From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Guenter Roeck <linux@roeck-us.net>
Cc: "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Paul Mackerras <paulus@samba.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 3/4] powerpc/code-patching: Use jump_label for testing freed initmem
Date: Thu, 19 May 2022 06:27:40 +0000 [thread overview]
Message-ID: <ab09a24a-acca-a5a8-2e3f-cfa3c704cb65@csgroup.eu> (raw)
In-Reply-To: <20220519021706.GA3526833@roeck-us.net>
Le 19/05/2022 à 04:17, Guenter Roeck a écrit :
> On Tue, Mar 22, 2022 at 04:40:20PM +0100, Christophe Leroy wrote:
>> Once init is done, initmem is freed forever so no need to
>> test system_state at every call to patch_instruction().
>>
>> Use jump_label.
>>
>> This reduces by 2% the time needed to activate ftrace on an 8xx.
>>
>
> It also causes the qemu mpc8544ds emulation to crash.
>
> BUG: Unable to handle kernel data access on write at 0xc122eb34
> Faulting instruction address: 0xc001b580
> Oops: Kernel access of bad area, sig: 11 [#1]
> BE PAGE_SIZE=4K MPC8544 DS
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper Not tainted 5.18.0-rc7-next-20220518 #1
> NIP: c001b580 LR: c001b560 CTR: 00000003
> REGS: c5107dd0 TRAP: 0300 Not tainted (5.18.0-rc7-next-20220518)
> MSR: 00009000 <EE,ME> CR: 24000882 XER: 00000000
> DEAR: c122eb34 ESR: 00800000
> GPR00: c001b560 c5107ec0 c5120020 10000000 00000000 00000078 0c000000 cfffffff
> GPR08: c001e9ec 00000001 00000007 00000000 44000882 00000000 c0005178 00000000
> GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> GPR24: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 c1230000
> NIP [c001b580] free_initmem+0x48/0xa8
> LR [c001b560] free_initmem+0x28/0xa8
> Call Trace:
> [c5107ec0] [c001b560] free_initmem+0x28/0xa8 (unreliable)
> [c5107ee0] [c00051b0] kernel_init+0x38/0x150
> [c5107f00] [c001626c] ret_from_kernel_thread+0x5c/0x64
> Instruction dump:
> 3fe0c123 912a00dc 90010024 48000665 3d20c218 8929fa65 2c090000 41820058
> 813feb34 2c090000 4082003c 39200001 <913feb34> 80010024 3cc0c114 83e1001c
>
> Reverting this patch fixes the problem.
>
That's strange.
I was able to reproduce the problem.
Removing the __ro_after_init in front of
DEFINE_STATIC_KEY_FALSE(init_mem_is_free) fixes the problem.
I can't understand why, mark_readonly() is called after free_initmem().
Christophe
next prev parent reply other threads:[~2022-05-19 6:28 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-22 15:40 [PATCH v1 0/4] Kill the time spent in patch_instruction() Christophe Leroy
2022-03-22 15:40 ` [PATCH v1 1/4] powerpc/code-patching: Don't call is_vmalloc_or_module_addr() without CONFIG_MODULES Christophe Leroy
2022-09-27 14:33 ` Christophe Leroy
2022-03-22 15:40 ` [PATCH v1 2/4] powerpc/code-patching: Speed up page mapping/unmapping Christophe Leroy
2022-09-27 14:33 ` Christophe Leroy
2022-03-22 15:40 ` [PATCH v1 3/4] powerpc/code-patching: Use jump_label for testing freed initmem Christophe Leroy
2022-05-19 2:17 ` Guenter Roeck
2022-05-19 6:27 ` Christophe Leroy [this message]
2022-05-19 6:53 ` Christophe Leroy
2022-05-19 17:27 ` Christophe Leroy
2022-09-27 14:33 ` Christophe Leroy
2022-03-22 15:40 ` [PATCH v1 4/4] powerpc/code-patching: Use jump_label to check if poking_init() is done Christophe Leroy
2022-09-27 14:33 ` Christophe Leroy
2022-05-15 10:28 ` [PATCH v1 0/4] Kill the time spent in patch_instruction() Michael Ellerman
2022-05-17 6:44 ` Christophe Leroy
2022-05-17 12:37 ` Michael Ellerman
2022-05-31 6:24 ` Christophe Leroy
2022-06-24 7:06 ` Christophe Leroy
2022-09-27 14:33 ` Christophe Leroy
2022-09-27 14:33 ` [PATCH v1 1/6] powerpc/code-patching: Use pte_offset_kernel() instead of virt_to_kpte() Christophe Leroy
2022-09-27 14:33 ` [PATCH v1 2/6] powerpc/code-patching: Remove #ifdef CONFIG_STRICT_KERNEL_RWX Christophe Leroy
2022-09-27 14:33 ` [PATCH v1 3/6] powerpc/feature-fixups: Refactor entry fixups patching Christophe Leroy
2022-09-27 14:33 ` [PATCH v1 4/6] powerpc/feature-fixups: Refactor other " Christophe Leroy
2022-09-27 14:33 ` [PATCH v1 5/6] powerpc/feature-fixups: Do not patch init section after init Christophe Leroy
2022-09-27 14:33 ` [PATCH v1 6/6] powerpc/code-patching: Remove protection against patching init addresses " Christophe Leroy
2022-09-27 14:38 ` [PATCH v1 0/4] Kill the time spent in patch_instruction() Christophe Leroy
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