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Date: Mon, 29 Jul 2019 13:08:08 +0200
From: Christophe Leroy <christophe.leroy@....fr>
To: Jason Yan <yanaijie@...wei.com>, mpe@...erman.id.au,
linuxppc-dev@...ts.ozlabs.org, diana.craciun@....com,
benh@...nel.crashing.org, paulus@...ba.org, npiggin@...il.com,
keescook@...omium.org, kernel-hardening@...ts.openwall.com
Cc: linux-kernel@...r.kernel.org, wangkefeng.wang@...wei.com,
yebin10@...wei.com, thunder.leizhen@...wei.com, jingxiangfeng@...wei.com,
fanchengyang@...wei.com
Subject: Re: [RFC PATCH 05/10] powerpc/fsl_booke/32: introduce
reloc_kernel_entry() helper
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@...wei.com>
> Cc: Diana Craciun <diana.craciun@....com>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: Christophe Leroy <christophe.leroy@....fr>
> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> Cc: Paul Mackerras <paulus@...ba.org>
> Cc: Nicholas Piggin <npiggin@...il.com>
> Cc: Kees Cook <keescook@...omium.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
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