linux-kernel - [PATCH v2] arm64: add the printing of tpidr_elx in __show

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Date:   Wed, 16 Mar 2022 14:24:08 +0800
From:   Zhen Lei <thunder.leizhen@...wei.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
CC:     Zhen Lei <thunder.leizhen@...wei.com>,
        James Morse <james.morse@....com>
Subject: [PATCH v2] arm64: add the printing of tpidr_elx in __show_regs()

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@...wei.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)) {
+	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;
+	}
+
 	if (!user_mode(regs)) {
 		printk("pc : %pS\n", (void *)regs->pc);
 		printk("lr : %pS\n", (void *)ptrauth_strip_insn_pac(lr));
-- 
2.25.1