From: "H. Peter Anvin" <hpa@zytor.com>
To: "Woodhouse, David" <dwmw@amazon.co.uk>,
"peterz@infradead.org" <peterz@infradead.org>,
"kexec@lists.infradead.org" <kexec@lists.infradead.org>,
"jpoimboe@kernel.org" <jpoimboe@kernel.org>
Cc: "horms@kernel.org" <horms@kernel.org>,
"x86@kernel.org" <x86@kernel.org>, "bp@alien8.de" <bp@alien8.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"kai.huang@intel.com" <kai.huang@intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>,
"nik.borisov@suse.com" <nik.borisov@suse.com>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>
Subject: Re: [RFC PATCH 6/7] x86/kexec: Debugging support: Dump registers on exception
Date: Tue, 5 Nov 2024 14:57:28 -0800 [thread overview]
Message-ID: <3a91abd7-5edd-4f4e-bb15-fb9c91f64cc9@zytor.com> (raw)
In-Reply-To: <88c01eea-9d0f-4cac-914b-50993cbbb3ce@zytor.com>
On 11/5/24 14:27, H. Peter Anvin wrote:
>
> I don't know if it is necessary, but you can do something like this to
> make absolutely sure you don't end up with non-relative symbol references:
>
> static inline __constfunc void * sym_addr(const void *sym)
> {
> void *addr;
> asm("lea %c1(%%rip),%0" : "=r" (addr) : "i" (sym));
> return addr;
> }
>
Compiling with "-fpic -fvisibility=hidden -mcmodel=medium" can also be
used to suppress non-relative references. If you have external symbol
references they at least *should* be emitted as GOTPCRELX relocations
which the linker should relax to relative references; however, I would
think that you really don't want any of those :)
-hpa
next prev parent reply other threads:[~2024-11-05 22:57 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-03 5:35 [RFC PATCH 0/7] x86/kexec: Add exception handling for relocate_kernel David Woodhouse
2024-11-03 5:35 ` [RFC PATCH 1/7] x86/kexec: Clean up and document register use in relocate_kernel_64.S David Woodhouse
2024-11-05 10:00 ` Huang, Kai
2024-11-05 20:17 ` David Woodhouse
2024-11-03 5:35 ` [RFC PATCH 2/7] x86/kexec: Use named labels in swap_pages " David Woodhouse
2024-11-05 10:01 ` Huang, Kai
2024-11-03 5:35 ` [RFC PATCH 3/7] x86/kexec: Only swap pages for preserve_context mode David Woodhouse
2024-11-03 5:35 ` [RFC PATCH 4/7] x86/kexec: Debugging support: load a GDT David Woodhouse
2024-11-03 5:35 ` [RFC PATCH 5/7] x86/kexec: Debugging support: Load an IDT and basic exception entry points David Woodhouse
2024-11-03 5:35 ` [RFC PATCH 6/7] x86/kexec: Debugging support: Dump registers on exception David Woodhouse
2024-11-05 20:38 ` Woodhouse, David
2024-11-05 20:50 ` H. Peter Anvin
2024-11-05 21:29 ` David Woodhouse
2024-11-05 22:08 ` H. Peter Anvin
2024-11-05 21:37 ` H. Peter Anvin
2024-11-05 21:58 ` H. Peter Anvin
2024-11-05 22:27 ` H. Peter Anvin
2024-11-05 22:57 ` H. Peter Anvin [this message]
2024-11-14 7:40 ` Andy Shevchenko
2024-11-06 2:43 ` David Woodhouse
2024-11-06 2:47 ` H. Peter Anvin
2024-11-06 3:07 ` David Woodhouse
2024-11-08 5:21 ` David Woodhouse
2024-11-08 5:22 ` [RFC PATCH 1/2] x86/kexec: Use linker script for relocate_kernel page layout David Woodhouse
2024-11-08 5:22 ` [RFC PATCH 2/2] x86/kexec: Add data section to relocate_kernel David Woodhouse
2024-11-08 5:35 ` David Woodhouse
2024-11-08 11:26 ` H. Peter Anvin
2024-11-08 12:29 ` David Woodhouse
2024-11-12 8:44 ` David Woodhouse
2024-11-12 10:14 ` Peter Zijlstra
2024-11-12 10:45 ` David Woodhouse
2024-11-14 1:46 ` jpoimboe
2024-11-03 5:35 ` [RFC PATCH 7/7] [DO NOT MERGE] x86/kexec: enable DEBUG David Woodhouse
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