From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: David Laight <David.Laight@aculab.com>, Ard Biesheuvel <ardb@kernel.org>
Cc: 'Jiangfeng Xiao' <xiaojiangfeng@huawei.com>,
"arnd@arndb.de" <arnd@arndb.de>,
"keescook@chromium.org" <keescook@chromium.org>,
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"angelogioacchino.delregno@collabora.com"
<angelogioacchino.delregno@collabora.com>,
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"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
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"jpoimboe@kernel.org" <jpoimboe@kernel.org>,
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Subject: Re: [PATCH v2] ARM: unwind: improve unwinders for noreturn case
Date: Thu, 21 Mar 2024 11:23:51 +0000 [thread overview]
Message-ID: <ZfwYx/8k8FVONg6+@shell.armlinux.org.uk> (raw)
In-Reply-To: <bbcca1e205384cf0b42236e17f3969f7@AcuMS.aculab.com>
On Thu, Mar 21, 2024 at 10:22:30AM +0000, David Laight wrote:
> How aggressively does the compiler optimise 'noreturn' functions?
I've seen cases where the compiler emits a BL instruction as the very
last thing in the function, and nothing after it.
This is where the problem lies - because the link register value
created by the BL instruction will point to the instruction after the
BL which will _not_ part of the function that invoked the BL. That
will probably cause issues for the ELF unwinder, which means this
issue probably goes beyond _just_ printing the function name.
I have vague memories that Ard has been involved in the unwinder,
maybe he could comment on this problem? Maybe we need the unwinder
itself to do the correction? I also wonder whether we should only
do the correction if we detect that we're pointing at the first
instruction of a function, and the previous instruction in the
text segment was a BL.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
next prev parent reply other threads:[~2024-03-21 11:24 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-04 1:39 [PATCH] usercopy: delete __noreturn from usercopy_abort Jiangfeng Xiao
2024-03-04 15:15 ` Jann Horn
2024-03-04 17:40 ` Kees Cook
2024-03-05 3:31 ` Jiangfeng Xiao
2024-03-05 9:32 ` Kees Cook
2024-03-05 11:38 ` Jiangfeng Xiao
2024-03-05 17:58 ` Josh Poimboeuf
2024-03-06 4:00 ` Jiangfeng Xiao
2024-03-06 9:52 ` Russell King (Oracle)
2024-03-06 16:02 ` Josh Poimboeuf
2024-03-09 14:58 ` David Laight
2024-03-18 4:01 ` Jiangfeng Xiao
2024-03-05 2:54 ` Jiangfeng Xiao
2024-03-05 3:12 ` Jiangfeng Xiao
2024-03-20 2:19 ` [PATCH] ARM: unwind: improve unwinders for noreturn case Jiangfeng Xiao
2024-03-20 2:46 ` Kees Cook
2024-03-20 3:30 ` Jiangfeng Xiao
2024-03-20 3:34 ` Matthew Wilcox
2024-03-20 3:46 ` Jiangfeng Xiao
2024-03-20 3:44 ` [PATCH v2] " Jiangfeng Xiao
2024-03-20 8:45 ` Russell King (Oracle)
2024-03-20 15:30 ` Jiangfeng Xiao
2024-03-20 19:40 ` Russell King (Oracle)
2024-03-21 9:44 ` Jiangfeng Xiao
2024-03-21 10:22 ` David Laight
2024-03-21 11:23 ` Russell King (Oracle) [this message]
2024-03-21 12:07 ` David Laight
2024-03-21 12:22 ` Russell King (Oracle)
2024-03-21 12:57 ` David Laight
2024-03-21 13:08 ` Russell King (Oracle)
2024-03-21 14:37 ` David Laight
2024-03-21 14:56 ` Russell King (Oracle)
2024-03-21 15:20 ` David Laight
2024-03-21 15:33 ` Russell King (Oracle)
2024-03-21 22:43 ` Ard Biesheuvel
2024-03-22 0:08 ` Russell King (Oracle)
2024-03-22 9:24 ` David Laight
2024-03-22 9:52 ` Russell King (Oracle)
2024-03-22 12:54 ` Jiangfeng Xiao
2024-03-22 14:16 ` David Laight
2024-03-20 15:41 ` [PATCH v3] " Jiangfeng Xiao
2024-03-20 19:42 ` Russell King (Oracle)
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