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Message-ID: <854eef54-4779-4233-a958-0c98ae5fcb7e@csgroup.eu>
Date: Fri, 13 Sep 2024 10:30:56 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Luming Yu <luming.yu@...ngroup.cn>
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
mpe@...erman.id.au, npiggin@...il.com, jialong.yang@...ngroup.cn,
luming.yu@...il.com
Subject: Re: [PATCH 1/2] powerpc/entry: convert to common and generic entry
Le 13/09/2024 à 09:38, Luming Yu a écrit :
> On Fri, Sep 13, 2024 at 08:54:12AM +0200, Christophe Leroy wrote:
>>
>>
>> Le 13/09/2024 à 03:40, Luming Yu a écrit :
>>> On Thu, Sep 12, 2024 at 12:23:29PM +0200, Christophe Leroy wrote:
>>>>
>>>>
>>>> Le 12/09/2024 à 10:24, Luming Yu a écrit :
>>>>> From: Yu Luming <luming.yu@...il.com>
>>>>>
>>>>> convert powerpc entry code in syscall and fault to use syscall_work
>>>>> and irqentry_state as well as common calls from generic entry infrastructure.
>>>>>
>>>>> Signed-off-by: Luming Yu <luming.yu@...ngroup.cn>
>>>>> ---
>>>>> arch/powerpc/Kconfig | 1 +
>>>>> arch/powerpc/include/asm/hw_irq.h | 5 +++++
>>>>> arch/powerpc/include/asm/processor.h | 6 ++++++
>>>>> arch/powerpc/include/asm/syscall.h | 5 +++++
>>>>> arch/powerpc/include/asm/thread_info.h | 1 +
>>>>> arch/powerpc/kernel/syscall.c | 6 +++++-
>>>>> arch/powerpc/mm/fault.c | 5 +++++
>>>>> 7 files changed, 28 insertions(+), 1 deletion(-)
>>>>
>>>> There is another build problem:
>>>>
>>>> CC kernel/entry/common.o
>>>> kernel/entry/common.c: In function 'irqentry_exit':
>>>> kernel/entry/common.c:335:21: error: implicit declaration of function
>>>> 'regs_irqs_disabled'; did you mean 'raw_irqs_disabled'?
>>>> [-Werror=implicit-function-declaration]
>>>> 335 | } else if (!regs_irqs_disabled(regs)) {
>>>> | ^~~~~~~~~~~~~~~~~~
>>>> | raw_irqs_disabled
>>>>
>>>>
>>>> You have put regs_irqs_disabled() in a section dedicated to PPC64, so it
>>>> fails on PPC32.
>>>>
>>>>
>>>> After fixing this problem and providing an empty asm/entry-common.h it is
>>>> now possible to build the kernel. But that's not enough, the board is stuck
>>>> after:
>>>>
>>>> ...
>>>> [ 2.871391] Freeing unused kernel image (initmem) memory: 1228K
>>>> [ 2.877990] Run /init as init process
>>>
>>> Thanks for these questions. :-)
>>> I haven't gotten chance to run it in ppc32 qemu.
>>> the common syscall trace enter lost this hunk
>>> - if (!is_32bit_task())
>>> - audit_syscall_entry(regs->gpr[0], regs->gpr[3], regs->gpr[4],
>>> - regs->gpr[5], regs->gpr[6]);
>>> - else
>>> - audit_syscall_entry(regs->gpr[0],
>>> - regs->gpr[3] & 0xffffffff,
>>> - regs->gpr[4] & 0xffffffff,
>>> - regs->gpr[5] & 0xffffffff,
>>> - regs->gpr[6] & 0xffffffff);
>>> which I don't understand whether we need a arch callbacks for it.
>>
>> I don't thing so.
>>
>> As far as I can see, audit_syscall_entry() is called by
>> syscall_enter_audit() in kernel/entry/common.c
>>
>> And the masking of arguments based on is_32bit_task() is done in
>> syscall_get_arguments() with is called by
>> syscall_enter_audit() just before calling audit_syscall_entry() and which is
>> an arch callback that does the same as the removed hunk.
> so, syscall_get_arguments is the ppc arch callback. thanks. :-)
>>>
>>> Before I sent out the RFC patch set, the very limited compile and boot test goes well with a ppc64 qemu VM. Surely, there will be a lot of test, debug and following up patch set update that is necessary to make it a complete convert.
>>
>> Even on ppc64 it doesn't build, at the first place because
>> arch/powerpc/include/asm/entry-common.h is missing in your patch. Did you
>> forget to 'git add' it ?
> oh, I forget that I was testing this patch on top of the early user notifier patch:
> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Flinuxppc%2Fissues%2Fissues%2F477&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C35a08ca9a81f4c6ff8ce08dcd3c73555%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638618099770810941%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=yCQWLIAXL%2BNHnzrh0e91WIBvF0c5WfF6pY6ZMHstocA%3D&reserved=0, https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork.ozlabs.org%2Fproject%2Flinuxppc-dev%2Fpatch%2F1FD36D52828D2506%2B20231218031309.2063-1-luming.yu%40shingroup.cn%2F&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C35a08ca9a81f4c6ff8ce08dcd3c73555%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638618099770819779%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=0WBSUlpAbL6EMdPEAtJv1HUHkbeUjjUcP98wYf9IxM4%3D&reserved=0
> and the entry-common.h is as follows:
> [root@...alhost linux]# cat arch/powerpc/include/asm/entry-common.h
> /* SPDX-License-Identifier: GPL-2.0 */
> #ifndef ARCH_POWERPC_ENTRY_COMMON_H
> #define ARCH_POWERPC_ENTRY_COMMON_H
>
> #include <linux/user-return-notifier.h>
>
> static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
> unsigned long ti_work)
> {
> if (ti_work & _TIF_USER_RETURN_NOTIFY)
> fire_user_return_notifiers();
> }
>
> #define arch_exit_to_user_mode_prepare arch_exit_to_user_mode_prepare
>
> #endif
>
> As you could see , it looks irrelevant.
>>
>> And same as with PPC32, when I build PPC64 with an empty asm/entry-common.h,
>> it doesn't work. So, I guess you had some needed code in that file and you
>> have to send it.
>
> please send me your kernel config and let me reproduce and double check
> if there could be another bit of code make the difference. My test p8 64bit VM boots
> an unmodified fedora 38 user space just fine with the patch.
> After boot, the only difference is make install of kernel could hang for a while, that
> I'm not sure how that could happen yet. and I plan to do some unit test for many common
> features like : lockdep, ptrace, rcu, audit...
>>
>
I tested with both ppc64_defconfig and ppc64le_defconfig. With those two
configs QEMU remains stuck after the following lines. I use QEMU with
machine pseries:
[ 2.701874][ T1] Running code patching self-tests ...
[ 2.734007][ T1] registered taskstats version 1
[ 2.735891][ T1] Loading compiled-in X.509 certificates
[ 2.756472][ T1] Loaded X.509 cert 'Build time autogenerated
kernel key: 003f25410c2285abf44b4685b6d63682a2dc9f11'
[ 2.784474][ T1] Demotion targets for Node 0: null
[ 2.784748][ T1] page_owner is disabled
[ 2.786795][ T1] Secure boot mode disabled
[ 2.787436][ T1] ima: No TPM chip found, activating TPM-bypass!
[ 2.787568][ T1] Loading compiled-in module X.509 certificates
[ 2.790854][ T1] Loaded X.509 cert 'Build time autogenerated
kernel key: 003f25410c2285abf44b4685b6d63682a2dc9f11'
[ 2.791289][ T1] ima: Allocated hash algorithm: sha256
[ 2.796260][ T1] Secure boot mode disabled
[ 2.796448][ T1] Trusted boot mode disabled
[ 2.796560][ T1] ima: No architecture policies found
[ 2.799580][ T1] printk: legacy console [netcon0] enabled
[ 2.799696][ T1] netconsole: network logging started
[ 2.880282][ T1] Freeing unused kernel image (initmem) memory: 6528K
[ 2.884618][ T1] Checked W+X mappings: passed, no W+X pages found
[ 2.885366][ T1] rodata_test: all tests were successful
[ 2.885749][ T1] Run /init as init process
[ 3.214730][ T58] mount (58) used greatest stack depth: 28672 bytes
left
...
nothing happens after that.
For PPC32 I use pmac32_defconfig and QEMU machine mac99
Christophe
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