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From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Jason Yan <yanaijie@huawei.com>,
	mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org,
	diana.craciun@nxp.com, benh@kernel.crashing.org,
	paulus@samba.org, npiggin@gmail.com, keescook@chromium.org,
	kernel-hardening@lists.openwall.com
Cc: linux-kernel@vger.kernel.org, wangkefeng.wang@huawei.com,
	yebin10@huawei.com, thunder.leizhen@huawei.com,
	jingxiangfeng@huawei.com, fanchengyang@huawei.com
Subject: Re: [RFC PATCH 05/10] powerpc/fsl_booke/32: introduce reloc_kernel_entry() helper
Date: Mon, 29 Jul 2019 13:08:08 +0200
Message-ID: <e4ccd015-a9c4-b0a6-e3ca-d37a04e29ec6@c-s.fr> (raw)
In-Reply-To: <20190717080621.40424-6-yanaijie@huawei.com>



Le 17/07/2019 à 10:06, Jason Yan a écrit :
> Add a new helper reloc_kernel_entry() to jump back to the start of the
> new kernel. After we put the new kernel in a randomized place we can use
> this new helper to enter the kernel and begin to relocate again.
> 
> Signed-off-by: Jason Yan <yanaijie@huawei.com>
> Cc: Diana Craciun <diana.craciun@nxp.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Christophe Leroy <christophe.leroy@c-s.fr>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Nicholas Piggin <npiggin@gmail.com>
> Cc: Kees Cook <keescook@chromium.org>
> ---
>   arch/powerpc/kernel/head_fsl_booke.S | 16 ++++++++++++++++
>   arch/powerpc/mm/mmu_decl.h           |  1 +
>   2 files changed, 17 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
> index a57d44638031..ce40f96dae20 100644
> --- a/arch/powerpc/kernel/head_fsl_booke.S
> +++ b/arch/powerpc/kernel/head_fsl_booke.S
> @@ -1144,6 +1144,22 @@ _GLOBAL(create_tlb_entry)
>   	sync
>   	blr
>   
> +/*
> + * Return to the start of the relocated kernel and run again
> + * r3 - virtual address of fdt
> + * r4 - entry of the kernel
> + */
> +_GLOBAL(reloc_kernel_entry)
> +	mfmsr	r7
> +	li	r8,(MSR_IS | MSR_DS)
> +	andc	r7,r7,r8

Instead of the li/andc, what about the following:

rlwinm r7, r7, 0, ~(MSR_IS | MSR_DS)

> +
> +	mtspr	SPRN_SRR0,r4
> +	mtspr	SPRN_SRR1,r7
> +	isync
> +	sync
> +	rfi

Are the isync/sync really necessary ? AFAIK, rfi is context synchronising.

> +
>   /*
>    * Create a tlb entry with the same effective and physical address as
>    * the tlb entry used by the current running code. But set the TS to 1.
> diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
> index d7737cf97cee..dae8e9177574 100644
> --- a/arch/powerpc/mm/mmu_decl.h
> +++ b/arch/powerpc/mm/mmu_decl.h
> @@ -143,6 +143,7 @@ extern void adjust_total_lowmem(void);
>   extern int switch_to_as1(void);
>   extern void restore_to_as0(int esel, int offset, void *dt_ptr, int bootcpu);
>   extern void create_tlb_entry(phys_addr_t phys, unsigned long virt, int entry);
> +extern void reloc_kernel_entry(void *fdt, int addr);

No new 'extern' please, see 
https://openpower.xyz/job/snowpatch/job/snowpatch-linux-checkpatch/8125//artifact/linux/checkpatch.log


>   #endif
>   extern void loadcam_entry(unsigned int index);
>   extern void loadcam_multi(int first_idx, int num, int tmp_idx);
> 

Christophe

  reply index

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-17  8:06 [RFC PATCH 00/10] implement KASLR for powerpc/fsl_booke/32 Jason Yan
2019-07-17  8:06 ` [RFC PATCH 01/10] powerpc: unify definition of M_IF_NEEDED Jason Yan
2019-07-29 10:59   ` Christophe Leroy
2019-07-17  8:06 ` [RFC PATCH 02/10] powerpc: move memstart_addr and kernstart_addr to init-common.c Jason Yan
2019-07-29 11:00   ` Christophe Leroy
2019-07-29 14:31   ` Christoph Hellwig
2019-07-30  0:47     ` Jason Yan
2019-07-17  8:06 ` [RFC PATCH 03/10] powerpc: introduce kimage_vaddr to store the kernel base Jason Yan
2019-07-29 11:00   ` Christophe Leroy
2019-07-29 14:32   ` Christoph Hellwig
2019-07-17  8:06 ` [RFC PATCH 04/10] powerpc/fsl_booke/32: introduce create_tlb_entry() helper Jason Yan
2019-07-29 11:05   ` Christophe Leroy
2019-07-29 13:26     ` Jason Yan
2019-07-17  8:06 ` [RFC PATCH 05/10] powerpc/fsl_booke/32: introduce reloc_kernel_entry() helper Jason Yan
2019-07-29 11:08   ` Christophe Leroy [this message]
2019-07-29 13:35     ` Jason Yan
2019-07-17  8:06 ` [RFC PATCH 06/10] powerpc/fsl_booke/32: implement KASLR infrastructure Jason Yan
2019-07-29 11:16   ` Christophe Leroy
2019-07-17  8:06 ` [RFC PATCH 07/10] powerpc/fsl_booke/32: randomize the kernel image offset Jason Yan
2019-07-29 11:33   ` Christophe Leroy
2019-07-29 13:53     ` Jason Yan
2019-07-17  8:06 ` [RFC PATCH 08/10] powerpc/fsl_booke/kaslr: clear the original kernel if randomized Jason Yan
2019-07-29 11:19   ` Christophe Leroy
2019-07-29 13:43     ` Jason Yan
2019-07-17  8:06 ` [RFC PATCH 09/10] powerpc/fsl_booke/kaslr: support nokaslr cmdline parameter Jason Yan
2019-07-29 11:38   ` Christophe Leroy
2019-07-29 14:04     ` Jason Yan
2019-07-17  8:06 ` [RFC PATCH 10/10] powerpc/fsl_booke/kaslr: dump out kernel offset information on panic Jason Yan
2019-07-29 11:43   ` Christophe Leroy
2019-07-29 14:08     ` Jason Yan
2019-07-25  7:16 ` [RFC PATCH 00/10] implement KASLR for powerpc/fsl_booke/32 Jason Yan
2019-07-25 19:58   ` Kees Cook
2019-07-26  7:20     ` Jason Yan
2019-07-26 16:15       ` Kees Cook
2019-07-26  7:04   ` Diana Madalina Craciun
2019-07-26  7:26     ` Jason Yan
2019-07-29 14:30 ` Diana Madalina Craciun

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