From: Dave Martin <Dave.Martin@arm.com>
To: Daniel Kiss <Daniel.Kiss@arm.com>
Cc: "kernel-team@android.com" <kernel-team@android.com>,
Szabolcs Nagy <Szabolcs.Nagy@arm.com>,
Catalin Marinas <Catalin.Marinas@arm.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Tamas Zsoldos <Tamas.Zsoldos@arm.com>,
Vincenzo Frascino <Vincenzo.Frascino@arm.com>,
Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 0/6] Fix unwinding through sigreturn trampolines
Date: Wed, 8 Jul 2020 17:57:32 +0100 [thread overview]
Message-ID: <20200708165731.GP10992@arm.com> (raw)
In-Reply-To: <EF5281FC-D14A-443F-9A28-08BD46C03FA9@arm.com>
On Mon, Jul 06, 2020 at 09:29:24AM +0000, Daniel Kiss wrote:
> Hi Ard,
>
> I like your suggestions and tuned a bit and now it works with the LLVM’s unwinders.
>
> Register 96 is out of the DWARF spec[1] and will collide with SVE registers[2] so 32 is better which is the reserved register for PC.
>
> my version:
>
> #define ARM64_SIGFRAME_REGS_OFFSET 312 /* offsetof (struct rt_sigframe, uc.uc_mcontext.regs) */
>
> .text
> .cfi_startproc
> .cfi_signal_frame
>
> .cfi_def_cfa sp, ARM64_SIGFRAME_REGS_OFFSET
> .irp x, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, \
> 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, \
> 24, 25, 26, 27, 28, 29, 30, 31
> .cfi_offset \x, \x * 8
> .endr
>
> .cfi_offset 32, 32 * 8 // regs->pc
> .cfi_return_column 32
Have you verified that this works with the GNU unwinders? I seem to
remember experimenting with .cfi_return_column in the past and hitting
problems when trying to use a fake register.
At the time I just assumed I was doing something wrong and didn't go
digging. Maybe I _was_ doing something wrong...
Cheers
---Dave
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next prev parent reply other threads:[~2020-07-08 16:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200623085436.3696-1-will@kernel.org>
[not found] ` <20200623095417.GV25945@arm.com>
[not found] ` <CAMj1kXFhCC4coSQ+Q-d3rkXFtAes6mcqMrEZr-rbO1uj+OmLCA@mail.gmail.com>
[not found] ` <20200623105827.GA3954@willie-the-truck>
[not found] ` <CAMj1kXE9_HYpD=kzpPLOir0rGGf7jWTs+S3es_0Jo3ufPuA1eQ@mail.gmail.com>
[not found] ` <07001CCE-6AF8-4491-9B3A-4FC9C1E27FDB@arm.com>
2020-06-23 15:34 ` [PATCH 0/6] Fix unwinding through sigreturn trampolines Daniel Kiss
2020-06-23 15:43 ` Ard Biesheuvel
[not found] ` <51A5A3CB-B8D1-4BAD-BC7B-0337754AEB9D@arm.com>
2020-07-06 9:29 ` Daniel Kiss
2020-07-06 9:41 ` Ard Biesheuvel
2020-07-08 16:57 ` Dave Martin [this message]
2020-07-10 17:08 ` Daniel Kiss
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