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Revert "arm64: Stash shadow stack pointer in the task struct on interrupt"

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This reverts commit 3f225f29c6 which is
commit 59b37fe52f49955791a460752c37145f1afdcad1 upstream.

The shadow call stack for irq now is stored in current task's thread info
in irq_stack_entry. There is a possibility that we have some soft irqs
pending at the end of hard irq, and when we process softirq with the irq
enabled, irq_stack_entry will enter again and overwrite the shadow call
stack whitch stored in current task's thread info, leading to the
incorrect shadow call stack restoration for the first entry of the hard
IRQ, then the system end up with a panic.

task A                               |  task A
-------------------------------------+------------------------------------
el1_irq        //irq1 enter          |
  irq_handler  //save scs_sp1        |
    gic_handle_irq                   |
    irq_exit                         |
      __do_softirq                   |
                                     | el1_irq         //irq2 enter
                                     |   irq_handler   //save scs_sp2
                                     |                 //overwrite scs_sp1
                                     |   ...
                                     |   irq_stack_exit //restore scs_sp2
  irq_stack_exit //restore wrong     |
                 //scs_sp2           |

So revert this commit to fix it.

Fixes: 3f225f29c6 ("arm64: Stash shadow stack pointer in the task struct on interrupt")
Signed-off-by: Xiang Yang <xiangyang3@huawei.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Xiang Yang 2024-02-19 21:21:53 +08:00 committed by Greg Kroah-Hartman
parent 70ca0dbae4
commit f7e0231eea
1 changed files with 6 additions and 2 deletions
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8
arch/arm64/kernel/entry.S
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@ -431,7 +431,9 @@ SYM_CODE_END(__swpan_exit_el0)
.macro irq_stack_entry
mov x19, sp // preserve the original sp
scs_save tsk // preserve the original shadow stack
#ifdef CONFIG_SHADOW_CALL_STACK
mov x24, scs_sp // preserve the original shadow stack
#endif
/*
* Compare sp with the base of the task stack.
@ -465,7 +467,9 @@ SYM_CODE_END(__swpan_exit_el0)
*/
.macro irq_stack_exit
mov sp, x19
scs_load_current
#ifdef CONFIG_SHADOW_CALL_STACK
mov scs_sp, x24
#endif
.endm
/* GPRs used by entry code */