| Message ID | 20190528161026.13193-5-steve.capper@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | 52-bit kernel + user VAs | expand |
On Tue, 28 May 2019 at 18:10, Steve Capper <steve.capper@arm.com> wrote: > > In order to prepare for a variable VA_BITS we need to account for a > variable size VMEMMAP which in turn means the position of the fixed map > is variable at compile time. > > Thus, we need to replace the BUILD_BUG_ON's that check the fixed map > position with BUG_ON's. > > Signed-off-by: Steve Capper <steve.capper@arm.com> Do we still need this patch now that VMEMMAP_SIZE is a compile time constant again? Or am I missing something? > --- > arch/arm64/mm/mmu.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index b0401b2ec4da..1b88d9d81954 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -846,7 +846,7 @@ void __init early_fixmap_init(void) > * The boot-ioremap range spans multiple pmds, for which > * we are not prepared: > */ > - BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT) > + BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT) > != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT)); > > if ((pmdp != fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN))) > @@ -914,9 +914,9 @@ void *__init __fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot) > * On 4k pages, we'll use section mappings for the FDT so we only > * have to be in the same PUD. > */ > - BUILD_BUG_ON(dt_virt_base % SZ_2M); > + BUG_ON(dt_virt_base % SZ_2M); > > - BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> SWAPPER_TABLE_SHIFT != > + BUG_ON(__fix_to_virt(FIX_FDT_END) >> SWAPPER_TABLE_SHIFT != > __fix_to_virt(FIX_BTMAP_BEGIN) >> SWAPPER_TABLE_SHIFT); > > offset = dt_phys % SWAPPER_BLOCK_SIZE; > -- > 2.20.1 >
On Tue, 28 May 2019 at 19:07, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > > On Tue, 28 May 2019 at 18:10, Steve Capper <steve.capper@arm.com> wrote: > > > > In order to prepare for a variable VA_BITS we need to account for a > > variable size VMEMMAP which in turn means the position of the fixed map > > is variable at compile time. > > > > Thus, we need to replace the BUILD_BUG_ON's that check the fixed map > > position with BUG_ON's. > > > > Signed-off-by: Steve Capper <steve.capper@arm.com> > > Do we still need this patch now that VMEMMAP_SIZE is a compile time > constant again? Or am I missing something? > Never mind. You are moving the start of the linear region and the start of the vmemmap region. I wonder if this is really necessry, though. On a 48-bit VA only system, the linear region could still start at 0xfff0_.... as long as we don't put any physical memory there (and we already move around our physical memory inside the linear region when KASLR is enabled) > > --- > > arch/arm64/mm/mmu.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > > index b0401b2ec4da..1b88d9d81954 100644 > > --- a/arch/arm64/mm/mmu.c > > +++ b/arch/arm64/mm/mmu.c > > @@ -846,7 +846,7 @@ void __init early_fixmap_init(void) > > * The boot-ioremap range spans multiple pmds, for which > > * we are not prepared: > > */ > > - BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT) > > + BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT) > > != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT)); > > > > if ((pmdp != fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN))) > > @@ -914,9 +914,9 @@ void *__init __fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot) > > * On 4k pages, we'll use section mappings for the FDT so we only > > * have to be in the same PUD. > > */ > > - BUILD_BUG_ON(dt_virt_base % SZ_2M); > > + BUG_ON(dt_virt_base % SZ_2M); > > > > - BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> SWAPPER_TABLE_SHIFT != > > + BUG_ON(__fix_to_virt(FIX_FDT_END) >> SWAPPER_TABLE_SHIFT != > > __fix_to_virt(FIX_BTMAP_BEGIN) >> SWAPPER_TABLE_SHIFT); > > > > offset = dt_phys % SWAPPER_BLOCK_SIZE; > > -- > > 2.20.1 > >
On Tue, May 28, 2019 at 07:11:22PM +0200, Ard Biesheuvel wrote: > On Tue, 28 May 2019 at 19:07, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > > > > On Tue, 28 May 2019 at 18:10, Steve Capper <steve.capper@arm.com> wrote: > > > > > > In order to prepare for a variable VA_BITS we need to account for a > > > variable size VMEMMAP which in turn means the position of the fixed map > > > is variable at compile time. > > > > > > Thus, we need to replace the BUILD_BUG_ON's that check the fixed map > > > position with BUG_ON's. > > > > > > Signed-off-by: Steve Capper <steve.capper@arm.com> > > > > Do we still need this patch now that VMEMMAP_SIZE is a compile time > > constant again? Or am I missing something? > > > > Never mind. You are moving the start of the linear region and the > start of the vmemmap region. > > I wonder if this is really necessry, though. On a 48-bit VA only > system, the linear region could still start at 0xfff0_.... as long as > we don't put any physical memory there (and we already move around our > physical memory inside the linear region when KASLR is enabled) > > Thanks Ard, This patch is actually superfluous, it was needed in earlier versions of the series; but VMEMMAP is fixed at compile time. I have removed this patch from the series. I will also see if I can simplify the de-constifying patches and bitmask replacement logic. Cheers,
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index b0401b2ec4da..1b88d9d81954 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -846,7 +846,7 @@ void __init early_fixmap_init(void) * The boot-ioremap range spans multiple pmds, for which * we are not prepared: */ - BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT) + BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT) != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT)); if ((pmdp != fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN))) @@ -914,9 +914,9 @@ void *__init __fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot) * On 4k pages, we'll use section mappings for the FDT so we only * have to be in the same PUD. */ - BUILD_BUG_ON(dt_virt_base % SZ_2M); + BUG_ON(dt_virt_base % SZ_2M); - BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> SWAPPER_TABLE_SHIFT != + BUG_ON(__fix_to_virt(FIX_FDT_END) >> SWAPPER_TABLE_SHIFT != __fix_to_virt(FIX_BTMAP_BEGIN) >> SWAPPER_TABLE_SHIFT); offset = dt_phys % SWAPPER_BLOCK_SIZE;
In order to prepare for a variable VA_BITS we need to account for a variable size VMEMMAP which in turn means the position of the fixed map is variable at compile time. Thus, we need to replace the BUILD_BUG_ON's that check the fixed map position with BUG_ON's. Signed-off-by: Steve Capper <steve.capper@arm.com> --- arch/arm64/mm/mmu.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)