enable_step_tsk may enable single-step, so needs to mask debug exceptions to prevent us from single-stepping kernel_exit. This should be the callers problem.
Earlier cleanup (2a2830703a23) moved disable_step_tsk into kernel_entry. enable_step_tsk has two callers, both immediately before kernel_exit 0. Move the macro call into kernel_exit after local_mask_daif. enable_step_tsk is now only called with debug exceptions masked. This was the last user of disable_dbg, remove it. Signed-off-by: James Morse <[email protected]> --- arch/arm64/include/asm/assembler.h | 9 +-------- arch/arm64/kernel/entry.S | 7 ++++--- 2 files changed, 5 insertions(+), 11 deletions(-) diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index 896ddd9b21a6..f4dc435406ea 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -70,13 +70,6 @@ msr daif, \flags .endm -/* - * Enable and disable debug exceptions. - */ - .macro disable_dbg - msr daifset, #8 - .endm - .macro enable_dbg msr daifclr, #8 .endm @@ -90,9 +83,9 @@ 9990: .endm + /* call with debug exceptions masked */ .macro enable_step_tsk, flgs, tmp tbz \flgs, #TIF_SINGLESTEP, 9990f - disable_dbg mrs \tmp, mdscr_el1 orr \tmp, \tmp, #1 msr mdscr_el1, \tmp diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 491182f0abb5..0836b65d4c84 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -212,6 +212,10 @@ alternative_else_nop_endif .if \el == 0 ldr x23, [sp, #S_SP] // load return stack pointer msr sp_el0, x23 + + ldr x1, [tsk, #TSK_TI_FLAGS] + enable_step_tsk flgs=x1, tmp=x2 + #ifdef CONFIG_ARM64_ERRATUM_845719 alternative_if ARM64_WORKAROUND_845719 tbz x22, #4, 1f @@ -750,7 +754,6 @@ ret_fast_syscall: cbnz x2, ret_fast_syscall_trace and x2, x1, #_TIF_WORK_MASK cbnz x2, work_pending - enable_step_tsk x1, x2 kernel_exit 0 ret_fast_syscall_trace: enable_irq // enable interrupts @@ -765,7 +768,6 @@ work_pending: #ifdef CONFIG_TRACE_IRQFLAGS bl trace_hardirqs_on // enabled while in userspace #endif - ldr x1, [tsk, #TSK_TI_FLAGS] // re-check for single-step b finish_ret_to_user /* * "slow" syscall return path. @@ -776,7 +778,6 @@ ret_to_user: and x2, x1, #_TIF_WORK_MASK cbnz x2, work_pending finish_ret_to_user: - enable_step_tsk x1, x2 kernel_exit 0 ENDPROC(ret_to_user) -- 2.13.2 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
