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 19:07:51 +0800 |
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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. > >> + 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.
So how about: + if (oops_in_progress) + printk("tpidr : %016lx\n", __my_cpu_offset);
> > Will > . >
-- Regards, Zhen Lei
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