diff mbox series

[v2] arm64: mte: Move MTE TCF0 check in entry-common

Message ID 20210409101902.2800-1-vincenzo.frascino@arm.com (mailing list archive)
State New, archived
Headers show
Series [v2] arm64: mte: Move MTE TCF0 check in entry-common | expand

Commit Message

Vincenzo Frascino April 9, 2021, 10:19 a.m. UTC 
The check_mte_async_tcf macro sets the TIF flag non-atomically. This can
race with another CPU doing a set_tsk_thread_flag() and all the other flags
can be lost in the process.

Move the tcf0 check to enter_from_user_mode() and clear tcf0 in
exit_to_user_mode() to address the problem.

Note: Moving the check in entry-common allows to use set_thread_flag()
which is safe.

Fixes: 637ec831ea4f ("arm64: mte: Handle synchronous and asynchronous tag check faults")
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: stable@vger.kernel.org
Reported-by: Will Deacon <will@kernel.org>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 arch/arm64/include/asm/mte.h     |  8 ++++++++
 arch/arm64/kernel/entry-common.c |  6 ++++++
 arch/arm64/kernel/entry.S        | 34 --------------------------------
 arch/arm64/kernel/mte.c          | 33 +++++++++++++++++++++++++++++--
 4 files changed, 45 insertions(+), 36 deletions(-)

Comments

kernel test robot April 9, 2021, 1:14 p.m. UTC | #1 
Hi Vincenzo,

I love your patch! Yet something to improve:

[auto build test ERROR on arm/for-next]
[also build test ERROR on soc/for-next kvmarm/next linus/master v5.12-rc6 next-20210408]
[cannot apply to arm64/for-next/core xlnx/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Vincenzo-Frascino/arm64-mte-Move-MTE-TCF0-check-in-entry-common/20210409-182215
base:   git://git.armlinux.org.uk/~rmk/linux-arm.git for-next
config: arm64-allnoconfig (attached as .config)
compiler: aarch64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/59174442d4b85039bfec7ede4825ff2b5c0b4331
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Vincenzo-Frascino/arm64-mte-Move-MTE-TCF0-check-in-entry-common/20210409-182215
        git checkout 59174442d4b85039bfec7ede4825ff2b5c0b4331
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All error/warnings (new ones prefixed by >>):

   In file included from arch/arm64/include/asm/pgtable.h:12,
                    from include/linux/pgtable.h:6,
                    from include/linux/mm.h:33,
                    from arch/arm64/kernel/asm-offsets.c:12:
>> arch/arm64/include/asm/mte.h:89:1: warning: ignoring attribute 'gnu_inline' because it conflicts with attribute 'noinline' [-Wattributes]
      89 | {
         | ^
   arch/arm64/include/asm/mte.h:34:14: note: previous declaration here
      34 | void noinstr check_mte_async_tcf0(void);
         |              ^~~~~~~~~~~~~~~~~~~~
>> arch/arm64/include/asm/mte.h:88:20: error: static declaration of 'check_mte_async_tcf0' follows non-static declaration
      88 | static inline void check_mte_async_tcf0(void)
         |                    ^~~~~~~~~~~~~~~~~~~~
   arch/arm64/include/asm/mte.h:34:14: note: previous declaration of 'check_mte_async_tcf0' was here
      34 | void noinstr check_mte_async_tcf0(void);
         |              ^~~~~~~~~~~~~~~~~~~~
   arch/arm64/include/asm/mte.h:92:1: warning: ignoring attribute 'gnu_inline' because it conflicts with attribute 'noinline' [-Wattributes]
      92 | {
         | ^
   arch/arm64/include/asm/mte.h:35:14: note: previous declaration here
      35 | void noinstr clear_mte_async_tcf0(void);
         |              ^~~~~~~~~~~~~~~~~~~~
>> arch/arm64/include/asm/mte.h:91:20: error: static declaration of 'clear_mte_async_tcf0' follows non-static declaration
      91 | static inline void clear_mte_async_tcf0(void)
         |                    ^~~~~~~~~~~~~~~~~~~~
   arch/arm64/include/asm/mte.h:35:14: note: previous declaration of 'clear_mte_async_tcf0' was here
      35 | void noinstr clear_mte_async_tcf0(void);
         |              ^~~~~~~~~~~~~~~~~~~~
--
   In file included from arch/arm64/include/asm/pgtable.h:12,
                    from include/linux/pgtable.h:6,
                    from include/linux/mm.h:33,
                    from arch/arm64/kernel/asm-offsets.c:12:
>> arch/arm64/include/asm/mte.h:89:1: warning: ignoring attribute 'gnu_inline' because it conflicts with attribute 'noinline' [-Wattributes]
      89 | {
         | ^
   arch/arm64/include/asm/mte.h:34:14: note: previous declaration here
      34 | void noinstr check_mte_async_tcf0(void);
         |              ^~~~~~~~~~~~~~~~~~~~
>> arch/arm64/include/asm/mte.h:88:20: error: static declaration of 'check_mte_async_tcf0' follows non-static declaration
      88 | static inline void check_mte_async_tcf0(void)
         |                    ^~~~~~~~~~~~~~~~~~~~
   arch/arm64/include/asm/mte.h:34:14: note: previous declaration of 'check_mte_async_tcf0' was here
      34 | void noinstr check_mte_async_tcf0(void);
         |              ^~~~~~~~~~~~~~~~~~~~
   arch/arm64/include/asm/mte.h:92:1: warning: ignoring attribute 'gnu_inline' because it conflicts with attribute 'noinline' [-Wattributes]
      92 | {
         | ^
   arch/arm64/include/asm/mte.h:35:14: note: previous declaration here
      35 | void noinstr clear_mte_async_tcf0(void);
         |              ^~~~~~~~~~~~~~~~~~~~
>> arch/arm64/include/asm/mte.h:91:20: error: static declaration of 'clear_mte_async_tcf0' follows non-static declaration
      91 | static inline void clear_mte_async_tcf0(void)
         |                    ^~~~~~~~~~~~~~~~~~~~
   arch/arm64/include/asm/mte.h:35:14: note: previous declaration of 'clear_mte_async_tcf0' was here
      35 | void noinstr clear_mte_async_tcf0(void);
         |              ^~~~~~~~~~~~~~~~~~~~
   make[2]: *** [scripts/Makefile.build:116: arch/arm64/kernel/asm-offsets.s] Error 1
   make[2]: Target '__build' not remade because of errors.
   make[1]: *** [Makefile:1233: prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:215: __sub-make] Error 2
   make: Target 'prepare' not remade because of errors.


vim +/check_mte_async_tcf0 +88 arch/arm64/include/asm/mte.h

    20	
    21	void mte_clear_page_tags(void *addr);
    22	unsigned long mte_copy_tags_from_user(void *to, const void __user *from,
    23					      unsigned long n);
    24	unsigned long mte_copy_tags_to_user(void __user *to, void *from,
    25					    unsigned long n);
    26	int mte_save_tags(struct page *page);
    27	void mte_save_page_tags(const void *page_addr, void *tag_storage);
    28	bool mte_restore_tags(swp_entry_t entry, struct page *page);
    29	void mte_restore_page_tags(void *page_addr, const void *tag_storage);
    30	void mte_invalidate_tags(int type, pgoff_t offset);
    31	void mte_invalidate_tags_area(int type);
    32	void *mte_allocate_tag_storage(void);
    33	void mte_free_tag_storage(char *storage);
  > 34	void noinstr check_mte_async_tcf0(void);
    35	void noinstr clear_mte_async_tcf0(void);
    36	
    37	#ifdef CONFIG_ARM64_MTE
    38	
    39	/* track which pages have valid allocation tags */
    40	#define PG_mte_tagged	PG_arch_2
    41	
    42	void mte_sync_tags(pte_t *ptep, pte_t pte);
    43	void mte_copy_page_tags(void *kto, const void *kfrom);
    44	void flush_mte_state(void);
    45	void mte_thread_switch(struct task_struct *next);
    46	void mte_suspend_exit(void);
    47	long set_mte_ctrl(struct task_struct *task, unsigned long arg);
    48	long get_mte_ctrl(struct task_struct *task);
    49	int mte_ptrace_copy_tags(struct task_struct *child, long request,
    50				 unsigned long addr, unsigned long data);
    51	
    52	void mte_assign_mem_tag_range(void *addr, size_t size);
    53	
    54	#else /* CONFIG_ARM64_MTE */
    55	
    56	/* unused if !CONFIG_ARM64_MTE, silence the compiler */
    57	#define PG_mte_tagged	0
    58	
    59	static inline void mte_sync_tags(pte_t *ptep, pte_t pte)
    60	{
    61	}
    62	static inline void mte_copy_page_tags(void *kto, const void *kfrom)
    63	{
    64	}
    65	static inline void flush_mte_state(void)
    66	{
    67	}
    68	static inline void mte_thread_switch(struct task_struct *next)
    69	{
    70	}
    71	static inline void mte_suspend_exit(void)
    72	{
    73	}
    74	static inline long set_mte_ctrl(struct task_struct *task, unsigned long arg)
    75	{
    76		return 0;
    77	}
    78	static inline long get_mte_ctrl(struct task_struct *task)
    79	{
    80		return 0;
    81	}
    82	static inline int mte_ptrace_copy_tags(struct task_struct *child,
    83					       long request, unsigned long addr,
    84					       unsigned long data)
    85	{
    86		return -EIO;
    87	}
  > 88	static inline void check_mte_async_tcf0(void)
  > 89	{
    90	}
  > 91	static inline void clear_mte_async_tcf0(void)
    92	{
    93	}
    94	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h
index 9b557a457f24..2ecb2156dac1 100644
--- a/arch/arm64/include/asm/mte.h
+++ b/arch/arm64/include/asm/mte.h
@@ -31,6 +31,8 @@  void mte_invalidate_tags(int type, pgoff_t offset);
 void mte_invalidate_tags_area(int type);
 void *mte_allocate_tag_storage(void);
 void mte_free_tag_storage(char *storage);
+void noinstr check_mte_async_tcf0(void);
+void noinstr clear_mte_async_tcf0(void);
 
 #ifdef CONFIG_ARM64_MTE
 
@@ -83,6 +85,12 @@  static inline int mte_ptrace_copy_tags(struct task_struct *child,
 {
 	return -EIO;
 }
+static inline void check_mte_async_tcf0(void)
+{
+}
+static inline void clear_mte_async_tcf0(void)
+{
+}
 
 static inline void mte_assign_mem_tag_range(void *addr, size_t size)
 {
diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index 9d3588450473..837d3624a1d5 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -289,10 +289,16 @@  asmlinkage void noinstr enter_from_user_mode(void)
 	CT_WARN_ON(ct_state() != CONTEXT_USER);
 	user_exit_irqoff();
 	trace_hardirqs_off_finish();
+
+	/* Check for asynchronous tag check faults in user space */
+	check_mte_async_tcf0();
 }
 
 asmlinkage void noinstr exit_to_user_mode(void)
 {
+	/* Ignore asynchronous tag check faults in the uaccess routines */
+	clear_mte_async_tcf0();
+
 	trace_hardirqs_on_prepare();
 	lockdep_hardirqs_on_prepare(CALLER_ADDR0);
 	user_enter_irqoff();
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index a31a0a713c85..fb57df0d453f 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -34,15 +34,11 @@ 
  * user and kernel mode.
  */
 	.macro user_exit_irqoff
-#if defined(CONFIG_CONTEXT_TRACKING) || defined(CONFIG_TRACE_IRQFLAGS)
 	bl	enter_from_user_mode
-#endif
 	.endm
 
 	.macro user_enter_irqoff
-#if defined(CONFIG_CONTEXT_TRACKING) || defined(CONFIG_TRACE_IRQFLAGS)
 	bl	exit_to_user_mode
-#endif
 	.endm
 
 	.macro	clear_gp_regs
@@ -147,32 +143,6 @@  alternative_cb_end
 .L__asm_ssbd_skip\@:
 	.endm
 
-	/* Check for MTE asynchronous tag check faults */
-	.macro check_mte_async_tcf, flgs, tmp
-#ifdef CONFIG_ARM64_MTE
-alternative_if_not ARM64_MTE
-	b	1f
-alternative_else_nop_endif
-	mrs_s	\tmp, SYS_TFSRE0_EL1
-	tbz	\tmp, #SYS_TFSR_EL1_TF0_SHIFT, 1f
-	/* Asynchronous TCF occurred for TTBR0 access, set the TI flag */
-	orr	\flgs, \flgs, #_TIF_MTE_ASYNC_FAULT
-	str	\flgs, [tsk, #TSK_TI_FLAGS]
-	msr_s	SYS_TFSRE0_EL1, xzr
-1:
-#endif
-	.endm
-
-	/* Clear the MTE asynchronous tag check faults */
-	.macro clear_mte_async_tcf
-#ifdef CONFIG_ARM64_MTE
-alternative_if ARM64_MTE
-	dsb	ish
-	msr_s	SYS_TFSRE0_EL1, xzr
-alternative_else_nop_endif
-#endif
-	.endm
-
 	.macro mte_set_gcr, tmp, tmp2
 #ifdef CONFIG_ARM64_MTE
 	/*
@@ -243,8 +213,6 @@  alternative_else_nop_endif
 	ldr	x19, [tsk, #TSK_TI_FLAGS]
 	disable_step_tsk x19, x20
 
-	/* Check for asynchronous tag check faults in user space */
-	check_mte_async_tcf x19, x22
 	apply_ssbd 1, x22, x23
 
 	ptrauth_keys_install_kernel tsk, x20, x22, x23
@@ -775,8 +743,6 @@  SYM_CODE_START_LOCAL(ret_to_user)
 	cbnz	x2, work_pending
 finish_ret_to_user:
 	user_enter_irqoff
-	/* Ignore asynchronous tag check faults in the uaccess routines */
-	clear_mte_async_tcf
 	enable_step_tsk x19, x2
 #ifdef CONFIG_GCC_PLUGIN_STACKLEAK
 	bl	stackleak_erase
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index b3c70a612c7a..84a942c25870 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -166,14 +166,43 @@  static void set_gcr_el1_excl(u64 excl)
 	 */
 }
 
-void flush_mte_state(void)
+void noinstr check_mte_async_tcf0(void)
+{
+	u64 tcf0;
+
+	if (!system_supports_mte())
+		return;
+
+	/*
+	 * dsb(ish) is not required before the register read
+	 * because the TFSRE0_EL1 is automatically synchronized
+	 * by the hardware on exception entry as SCTLR_EL1.ITFSB
+	 * is set.
+	 */
+	tcf0 = read_sysreg_s(SYS_TFSRE0_EL1);
+
+	if (tcf0 & SYS_TFSR_EL1_TF0)
+		set_thread_flag(TIF_MTE_ASYNC_FAULT);
+
+	write_sysreg_s(0, SYS_TFSRE0_EL1);
+}
+
+void noinstr clear_mte_async_tcf0(void)
 {
 	if (!system_supports_mte())
 		return;
 
-	/* clear any pending asynchronous tag fault */
 	dsb(ish);
 	write_sysreg_s(0, SYS_TFSRE0_EL1);
+}
+
+void flush_mte_state(void)
+{
+	if (!system_supports_mte())
+		return;
+
+	/* clear any pending asynchronous tag fault */
+	clear_mte_async_tcf0();
 	clear_thread_flag(TIF_MTE_ASYNC_FAULT);
 	/* disable tag checking */
 	set_sctlr_el1_tcf0(SCTLR_EL1_TCF0_NONE);