From: "Madhavan T. Venkataraman" <email@example.com> To: Josh Poimboeuf <firstname.lastname@example.org> Cc: email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org Subject: Re: [RFC PATCH v2 1/1] arm64: Implement stack trace termination record Date: Sat, 3 Apr 2021 23:40:51 -0500 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <firstname.lastname@example.org> On 4/3/21 10:46 PM, Madhavan T. Venkataraman wrote: >> I'm somewhat arm-ignorant, so take the following comments with a grain >> of salt. >> >> >> I don't think changing these to 'bl' is necessary, unless you wanted >> __primary_switched() and __secondary_switched() to show up in the >> stacktrace for some reason? If so, that seems like a separate patch. >> > The problem is with __secondary_switched. If you trace the code back to where > a secondary CPU is started, I don't see any calls anywhere. There are only > branches if I am not mistaken. So, the return address register never gets > set up with a proper address. The stack trace shows some hexadecimal value > instead of a symbol name. > Actually, I take that back. There are calls in that code path. But I did only see some hexadecimal value instead of a proper address in the stack trace. Sorry about that confusion. My reason to convert the branches to calls is this - the value of the return address register at that point is the return PC of the previous branch and link instruction wherever that happens to be. I think that is a little arbitrary. Instead, if I call start_kernel() and secondary_start_kernel(), the return address gets set up to the next instruction which, IMHO, is better. But I am open to other suggestions. Madhavan
next prev parent reply other threads:[~2021-04-04 4:40 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <659f3d5cc025896ba4c49aea431aa8b1abc2b741> 2021-04-02 3:24 ` [RFC PATCH v2 0/1] " madvenka 2021-04-02 3:24 ` [RFC PATCH v2 1/1] " madvenka 2021-04-03 15:59 ` Josh Poimboeuf 2021-04-04 3:46 ` Madhavan T. Venkataraman 2021-04-04 4:40 ` Madhavan T. Venkataraman [this message] 2021-04-04 16:29 ` Madhavan T. Venkataraman 2021-04-14 12:09 ` Madhavan T. Venkataraman 2021-04-16 16:17 ` Mark Brown 2021-04-16 17:31 ` Madhavan T. Venkataraman 2021-04-19 18:16 ` [RFC PATCH v2 0/1] " Madhavan T. Venkataraman 2021-04-19 18:18 ` Madhavan T. Venkataraman
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