) ?
- __clear_user(to, n) : n;
+ __clear_user(untagged_addr(to), n) : n;
}
#define __get_kernel_nofault(dst, src, type, err_label) \
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 1280a7c4a412..f4d8e5c3bb84 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -203,6 +203,10 @@ int copy_thread(struct task_struct *p, const struct
kernel_clone_args *args)
unsigned long tls = args->tls;
struct pt_regs *childregs = task_pt_regs(p);
+ /* Ensure all threads in this mm have the same pointer masking mode. */
+ if (IS_ENABLED(CONFIG_RISCV_ISA_SUPM) && p->mm && (clone_flags & CLONE_VM))
+ set_bit(MM_CONTEXT_LOCK_PMLEN, &p->mm->context.flags);
+
memset(&p->thread.s, 0, sizeof(p->thread.s));
/* p->thread holds context to be restored by __switch_to() */
@@ -248,10 +252,16 @@ enum {
static bool have_user_pmlen_7;
static bool have_user_pmlen_16;
+/*
+ * Control the relaxed ABI allowing tagged user addresses into the kernel.
+ */
+static unsigned int tagged_addr_disabled;
+
long set_tagged_addr_ctrl(struct task_struct *task, unsigned long arg)
{
- unsigned long valid_mask = PR_PMLEN_MASK;
+ unsigned long valid_mask = PR_PMLEN_MASK | PR_TAGGED_ADDR_ENABLE;
struct thread_info *ti = task_thread_info(task);
+ struct mm_struct *mm = task->mm;
unsigned long pmm;
u8 pmlen;
@@ -266,16 +276,41 @@ long set_tagged_addr_ctrl(struct task_struct *task,
unsigned long arg)
* in case choosing a larger PMLEN has a performance impact.
*/
pmlen = FIELD_GET(PR_PMLEN_MASK, arg);
- if (pmlen == PMLEN_0)
+ if (pmlen == PMLEN_0) {
pmm = ENVCFG_PMM_PMLEN_0;
- else if (pmlen <= PMLEN_7 && have_user_pmlen_7)
+ } else if (pmlen <= PMLEN_7 && have_user_pmlen_7) {
+ pmlen = PMLEN_7;
pmm = ENVCFG_PMM_PMLEN_7;
- else if (pmlen <= PMLEN_16 && have_user_pmlen_16)
+ } else if (pmlen <= PMLEN_16 && have_user_pmlen_16) {
+ pmlen = PMLEN_16;
pmm = ENVCFG_PMM_PMLEN_16;
- else
+ } else {
return -EINVAL;
+ }
+
+ /*
+ * Do not allow the enabling of the tagged address ABI if globally
+ * disabled via sysctl abi.tagged_addr_disabled, if pointer masking
+ * is disabled for userspace.
+ */
+ if (arg & PR_TAGGED_ADDR_ENABLE && (tagged_addr_disabled || !pmlen))
+ return -EINVAL;
+
+ if (!(arg & PR_TAGGED_ADDR_ENABLE))
+ pmlen = PMLEN_0;
+
+ if (mmap_write_lock_killable(mm))
+ return -EINTR;
+
+ if (test_bit(MM_CONTEXT_LOCK_PMLEN, &mm->context.flags) &&
mm->context.pmlen != pmlen) {
+ mmap_write_unlock(mm);
+ return -EBUSY;
+ }
envcfg_update_bits(task, ENVCFG_PMM, pmm);
+ mm->context.pmlen = pmlen;
+
+ mmap_write_unlock(mm);
return 0;
}
@@ -288,6 +323,10 @@ long get_tagged_addr_ctrl(struct task_struct *task)
if (is_compat_thread(ti))
return -EINVAL;
+ /*
+ * The mm context's pmlen is set only when the tagged address ABI is
+ * enabled, so the effective PMLEN must be extracted from envcfg.PMM.
+ */
switch (task->thread.envcfg & ENVCFG_PMM) {
case ENVCFG_PMM_PMLEN_7:
ret = FIELD_PREP(PR_PMLEN_MASK, PMLEN_7);
@@ -297,6 +336,9 @@ long get_tagged_addr_ctrl(struct task_struct *task)
break;
}
+ if (task->mm->context.pmlen)
+ ret |= PR_TAGGED_ADDR_ENABLE;
+
return ret;
}
@@ -306,6 +348,24 @@ static bool try_to_set_pmm(unsigned long value)
return (csr_read_clear(CSR_ENVCFG, ENVCFG_PMM) & ENVCFG_PMM) == value;
}
+/*
+ * Global sysctl to disable the tagged user addresses support. This control
+ * only prevents the tagged address ABI enabling via prctl() and does not
+ * disable it for tasks that already opted in to the relaxed ABI.
+ */
+
+static struct ctl_table tagged_addr_sysctl_table[] = {
+ {
+ .procname = "tagged_addr_disabled",
+ .mode = 0644,
+ .data = &tagged_addr_disabled,
+ .maxlen = sizeof(int),
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
+ },
+};
+
static int __init tagged_addr_init(void)
{
if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM))
@@ -319,6 +379,9 @@ static int __init tagged_addr_init(void)
have_user_pmlen_7 = try_to_set_pmm(ENVCFG_PMM_PMLEN_7);
have_user_pmlen_16 = try_to_set_pmm(ENVCFG_PMM_PMLEN_16);
+ if (!register_sysctl("abi", tagged_addr_sysctl_table))
+ return -EINVAL;
+
return 0;
}
core_initcall(tagged_addr_init);
