Unverified Commit b29a0027 authored by openeuler-ci-bot's avatar openeuler-ci-bot Committed by Gitee
Browse files

!14392 arm64: stacktrace: Handle 'lr' in interrupt context 

Merge Pull Request from: @ci-robot 
 
PR sync from: Zheng Yejian <zhengyejian1@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/OYJQWQGW6DU7WGUZJIBL2UXXW5CTD2EW/ 
 
https://gitee.com/openeuler/kernel/issues/IBEMJK 
 
Link:https://gitee.com/openeuler/kernel/pulls/14392

 

Reviewed-by: default avatarXu Kuohai <xukuohai@huawei.com>
Reviewed-by: default avatarYe Weihua <yeweihua4@huawei.com>
Reviewed-by: default avatarLi Nan <linan122@huawei.com>
Signed-off-by: default avatarLi Nan <linan122@huawei.com>
parents ac772b55 5126025c

arch/arm64/include/asm/stacktrace.h

+3 −0
Original line number Diff line number Diff line
@@ -171,4 +171,7 @@ static inline void start_backtrace(struct stackframe *frame, 
	frame->prev_type = STACK_TYPE_UNKNOWN;

}



#ifdef CONFIG_PREEMPTION

extern void preempt_schedule_irq_ret_addr(void);

#endif

#endif	/* __ASM_STACKTRACE_H */

arch/arm64/kernel/entry.S

+2 −0
Original line number Diff line number Diff line
@@ -523,6 +523,8 @@ alternative_else_nop_endif 
#endif

	cbnz	x24, 1f				// preempt count != 0 || NMI return path

	bl	arm64_preempt_schedule_irq	// irq en/disable is done inside

.global preempt_schedule_irq_ret_addr

preempt_schedule_irq_ret_addr:

1:

#endif

arch/arm64/kernel/stacktrace.c

+66 −0
Original line number Diff line number Diff line
@@ -129,6 +129,72 @@ void notrace walk_stackframe(struct task_struct *tsk, struct stackframe *frame, 


		if (!fn(data, frame->pc))

			break;

#ifdef CONFIG_PREEMPTION

		/*

		 * Suppose existing call chain: P() -> A() -> B(), B() don't construct stack

		 * frame in which fp and lr are saved for call stack unwinding, then if task1

		 * is interrupted as running at address 'B2' and then preempted by task2,

		 * and task2 unwind the call stack of task1, it expect to see P->A->B, but

		 * actually P->B, A disappeared!

		 *

		 *   A():

		 *   A1:  stp fp, lr, ...  <-- suppose fp_P and lr_P saved

		 *   A2:  mov fp, sp       <-- suppose fp_A saved in 'fp' register

		 *   A3:  bl  B            <-- call to B()

		 *   A4:  mov ...          <-- 'A4' saved in 'lr' register

		 *

		 *   B():

		 *   B1:  mov ...

		 *   B2:  mov ...   <--  interrupt comes, then run into el1_irq()

		 *   B3:  mov ...   <--  'B3' is saved in 'elr_el1' register

		 *

		 *   el1_irq():

		 *   ...          <-- save registers then construct stack frame

		 *   Cm:  bl  arm64_preempt_schedule_irq    <-- Can be preempted here

		 *   Cn:  ...

		 *

		 * In this case, at the time interrupt comes, the address 'A4' will be saved

		 * In 'lr' register, then in interrupt entry, 'lr' register will be saved in

		 * Stack memory as struct pt_regs.

		 *

		 * See following stack memory layout, as call stack unwinding, if address

		 * 'Cn' is found , we know that fp_C is point to pt_regs.stackframe[0],

		 * then we can found the 'A4' in pt_regs.regs[30], then we can know that

		 * B() is currently called by A().

		 *

		 * Stack memory (High address downto Low address):

		 *

		 *   <High address>

		 *         |-----------------|

		 *         |      lr_P       |

		 *         |-----------------|

		 *         |      fp_P       |

		 *      -> |-----------------|

		 *     |   |      ...        |

		 *     |   |-----------------|

		 *     |   |       B3        |

		 *     |   |-----------------|

		 *      -- |       fp_A      |

		 *      -> |-----------------|  <-- pt_regs.stackframe[0]

		 *     |   |                 |

		 *     |   | X0... fp lr(A4) |  <-- pt_regs.regs[]

		 *     |   |-----------------|

		 *     |   |       ...       |

		 *     |   |-----------------|

		 *     |   |        Cn       |  <-- 'Cn' is return address of

		 *     |   |-----------------|      arm64_preempt_schedule_irq()

		 *      -- |       fp_C      |

		 *         |-----------------|

		 *   <Low address>

		 */

		if (frame->pc == (unsigned long)preempt_schedule_irq_ret_addr) {

			struct pt_regs *reg = container_of((u64 *)frame->fp,

							   struct pt_regs, stackframe[0]);



			if (!fn(data, reg->regs[30]))

				break;

		}

#endif

		ret = unwind_frame(tsk, frame);

		if (ret < 0)

			break;