From: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com> To: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com>, <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org>, "James Morse" <james.morse@arm.com> Subject: Re: [PATCH v2] arm64: add the printing of tpidr_elx in __show_regs() Date: Thu, 28 Apr 2022 19:07:51 +0800 [thread overview] Message-ID: <4c956c17-6e13-37a1-7da3-b2c8243c2c01@huawei.com> (raw) In-Reply-To: <20220428102156.GA14123@willie-the-truck> 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
WARNING: multiple messages have this Message-ID (diff)
From: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com> To: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com>, <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org>, "James Morse" <james.morse@arm.com> Subject: Re: [PATCH v2] arm64: add the printing of tpidr_elx in __show_regs() Date: Thu, 28 Apr 2022 19:07:51 +0800 [thread overview] Message-ID: <4c956c17-6e13-37a1-7da3-b2c8243c2c01@huawei.com> (raw) In-Reply-To: <20220428102156.GA14123@willie-the-truck> 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 _______________________________________________ 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:[~2022-04-28 11:08 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-03-16 6:24 [PATCH v2] arm64: add the printing of tpidr_elx in __show_regs() Zhen Lei 2022-03-16 6:24 ` Zhen Lei 2022-04-27 18:40 ` Catalin Marinas 2022-04-27 18:40 ` Catalin Marinas 2022-04-28 10:23 ` Will Deacon 2022-04-28 10:23 ` Will Deacon 2022-04-28 10:21 ` Will Deacon 2022-04-28 10:21 ` Will Deacon 2022-04-28 11:07 ` Leizhen (ThunderTown) [this message] 2022-04-28 11:07 ` Leizhen (ThunderTown) 2022-04-28 12:03 ` Leizhen (ThunderTown) 2022-04-28 12:03 ` Leizhen (ThunderTown) 2022-04-28 12:10 ` Leizhen (ThunderTown) 2022-04-28 12:10 ` Leizhen (ThunderTown) 2022-04-28 13:13 ` Will Deacon 2022-04-28 13:13 ` Will Deacon 2022-04-29 4:16 ` Leizhen (ThunderTown) 2022-04-29 4:16 ` Leizhen (ThunderTown)
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