From: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com> To: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v3] arm64: add the printing of tpidr_elx in __show_regs() Date: Fri, 6 May 2022 18:21:37 +0800 [thread overview] Message-ID: <cc8180ee-1c17-aab4-c883-4f8794edceb5@huawei.com> (raw) In-Reply-To: <YnTz6oFEQGDBrIpi@FVFF77S0Q05N> On 2022/5/6 18:09, Mark Rutland wrote: > On Fri, May 06, 2022 at 04:16:55PM +0800, Leizhen (ThunderTown) wrote: >> >> >> On 2022/5/5 21:34, Leizhen (ThunderTown) wrote: >>> On 2022/5/5 21:26, Leizhen (ThunderTown) wrote: >>>> On 2022/5/5 21:04, Mark Rutland wrote: >>>>> On Thu, May 05, 2022 at 05:56:40PM +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 | 5 +++++ >>>>>> 1 file changed, 5 insertions(+) >>>>>> >>>>>> v2 --> v3: >>>>>> 1) Relace "switch (read_sysreg(CurrentEL))" statement with >>>>>> "if (is_kernel_in_hyp_mode())" statement. >>>>>> 2) Change the register name to lowercase. >>>>>> >>>>>> 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 7fa97df55e3ad3f..7b6bccce9721c36 100644 >>>>>> --- a/arch/arm64/kernel/process.c >>>>>> +++ b/arch/arm64/kernel/process.c >>>>>> @@ -216,6 +216,11 @@ void __show_regs(struct pt_regs *regs) >>>>>> show_regs_print_info(KERN_DEFAULT); >>>>>> print_pstate(regs); >>>>>> >>>>>> + if (is_kernel_in_hyp_mode()) >>>>>> + printk("tpidr_el2 : %016llx\n", read_sysreg(tpidr_el2)); >>>>>> + else >>>>>> + printk("tpidr_el1 : %016llx\n", read_sysreg(tpidr_el1)); >>>>> >>>>> If we care about the offset specifically, this would be simpler as: >>>>> >>>>> printk("cpu offset : 0x%016lx\n", __my_cpu_offset()); >>>> >>>> The function name is __show_regs(), so not using register name may not be good. >>>> In fact, some other architectures may also have this problem. If we use my_cpu_offset, >>>> we may need to put it in a public. >>> >>> The other idea is to back up each my_cpu_offset in an array. In this way, the offset can >>> be queried through vmcore even if it is not printed. >> >> Sorry, __per_cpu_offset[NR_CPUS] is always defined. > > Surely that's in the vmcore already? It's just data in memory. Yes. There is also a definition in drivers/base/arch_numa.c. I didn't search the drivers directory at first. I thought there would be no definition when CONFIG_HAVE_SETUP_PER_CPU_AREA=y. crash> p -x __per_cpu_offset __per_cpu_offset = $1 = {0xffff8003f460d000, 0xffff8003f4621000, 0xffff8003f4635000, 0xffff8003f4649000 > > Thanks, > Mark. > . > -- Regards, Zhen Lei
WARNING: multiple messages have this Message-ID (diff)
From: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com> To: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v3] arm64: add the printing of tpidr_elx in __show_regs() Date: Fri, 6 May 2022 18:21:37 +0800 [thread overview] Message-ID: <cc8180ee-1c17-aab4-c883-4f8794edceb5@huawei.com> (raw) In-Reply-To: <YnTz6oFEQGDBrIpi@FVFF77S0Q05N> On 2022/5/6 18:09, Mark Rutland wrote: > On Fri, May 06, 2022 at 04:16:55PM +0800, Leizhen (ThunderTown) wrote: >> >> >> On 2022/5/5 21:34, Leizhen (ThunderTown) wrote: >>> On 2022/5/5 21:26, Leizhen (ThunderTown) wrote: >>>> On 2022/5/5 21:04, Mark Rutland wrote: >>>>> On Thu, May 05, 2022 at 05:56:40PM +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 | 5 +++++ >>>>>> 1 file changed, 5 insertions(+) >>>>>> >>>>>> v2 --> v3: >>>>>> 1) Relace "switch (read_sysreg(CurrentEL))" statement with >>>>>> "if (is_kernel_in_hyp_mode())" statement. >>>>>> 2) Change the register name to lowercase. >>>>>> >>>>>> 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 7fa97df55e3ad3f..7b6bccce9721c36 100644 >>>>>> --- a/arch/arm64/kernel/process.c >>>>>> +++ b/arch/arm64/kernel/process.c >>>>>> @@ -216,6 +216,11 @@ void __show_regs(struct pt_regs *regs) >>>>>> show_regs_print_info(KERN_DEFAULT); >>>>>> print_pstate(regs); >>>>>> >>>>>> + if (is_kernel_in_hyp_mode()) >>>>>> + printk("tpidr_el2 : %016llx\n", read_sysreg(tpidr_el2)); >>>>>> + else >>>>>> + printk("tpidr_el1 : %016llx\n", read_sysreg(tpidr_el1)); >>>>> >>>>> If we care about the offset specifically, this would be simpler as: >>>>> >>>>> printk("cpu offset : 0x%016lx\n", __my_cpu_offset()); >>>> >>>> The function name is __show_regs(), so not using register name may not be good. >>>> In fact, some other architectures may also have this problem. If we use my_cpu_offset, >>>> we may need to put it in a public. >>> >>> The other idea is to back up each my_cpu_offset in an array. In this way, the offset can >>> be queried through vmcore even if it is not printed. >> >> Sorry, __per_cpu_offset[NR_CPUS] is always defined. > > Surely that's in the vmcore already? It's just data in memory. Yes. There is also a definition in drivers/base/arch_numa.c. I didn't search the drivers directory at first. I thought there would be no definition when CONFIG_HAVE_SETUP_PER_CPU_AREA=y. crash> p -x __per_cpu_offset __per_cpu_offset = $1 = {0xffff8003f460d000, 0xffff8003f4621000, 0xffff8003f4635000, 0xffff8003f4649000 > > Thanks, > Mark. > . > -- Regards, Zhen Lei _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-05-06 10:22 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-05-05 9:56 [PATCH v3] arm64: add the printing of tpidr_elx in __show_regs() Zhen Lei 2022-05-05 9:56 ` Zhen Lei 2022-05-05 10:51 ` Will Deacon 2022-05-05 10:51 ` Will Deacon 2022-05-05 13:04 ` Mark Rutland 2022-05-05 13:04 ` Mark Rutland 2022-05-05 13:26 ` Leizhen (ThunderTown) 2022-05-05 13:26 ` Leizhen (ThunderTown) 2022-05-05 13:34 ` Leizhen (ThunderTown) 2022-05-05 13:34 ` Leizhen (ThunderTown) 2022-05-06 8:16 ` Leizhen (ThunderTown) 2022-05-06 8:16 ` Leizhen (ThunderTown) 2022-05-06 10:09 ` Mark Rutland 2022-05-06 10:09 ` Mark Rutland 2022-05-06 10:21 ` Leizhen (ThunderTown) [this message] 2022-05-06 10:21 ` Leizhen (ThunderTown)
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