Messages in this thread | | | Subject | Re: [PATCH v2] arm64: add the printing of tpidr_elx in __show_regs() | From | "Leizhen (ThunderTown)" <> | Date | Thu, 28 Apr 2022 20:10:42 +0800 |
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On 2022/4/28 20:03, Leizhen (ThunderTown) wrote: > > > On 2022/4/28 19:07, Leizhen (ThunderTown) wrote: >> >> >> On 2022/4/28 18:21, Will Deacon wrote: >>> On Wed, Mar 16, 2022 at 02:24:08PM +0800, Zhen Lei wrote: >>>> Commit 7158627686f0 ("arm64: percpu: implement optimised pcpu access >>>> using tpidr_el1") and commit 6d99b68933fb ("arm64: alternatives: use >>>> tpidr_el2 on VHE hosts") use tpidr_elx to cache my_cpu_offset to optimize >>>> pcpu access. However, when performing reverse execution based on the >>>> registers and the memory contents in kdump, this information is sometimes >>>> required if there is a pcpu access. >>>> >>>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> >>>> --- >>>> arch/arm64/kernel/process.c | 11 +++++++++++ >>>> 1 file changed, 11 insertions(+) >>>> >>>> v1 --> v2: >>>> Directly print the tpidr_elx register of the current exception level. >>>> Avoid coupling with the implementation of 'my_cpu_offset'. >>>> >>>> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c >>>> index 5369e649fa79ff8..738932e6fa4e947 100644 >>>> --- a/arch/arm64/kernel/process.c >>>> +++ b/arch/arm64/kernel/process.c >>>> @@ -216,6 +216,17 @@ void __show_regs(struct pt_regs *regs) >>>> show_regs_print_info(KERN_DEFAULT); >>>> print_pstate(regs); >>>> >>>> + switch (read_sysreg(CurrentEL)) { >>> >>> This should use is_kernel_in_hyp_mode() to detect if we're running at El2. > > static inline bool is_kernel_in_hyp_mode(void) > { > return read_sysreg(CurrentEL) == CurrentEL_EL2; > } > > I think it's more intuitive to use "switch (read_sysreg(CurrentEL))". > >>> >>>> + case CurrentEL_EL1: >>>> + printk("tpidr_el1 : %016llx\n", read_sysreg(TPIDR_EL1)); >>>> + break; >>>> + case CurrentEL_EL2: >>>> + printk("tpidr_el2 : %016llx\n", read_sysreg(TPIDR_EL2)); >>>> + break; >>>> + default: >>>> + break; >>>> + } >>> >>> I think this path can be triggered directly from usermode, so we really >>> shouldn't be printing raw kernel virtual addresses here. >> >> I run echo c > /proc/sysrq-trigger and didn't trigger this path, but maybe >> there's another way. Analysis from the other side, except for the instruction >> address, all generic registers r0-r31 is output as raw. There's also an >> opportunity to contain the instruction address. > > On second thought, there seemed to be nothing wrong with it. The user need > to have capable() first. Then the address of the perpcu memory is not static,
Sorry, __my_cpu_offset is just an offset.
> the memory is dynamically allocated, exposing it is no different than exposing sp. > >> >> So how about: >> + if (oops_in_progress) >> + printk("tpidr : %016lx\n", __my_cpu_offset); >> >>> >>> Will >>> . >>> >> >
-- Regards, Zhen Lei
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