From: "Madhavan T. Venkataraman" <firstname.lastname@example.org> To: Josh Poimboeuf <email@example.com> Cc: 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, email@example.com Subject: Re: [RFC PATCH v2 1/1] arm64: Implement stack trace termination record Date: Sun, 4 Apr 2021 11:29:57 -0500 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) In-Reply-To: <email@example.com> On 4/3/21 11:40 PM, Madhavan T. Venkataraman wrote: > > > 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. > Again, I apologize. I had this confused with something else in my notes. So, the stack trace looks like this without my changes to convert the branch to secondary_start_kernel() to a call: ... [ 0.022492] secondary_start_kernel+0x188/0x1e0 [ 0.022503] 0xf8689e1cc It looks like the code calls __enable_mmu before reaching the place where it branches to secondary_start_kernel(). bl __enable_mmu The return address register should be set to the next instruction address. I am guessing that the return address is 0xf8689e1cc because of the idmap stuff. Madhavan
next prev parent reply other threads:[~2021-04-04 16:30 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 2021-04-04 16:29 ` Madhavan T. Venkataraman [this message] 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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