Commit 47abaacd authored by Mark Rutland's avatar Mark Rutland Committed by Zheng Zengkai
Browse files

arm64: Snapshot thread flags 

mainline inclusion
from mainline-v5.17-rc1
commit 342b3808
category: performance
bugzilla: https://gitee.com/openeuler/kernel/issues/IA5WFA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=342b3808786518ced347f40b59bae68664e20007



----------------------------------------------------------------------

Some thread flags can be set remotely, and so even when IRQs are disabled,
the flags can change under our feet. Generally this is unlikely to cause a
problem in practice, but it is somewhat unsound, and KCSAN will
legitimately warn that there is a data race.

To avoid such issues, a snapshot of the flags has to be taken prior to
using them. Some places already use READ_ONCE() for that, others do not.

Convert them all to the new flag accessor helpers.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarWill Deacon <will@kernel.org>
Acked-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20211129130653.2037928-7-mark.rutland@arm.com



Conflict:
	arch/arm64/kernel/entry-common.c

Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent ace27e12

arch/arm64/kernel/ptrace.c

+2 −2
Original line number Diff line number Diff line
@@ -2098,7 +2098,7 @@ static void tracehook_report_syscall(struct pt_regs *regs, 


int syscall_trace_enter(struct pt_regs *regs)

{

	unsigned long flags = READ_ONCE(current_thread_info()->flags);

	unsigned long flags = read_thread_flags();



	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {

		tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
@@ -2121,7 +2121,7 @@ int syscall_trace_enter(struct pt_regs *regs) 


void syscall_trace_exit(struct pt_regs *regs)

{

	unsigned long flags = READ_ONCE(current_thread_info()->flags);

	unsigned long flags = read_thread_flags();



	audit_syscall_exit(regs);

arch/arm64/kernel/signal.c

+1 −1
Original line number Diff line number Diff line
@@ -891,7 +891,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, 
		}



		local_daif_mask();

		thread_flags = READ_ONCE(current_thread_info()->flags);

		thread_flags = read_thread_flags();

	} while (thread_flags & _TIF_WORK_MASK);

}

arch/arm64/kernel/syscall.c

+2 −2
Original line number Diff line number Diff line
@@ -109,7 +109,7 @@ static void cortex_a76_erratum_1463225_svc_handler(void) { } 
static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,

			   const syscall_fn_t syscall_table[])

{

	unsigned long flags = current_thread_info()->flags;

	unsigned long flags = read_thread_flags();



	regs->orig_x0 = regs->regs[0];

	regs->syscallno = scno;
@@ -177,7 +177,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, 
	 */

	if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {

		local_daif_mask();

		flags = current_thread_info()->flags;

		flags = read_thread_flags();

		if (!has_syscall_work(flags) && !(flags & _TIF_SINGLESTEP))

			return;

		local_daif_restore(DAIF_PROCCTX);