On 5/6/21 9:12 AM, Mark Brown wrote:
> On Mon, May 03, 2021 at 12:36:14PM -0500, madvenka@xxxxxxxxxxxxxxxxxxx wrote:
>
>> There are some SYM_CODE functions that are currently in ".text" or
>> ".init.text" sections. Some of these are functions that the unwinder
>> does not care about as they are not "interesting" to livepatch. These
>> will remain in their current sections. The rest I have moved into a
>> new section called ".code.text".
>
> I was thinking it'd be good to do this by modifying SYM_CODE_START() to
> emit the section, that way nobody can forget to put any SYM_CODE into a
> special section. That does mean we'd have to first introduce a new
> variant for specifying a section that lets us override things that need
> to be in some specific section and convert everything that's in a
> special section over to that first which is a bit annoying but feels
> like it's worth it for the robustness. It'd also put some of the don't
> cares into .code.text but so long as they are actually don't cares that
> should be fine!
>
OK. I could make the section an argument to SYM_CODE*() so that a developer
will never miss that. Some documentation may be in order so the guidelines
are clear. I will do the doc patch separately, if that is alright with
you all.
About the don't car functions - most of them are OK to be moved into
.code.text. But the hypervisor vector related code has a problem. I
have not debugged that yet. If I add that code in .code.text, KVM
initialization fails in one case. In another case, when I actually
test with a VM, the VM does not come up.
I am not sure. But it looks like there may be some reloc issue going on.
I don't have a handle on this yet. So, for now, I will leave the hypervisor
stuff in .text. But I will mark it as TBD in the cover letter so we don't
lose track of it.
>> Don't care functions
>> ====================
>
> We also have a bunch of things like __cpu_soft_restart which don't seem
> to be called out here but need to be in .idmap.text.
>
It is already in .idmap.text.
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* CPU reset routines
*
* Copyright (C) 2001 Deep Blue Solutions Ltd.
* Copyright (C) 2012 ARM Ltd.
* Copyright (C) 2015 Huawei Futurewei Technologies.
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/sysreg.h>
#include <asm/virt.h>
.text
.pushsection .idmap.text, "awx"
/*
* __cpu_soft_restart(el2_switch, entry, arg0, arg1, arg2) - Helper for
* cpu_soft_restart.
*
* @el2_switch: Flag to indicate a switch to EL2 is needed.
* @entry: Location to jump to for soft reset.
* arg0: First argument passed to @entry. (relocation list)
* arg1: Second argument passed to @entry.(physical kernel entry)
* arg2: Third argument passed to @entry. (physical dtb address)
*
* Put the CPU into the same state as it would be if it had been reset, and
* branch to what would be the reset vector. It must be executed with the
* flat identity mapping.
*/
SYM_CODE_START(__cpu_soft_restart)
mov_q x12, INIT_SCTLR_EL1_MMU_OFF
pre_disable_mmu_workaround
/*
* either disable EL1&0 translation regime or disable EL2&0 translation
* regime if HCR_EL2.E2H == 1
*/
msr sctlr_el1, x12
isb
cbz x0, 1f // el2_switch?
mov x0, #HVC_SOFT_RESTART
hvc #0 // no return
1: mov x8, x1 // entry
mov x0, x2 // arg0
mov x1, x3 // arg1
mov x2, x4 // arg2
br x8
SYM_CODE_END(__cpu_soft_restart)
.popsection
I will double check all the *.S files and make sure that every function is accounted
for in version 4.
Stay tuned.
Thanks.
Madhavan
