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Date: Mon, 7 Nov 2022 19:06:39 +0530 From: Anshuman Khandual <anshuman.khandual@....com> To: Ard Biesheuvel <ardb@...nel.org> Cc: linux-arm-kernel@...ts.infradead.org, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, Mark Brown <broonie@...nel.org>, Mark Rutland <mark.rutland@....com>, linux-kernel@...r.kernel.org Subject: Re: [PATCH V2] arm64/mm: Simplify and document pte_to_phys() for 52 bit addresses On 11/7/22 17:32, Ard Biesheuvel wrote: > Hello Anshuman, > > On Mon, 7 Nov 2022 at 12:49, Anshuman Khandual > <anshuman.khandual@....com> wrote: >> >> pte_to_phys() assembly definition does multiple bits field transformations >> to derive physical address, embedded inside a page table entry. Unlike its >> C counter part i.e __pte_to_phys(), pte_to_phys() is not very apparent. It >> simplifies these operations via a new macro PTE_ADDR_HIGH_SHIFT indicating >> how far the pte encoded higher address bits need to be left shifted. While >> here, this also updates __pte_to_phys() and __phys_to_pte_val(). >> >> Cc: Catalin Marinas <catalin.marinas@....com> >> Cc: Will Deacon <will@...nel.org> >> Cc: Mark Brown <broonie@...nel.org> >> Cc: Mark Rutland <mark.rutland@....com> >> Cc: Ard Biesheuvel <ardb@...nel.org> >> Cc: linux-arm-kernel@...ts.infradead.org >> Cc: linux-kernel@...r.kernel.org >> Suggested-by: Ard Biesheuvel <ardb@...nel.org> >> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com> > > With the nit below fixed, this looks good to me > > Reviewed-by: Ard Biesheuvel <ardb@...nel.org> > >> --- >> This applies on v6.1-rc4 >> >> Changes in V2: >> >> - Added PTE_ADDR_HIGH_SHIFT based method per Ard >> >> Changes in V1: >> >> https://lore.kernel.org/all/20221031082421.1957288-1-anshuman.khandual@arm.com/ >> >> arch/arm64/include/asm/assembler.h | 8 +++----- >> arch/arm64/include/asm/pgtable-hwdef.h | 1 + >> arch/arm64/include/asm/pgtable.h | 4 ++-- >> 3 files changed, 6 insertions(+), 7 deletions(-) >> >> diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h >> index e5957a53be39..6a39a3601cf7 100644 >> --- a/arch/arm64/include/asm/assembler.h >> +++ b/arch/arm64/include/asm/assembler.h >> @@ -660,12 +660,10 @@ alternative_endif >> .endm >> >> .macro pte_to_phys, phys, pte >> -#ifdef CONFIG_ARM64_PA_BITS_52 >> - ubfiz \phys, \pte, #(48 - 16 - 12), #16 >> - bfxil \phys, \pte, #16, #32 >> - lsl \phys, \phys, #16 >> -#else >> and \phys, \pte, #PTE_ADDR_MASK >> +#ifdef CONFIG_ARM64_PA_BITS_52 >> + orr \phys, \phys, \phys, lsl #PTE_ADDR_HIGH_SHIFT >> + and \phys, \phys, GENMASK_ULL(PHYS_MASK_SHIFT - 1, PAGE_SHIFT) > > Please use tabs between the mnemonics and the arguments. Sure, will do that.
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