diff options
| author | Sumit Garg <sumit.garg@linaro.org> | 2023-02-02 08:31:48 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2023-04-14 14:39:47 +0200 |
| commit | af6c0bd59f4f3ad5daad2f7b777954b1954551d5 (patch) | |
| tree | d6e85e28e55c25fcf524f98d0f3f7eb6a6c23561 /arch/arm64/kernel/debug-monitors.c | |
| parent | arm64/sme: Fix some comments of ARM SME (diff) | |
| download | linux-af6c0bd59f4f3ad5daad2f7b777954b1954551d5.tar.xz linux-af6c0bd59f4f3ad5daad2f7b777954b1954551d5.zip | |
arm64: kgdb: Set PSTATE.SS to 1 to re-enable single-step
Currently only the first attempt to single-step has any effect. After
that all further stepping remains "stuck" at the same program counter
value.
Refer to the ARM Architecture Reference Manual (ARM DDI 0487E.a) D2.12,
PSTATE.SS=1 should be set at each step before transferring the PE to the
'Active-not-pending' state. The problem here is PSTATE.SS=1 is not set
since the second single-step.
After the first single-step, the PE transferes to the 'Inactive' state,
with PSTATE.SS=0 and MDSCR.SS=1, thus PSTATE.SS won't be set to 1 due to
kernel_active_single_step()=true. Then the PE transferes to the
'Active-pending' state when ERET and returns to the debugger by step
exception.
Before this patch:
==================
Entering kdb (current=0xffff3376039f0000, pid 1) on processor 0 due to Keyboard Entry
[0]kdb>
[0]kdb>
[0]kdb> bp write_sysrq_trigger
Instruction(i) BP #0 at 0xffffa45c13d09290 (write_sysrq_trigger)
is enabled addr at ffffa45c13d09290, hardtype=0 installed=0
[0]kdb> go
$ echo h > /proc/sysrq-trigger
Entering kdb (current=0xffff4f7e453f8000, pid 175) on processor 1 due to Breakpoint @ 0xffffad651a309290
[1]kdb> ss
Entering kdb (current=0xffff4f7e453f8000, pid 175) on processor 1 due to SS trap @ 0xffffad651a309294
[1]kdb> ss
Entering kdb (current=0xffff4f7e453f8000, pid 175) on processor 1 due to SS trap @ 0xffffad651a309294
[1]kdb>
After this patch:
=================
Entering kdb (current=0xffff6851c39f0000, pid 1) on processor 0 due to Keyboard Entry
[0]kdb> bp write_sysrq_trigger
Instruction(i) BP #0 at 0xffffc02d2dd09290 (write_sysrq_trigger)
is enabled addr at ffffc02d2dd09290, hardtype=0 installed=0
[0]kdb> go
$ echo h > /proc/sysrq-trigger
Entering kdb (current=0xffff6851c53c1840, pid 174) on processor 1 due to Breakpoint @ 0xffffc02d2dd09290
[1]kdb> ss
Entering kdb (current=0xffff6851c53c1840, pid 174) on processor 1 due to SS trap @ 0xffffc02d2dd09294
[1]kdb> ss
Entering kdb (current=0xffff6851c53c1840, pid 174) on processor 1 due to SS trap @ 0xffffc02d2dd09298
[1]kdb> ss
Entering kdb (current=0xffff6851c53c1840, pid 174) on processor 1 due to SS trap @ 0xffffc02d2dd0929c
[1]kdb>
Fixes: 44679a4f142b ("arm64: KGDB: Add step debugging support")
Co-developed-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20230202073148.657746-3-sumit.garg@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel/debug-monitors.c')
| -rw-r--r-- | arch/arm64/kernel/debug-monitors.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index 3da09778267e..64f2ecbdfe5c 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -438,6 +438,11 @@ int kernel_active_single_step(void) } NOKPROBE_SYMBOL(kernel_active_single_step); +void kernel_rewind_single_step(struct pt_regs *regs) +{ + set_regs_spsr_ss(regs); +} + /* ptrace API */ void user_enable_single_step(struct task_struct *task) { |