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[104.155.38.26]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45dda2021dfsm178871185e9.24.2025.09.09.06.10.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Sep 2025 06:10:46 -0700 (PDT) Date: Tue, 9 Sep 2025 13:10:43 +0000 From: Mostafa Saleh To: Will Deacon Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, catalin.marinas@arm.com, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, qperret@google.com, keirf@google.com Subject: Re: [PATCH 1/2] KVM: arm64: Dump instruction on hyp panic Message-ID: References: <20250717234744.2254371-1-smostafa@google.com> <20250717234744.2254371-2-smostafa@google.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Sep 08, 2025 at 01:16:45PM +0100, Will Deacon wrote: > On Thu, Jul 17, 2025 at 11:47:43PM +0000, Mostafa Saleh wrote: > > Similar to the kernel panic, where the instruction code is printed, > > we can do the same for hypervisor panics. > > > > This patch does that only in case of “CONFIG_NVHE_EL2_DEBUG” or nvhe. > > > > The next patch adds support for pKVM. > > > > Also, remove the hardcoded argument dump_kernel_instr(). > > > > Signed-off-by: Mostafa Saleh > > --- > > arch/arm64/include/asm/traps.h | 1 + > > arch/arm64/kernel/traps.c | 20 +++++++++++++------- > > arch/arm64/kvm/handle_exit.c | 5 +++++ > > 3 files changed, 19 insertions(+), 7 deletions(-) > > > > diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h > > index 82cf1f879c61..0d7e86a95d62 100644 > > --- a/arch/arm64/include/asm/traps.h > > +++ b/arch/arm64/include/asm/traps.h > > @@ -30,6 +30,7 @@ void arm64_force_sig_mceerr(int code, unsigned long far, short lsb, const char * > > void arm64_force_sig_ptrace_errno_trap(int errno, unsigned long far, const char *str); > > > > int early_brk64(unsigned long addr, unsigned long esr, struct pt_regs *regs); > > +void dump_instr(unsigned long addr); > > > > /* > > * Move regs->pc to next instruction and do necessary setup before it > > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c > > index 9bfa5c944379..d692c05e3686 100644 > > --- a/arch/arm64/kernel/traps.c > > +++ b/arch/arm64/kernel/traps.c > > @@ -149,15 +149,11 @@ pstate_check_t * const aarch32_opcode_cond_checks[16] = { > > > > int show_unhandled_signals = 0; > > > > -static void dump_kernel_instr(const char *lvl, struct pt_regs *regs) > > +void dump_instr(unsigned long addr) > > { > > - unsigned long addr = instruction_pointer(regs); > > char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str; > > int i; > > > > - if (user_mode(regs)) > > - return; > > - > > for (i = -4; i < 1; i++) { > > unsigned int val, bad; > > I'm a little worried that this function might be used to try and dump > instructions from userspace now that it just takes an address. > > Maybe we could: > > - Keep the name unchanged, e.g. void dump_kernel_instr(unsigned long kaddr) > - Inline the user_mode(regs) and instruction_pointer(regs) calls into > __die() > - Check is_ttbr1_addr(kaddr) in dump_kernel_instr() > > WDYT? Makes sense, I will do that and respin v2. Thanks, Mostafa > > Will