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    Subject[PATCH v3 13/17] arm64: preserve x18 when CPU is suspended
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    Don't lose the current task's shadow stack when the CPU is suspended.

    Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
    ---
    arch/arm64/include/asm/suspend.h | 2 +-
    arch/arm64/mm/proc.S | 9 +++++++++
    2 files changed, 10 insertions(+), 1 deletion(-)

    diff --git a/arch/arm64/include/asm/suspend.h b/arch/arm64/include/asm/suspend.h
    index 8939c87c4dce..0cde2f473971 100644
    --- a/arch/arm64/include/asm/suspend.h
    +++ b/arch/arm64/include/asm/suspend.h
    @@ -2,7 +2,7 @@
    #ifndef __ASM_SUSPEND_H
    #define __ASM_SUSPEND_H

    -#define NR_CTX_REGS 12
    +#define NR_CTX_REGS 13
    #define NR_CALLEE_SAVED_REGS 12

    /*
    diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
    index fdabf40a83c8..0e7c353c9dfd 100644
    --- a/arch/arm64/mm/proc.S
    +++ b/arch/arm64/mm/proc.S
    @@ -49,6 +49,8 @@
    * cpu_do_suspend - save CPU registers context
    *
    * x0: virtual address of context pointer
    + *
    + * This must be kept in sync with struct cpu_suspend_ctx in <asm/suspend.h>.
    */
    ENTRY(cpu_do_suspend)
    mrs x2, tpidr_el0
    @@ -73,6 +75,9 @@ alternative_endif
    stp x8, x9, [x0, #48]
    stp x10, x11, [x0, #64]
    stp x12, x13, [x0, #80]
    +#ifdef CONFIG_SHADOW_CALL_STACK
    + str x18, [x0, #96]
    +#endif
    ret
    ENDPROC(cpu_do_suspend)

    @@ -89,6 +94,10 @@ ENTRY(cpu_do_resume)
    ldp x9, x10, [x0, #48]
    ldp x11, x12, [x0, #64]
    ldp x13, x14, [x0, #80]
    +#ifdef CONFIG_SHADOW_CALL_STACK
    + ldr x18, [x0, #96]
    + str xzr, [x0, #96]
    +#endif
    msr tpidr_el0, x2
    msr tpidrro_el0, x3
    msr contextidr_el1, x4
    --
    2.24.0.rc0.303.g954a862665-goog
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