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Date: Mon, 12 Oct 2020 10:23:58 +0800 From: Xiaoming Ni <nixiaoming@...wei.com> To: Russell King - ARM Linux admin <linux@...linux.org.uk>, "Sebastian Andrzej Siewior" <bigeasy@...utronix.de> CC: <dima@...sta.com>, <will@...nel.org>, <jpoimboe@...hat.com>, <akpm@...ux-foundation.org>, <christian.brauner@...ntu.com>, <viro@...iv.linux.org.uk>, <ldufour@...ux.ibm.com>, <amanieu@...il.com>, <walken@...gle.com>, <ben.dooks@...ethink.co.uk>, <tglx@...utronix.de>, <mingo@...nel.org>, <vincent.whitchurch@...s.com>, <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>, <wangle6@...wei.com>, <luohaizheng@...wei.com> Subject: Re: [PATCH] arm:traps: Don't print stack or raw PC/LR values in backtraces On 2020/10/12 5:32, Russell King - ARM Linux admin wrote: > On Fri, Oct 09, 2020 at 10:18:20AM +0200, Sebastian Andrzej Siewior wrote: >> On 2020-10-09 09:08:50 [+0100], Russell King - ARM Linux admin wrote: >>> I am really not happy about this - it hurts at least my ability to >>> debug the kernel when people post oopses to the mailing list. If >>> people wish to make the kernel harder to debug, and are prepared >>> to be told "your kernel is undebuggable" then this patch is fine. >> >> I haven't look at the patch but don't they keep/add the representation: >> PC: symbol+offset/size >> LR: symbol+offset/size >> >> ? This is needed at very least as a replacement for the missing address. > > I don't have a problem getting rid of the hex numbers in [< >] > although then I will need to convert the symbol back to an address > using the vmlinux to then calculate its address to then find the > appropriate place in the objdump output - because objdump does > _not_ use the symbol+offset annotation. Yes, I really do look up > the numeric addresses in the objdump output to then read the > disassembly. > > $ objdump -d vmlinux | less > > and then search for the address is the fastest and most convenient > way for me rather than having to deal with some random script. > > Maybe I'm just antequated about how I do my debugging, but this > seems to me to be the most efficient and fastest way. > The loading address of the kernel module is not fixed, so symbol+offset is more useful than a hexadecimal address when the call stack contains kernel module symbols. Delete the PC/LR address and retain the sysbol+offset. The kernel can still be debugged. Thanks Xiaoming Ni
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