| Message ID | 20241010140351.309922-4-ayan.kumar.halder@amd.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Enable early bootup of AArch64 MPU systems | expand |
+ Frediano for suggestion about header protection define name > +++ b/xen/arch/arm/include/asm/mpu/layout.h > @@ -0,0 +1,33 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > + > +#ifndef __ARM_MPU_LAYOUT_H__ > +#define __ARM_MPU_LAYOUT_H__ I think we are moving away from this notation: https://patchwork.kernel.org/project/xen-devel/patch/20241004081713.749031-6-frediano.ziglio@cloud.com/ Shall this be ASM___ARM__MPU__LAYOUT_H ? @Frediano > + > +#define XEN_START_ADDRESS CONFIG_XEN_START_ADDRESS > + > +/* > + * All MPU platforms need to provide a XEN_START_ADDRESS for linker. This > + * address indicates where Xen image will be loaded and run from. This > + * address must be aligned to a PAGE_SIZE. > + */ > +#if (XEN_START_ADDRESS % PAGE_SIZE) != 0 > +#error "XEN_START_ADDRESS must be aligned to 4KB" > +#endif > + > +/* > + * For MPU, XEN's virtual start address is same as the physical address. > + * The reason being MPU treats VA == PA. IOW, it cannot map the physical > + * address to a different fixed virtual address. So, the virtual start > + * address is determined by the physical address at which Xen is loaded. > + */ > +#define XEN_VIRT_START _AT(paddr_t, XEN_START_ADDRESS) > + > +#endif /* __ARM_MPU_LAYOUT_H__ */ ^-- ASM___ARM__MPU__LAYOUT_H ? Apart from that, the rest looks ok to me: Reviewed-by: Luca Fancellu <luca.fancellu@arm.com>
Hi, On 14/10/2024 19:53, Luca Fancellu wrote: > + Frediano for suggestion about header protection define name > >> +++ b/xen/arch/arm/include/asm/mpu/layout.h >> @@ -0,0 +1,33 @@ >> +/* SPDX-License-Identifier: GPL-2.0-only */ >> + >> +#ifndef __ARM_MPU_LAYOUT_H__ >> +#define __ARM_MPU_LAYOUT_H__ > I think we are moving away from this notation: > https://patchwork.kernel.org/project/xen-devel/patch/20241004081713.749031-6-frediano.ziglio@cloud.com/ > Shall this be ASM___ARM__MPU__LAYOUT_H ? @Frediano I could see that the patch hasn't been Rb yet and as per https://patchwork.kernel.org/project/xen-devel/cover/20241004081713.749031-1-frediano.ziglio@cloud.com/ , the new coding style is still under discussion. May be the Arm maintainers (Stefano, Julien, Bertrand, Michal) can provide their opinion on this. - Ayan
On 15/10/2024 17:24, Ayan Kumar Halder wrote: > Hi, Hi Ayan & Luca, > On 14/10/2024 19:53, Luca Fancellu wrote: >> + Frediano for suggestion about header protection define name >> >>> +++ b/xen/arch/arm/include/asm/mpu/layout.h >>> @@ -0,0 +1,33 @@ >>> +/* SPDX-License-Identifier: GPL-2.0-only */ >>> + >>> +#ifndef __ARM_MPU_LAYOUT_H__ >>> +#define __ARM_MPU_LAYOUT_H__ >> I think we are moving away from this notation: >> https://patchwork.kernel.org/project/xen-devel/patch/20241004081713.749031-6-frediano.ziglio@cloud.com/ >> Shall this be ASM___ARM__MPU__LAYOUT_H ? @Frediano > > I could see that the patch hasn't been Rb yet and as per > https://patchwork.kernel.org/project/xen-devel/cover/20241004081713.749031-1-frediano.ziglio@cloud.com/ , the new coding style is still under discussion. > > May be the Arm maintainers (Stefano, Julien, Bertrand, Michal) can > provide their opinion on this. The current guideline is been debating within among the committers. For now, please ignore the guideline. Cheers,
Hi, On 10/10/2024 15:03, Ayan Kumar Halder wrote: > From: Wei Chen <wei.chen@arm.com> > > On Armv8-A, Xen has a fixed virtual start address (link address too) for all > Armv8-A platforms. In an MMU based system, Xen can map its loaded address to > this virtual start address. So, on Armv8-A platforms, the Xen start address does > not need to be configurable. But on Armv8-R platforms, there is no MMU to map > loaded address to a fixed virtual address and different platforms will have very > different address space layout. So Xen cannot use a fixed physical address on > MPU based system and need to have it configurable. > > So, we introduce a Kconfig option for users to set the start address. The start > address needs to be aligned to 4KB. We have a check for this alignment. > > MPU allows us to define regions which are 64 bits aligned. This restriction > comes from the bitfields of PRBAR, PRLAR (the lower 6 bits are 0 extended to > provide the base and limit address of a region). This means that the start > address of Xen needs to be at least 64 bits aligned (as it will correspond to > the start address of memory protection region). > > As for now Xen on MPU tries to use the same memory alignment restrictions as it > has been for MMU. Unlike MMU where the starting virtual address is 2MB, Xen on > MPU needs the start address to be 4KB (ie page size) aligned. > > In case if the user forgets to set the start address, then 0xffffffff is used > as default. This is to trigger the error (on alignment check) and thereby prompt > user to set the start address. > > Also updated config.h so that it includes mpu/layout.h when CONFIG_MPU is > defined. > > Signed-off-by: Wei Chen <wei.chen@arm.com> > Signed-off-by: Jiamei.Xie <jiamei.xie@arm.com> > Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com> > --- > Changes from :- > > v1 - 1. Fixed some of the coding style issues. > 2. Reworded the help message. > 3. Updated the commit message. > > v2 - Added clarification for the use of page and page size. > > xen/arch/arm/Kconfig | 10 ++++++++ > xen/arch/arm/include/asm/config.h | 4 +++- > xen/arch/arm/include/asm/mpu/layout.h | 33 +++++++++++++++++++++++++++ > xen/arch/arm/setup.c | 8 +++++++ > xen/arch/arm/xen.lds.S | 6 +++++ > 5 files changed, 60 insertions(+), 1 deletion(-) > create mode 100644 xen/arch/arm/include/asm/mpu/layout.h > > diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig > index ed92eb67cb..15b2e4a227 100644 > --- a/xen/arch/arm/Kconfig > +++ b/xen/arch/arm/Kconfig > @@ -23,6 +23,16 @@ config ARCH_DEFCONFIG > default "arch/arm/configs/arm32_defconfig" if ARM_32 > default "arch/arm/configs/arm64_defconfig" if ARM_64 > > +config XEN_START_ADDRESS > + hex "Xen start address: keep default to use platform defined address" > + default 0xFFFFFFFF > + depends on MPU > + help > + Used to set customized address at which which Xen will be linked on MPU > + systems. Must be aligned to 4KB. > + 0xFFFFFFFF is used as default value to indicate that user has not > + customized this address. > + > menu "Architecture Features" > > choice > diff --git a/xen/arch/arm/include/asm/config.h b/xen/arch/arm/include/asm/config.h > index a2e22b659d..0a51142efd 100644 > --- a/xen/arch/arm/include/asm/config.h > +++ b/xen/arch/arm/include/asm/config.h > @@ -69,8 +69,10 @@ > #include <xen/const.h> > #include <xen/page-size.h> > > -#ifdef CONFIG_MMU > +#if defined(CONFIG_MMU) > #include <asm/mmu/layout.h> > +#elif defined(CONFIG_MPU) > +#include <asm/mpu/layout.h> > #else > # error "Unknown memory management layout" > #endif > diff --git a/xen/arch/arm/include/asm/mpu/layout.h b/xen/arch/arm/include/asm/mpu/layout.h > new file mode 100644 > index 0000000000..d6d397f4c2 > --- /dev/null > +++ b/xen/arch/arm/include/asm/mpu/layout.h > @@ -0,0 +1,33 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > + > +#ifndef __ARM_MPU_LAYOUT_H__ > +#define __ARM_MPU_LAYOUT_H__ > + > +#define XEN_START_ADDRESS CONFIG_XEN_START_ADDRESS > + > +/* > + * All MPU platforms need to provide a XEN_START_ADDRESS for linker. This > + * address indicates where Xen image will be loaded and run from. This > + * address must be aligned to a PAGE_SIZE. > + */ > +#if (XEN_START_ADDRESS % PAGE_SIZE) != 0 > +#error "XEN_START_ADDRESS must be aligned to 4KB" > +#endif > + > +/* > + * For MPU, XEN's virtual start address is same as the physical address. > + * The reason being MPU treats VA == PA. IOW, it cannot map the physical > + * address to a different fixed virtual address. So, the virtual start > + * address is determined by the physical address at which Xen is loaded. > + */ > +#define XEN_VIRT_START _AT(paddr_t, XEN_START_ADDRESS) > + > +#endif /* __ARM_MPU_LAYOUT_H__ */ > +/* > + * Local variables: > + * mode: C > + * c-file-style: "BSD" > + * c-basic-offset: 4 > + * indent-tabs-mode: nil > + * End: > + */ > diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c > index 71ebaa77ca..0203771164 100644 > --- a/xen/arch/arm/setup.c > +++ b/xen/arch/arm/setup.c > @@ -295,6 +295,14 @@ void asmlinkage __init start_xen(unsigned long fdt_paddr) > struct domain *d; > int rc, i; > > +#ifdef CONFIG_MPU > + /* > + * Unlike MMU, MPU does not use pages for translation. However, we continue > + * to use PAGE_SIZE to denote 4KB. This is so that the existing memory > + * management based on pages, continue to work for now. > + */ > + BUILD_BUG_ON(PAGE_SIZE != SZ_4K); > +#endif I think it would be better suited in mm.c or mpu/*.c. > dcache_line_bytes = read_dcache_line_bytes(); > > percpu_init_areas(); > diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S > index bd884664ad..fe4b468cca 100644 > --- a/xen/arch/arm/xen.lds.S > +++ b/xen/arch/arm/xen.lds.S > @@ -231,6 +231,12 @@ SECTIONS > */ > ASSERT(_start == XEN_VIRT_START, "_start != XEN_VIRT_START") > > +/* > + * On MPU based platforms, the starting address is to be provided by user. > + * One need to check that it is 4KB aligned. > + */ > +ASSERT(IS_ALIGNED(_start, 4096), "starting address is misaligned") > + Shouldn't this be protected with #ifdef CONFIG_MPU? Also, it would probably be useful to start the exact size in the error message. > /* > * We require that Xen is loaded at a page boundary, so this ensures that any > * code running on the identity map cannot cross a section boundary. Cheers,
On 18/10/2024 22:59, Julien Grall wrote: > Hi, Hi Julien, Few clarifications. > > On 10/10/2024 15:03, Ayan Kumar Halder wrote: >> From: Wei Chen <wei.chen@arm.com> >> >> On Armv8-A, Xen has a fixed virtual start address (link address too) >> for all >> Armv8-A platforms. In an MMU based system, Xen can map its loaded >> address to >> this virtual start address. So, on Armv8-A platforms, the Xen start >> address does >> not need to be configurable. But on Armv8-R platforms, there is no >> MMU to map >> loaded address to a fixed virtual address and different platforms >> will have very >> different address space layout. So Xen cannot use a fixed physical >> address on >> MPU based system and need to have it configurable. >> >> So, we introduce a Kconfig option for users to set the start address. >> The start >> address needs to be aligned to 4KB. We have a check for this alignment. >> >> MPU allows us to define regions which are 64 bits aligned. This >> restriction >> comes from the bitfields of PRBAR, PRLAR (the lower 6 bits are 0 >> extended to >> provide the base and limit address of a region). This means that the >> start >> address of Xen needs to be at least 64 bits aligned (as it will >> correspond to >> the start address of memory protection region). >> >> As for now Xen on MPU tries to use the same memory alignment >> restrictions as it >> has been for MMU. Unlike MMU where the starting virtual address is >> 2MB, Xen on >> MPU needs the start address to be 4KB (ie page size) aligned. >> >> In case if the user forgets to set the start address, then 0xffffffff >> is used >> as default. This is to trigger the error (on alignment check) and >> thereby prompt >> user to set the start address. >> >> Also updated config.h so that it includes mpu/layout.h when >> CONFIG_MPU is >> defined. >> >> Signed-off-by: Wei Chen <wei.chen@arm.com> >> Signed-off-by: Jiamei.Xie <jiamei.xie@arm.com> >> Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com> >> --- >> Changes from :- >> >> v1 - 1. Fixed some of the coding style issues. >> 2. Reworded the help message. >> 3. Updated the commit message. >> >> v2 - Added clarification for the use of page and page size. >> >> xen/arch/arm/Kconfig | 10 ++++++++ >> xen/arch/arm/include/asm/config.h | 4 +++- >> xen/arch/arm/include/asm/mpu/layout.h | 33 +++++++++++++++++++++++++++ >> xen/arch/arm/setup.c | 8 +++++++ >> xen/arch/arm/xen.lds.S | 6 +++++ >> 5 files changed, 60 insertions(+), 1 deletion(-) >> create mode 100644 xen/arch/arm/include/asm/mpu/layout.h >> >> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig >> index ed92eb67cb..15b2e4a227 100644 >> --- a/xen/arch/arm/Kconfig >> +++ b/xen/arch/arm/Kconfig >> @@ -23,6 +23,16 @@ config ARCH_DEFCONFIG >> default "arch/arm/configs/arm32_defconfig" if ARM_32 >> default "arch/arm/configs/arm64_defconfig" if ARM_64 >> +config XEN_START_ADDRESS >> + hex "Xen start address: keep default to use platform defined >> address" >> + default 0xFFFFFFFF >> + depends on MPU >> + help >> + Used to set customized address at which which Xen will be >> linked on MPU >> + systems. Must be aligned to 4KB. >> + 0xFFFFFFFF is used as default value to indicate that user has not >> + customized this address. >> + >> menu "Architecture Features" >> choice >> diff --git a/xen/arch/arm/include/asm/config.h >> b/xen/arch/arm/include/asm/config.h >> index a2e22b659d..0a51142efd 100644 >> --- a/xen/arch/arm/include/asm/config.h >> +++ b/xen/arch/arm/include/asm/config.h >> @@ -69,8 +69,10 @@ >> #include <xen/const.h> >> #include <xen/page-size.h> >> -#ifdef CONFIG_MMU >> +#if defined(CONFIG_MMU) >> #include <asm/mmu/layout.h> >> +#elif defined(CONFIG_MPU) >> +#include <asm/mpu/layout.h> >> #else >> # error "Unknown memory management layout" >> #endif >> diff --git a/xen/arch/arm/include/asm/mpu/layout.h >> b/xen/arch/arm/include/asm/mpu/layout.h >> new file mode 100644 >> index 0000000000..d6d397f4c2 >> --- /dev/null >> +++ b/xen/arch/arm/include/asm/mpu/layout.h >> @@ -0,0 +1,33 @@ >> +/* SPDX-License-Identifier: GPL-2.0-only */ >> + >> +#ifndef __ARM_MPU_LAYOUT_H__ >> +#define __ARM_MPU_LAYOUT_H__ >> + >> +#define XEN_START_ADDRESS CONFIG_XEN_START_ADDRESS >> + >> +/* >> + * All MPU platforms need to provide a XEN_START_ADDRESS for linker. >> This >> + * address indicates where Xen image will be loaded and run from. This >> + * address must be aligned to a PAGE_SIZE. >> + */ >> +#if (XEN_START_ADDRESS % PAGE_SIZE) != 0 >> +#error "XEN_START_ADDRESS must be aligned to 4KB" >> +#endif >> + >> +/* >> + * For MPU, XEN's virtual start address is same as the physical >> address. >> + * The reason being MPU treats VA == PA. IOW, it cannot map the >> physical >> + * address to a different fixed virtual address. So, the virtual start >> + * address is determined by the physical address at which Xen is >> loaded. >> + */ >> +#define XEN_VIRT_START _AT(paddr_t, XEN_START_ADDRESS) >> + >> +#endif /* __ARM_MPU_LAYOUT_H__ */ >> +/* >> + * Local variables: >> + * mode: C >> + * c-file-style: "BSD" >> + * c-basic-offset: 4 >> + * indent-tabs-mode: nil >> + * End: >> + */ >> diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c >> index 71ebaa77ca..0203771164 100644 >> --- a/xen/arch/arm/setup.c >> +++ b/xen/arch/arm/setup.c >> @@ -295,6 +295,14 @@ void asmlinkage __init start_xen(unsigned long >> fdt_paddr) >> struct domain *d; >> int rc, i; >> +#ifdef CONFIG_MPU >> + /* >> + * Unlike MMU, MPU does not use pages for translation. However, >> we continue >> + * to use PAGE_SIZE to denote 4KB. This is so that the existing >> memory >> + * management based on pages, continue to work for now. >> + */ >> + BUILD_BUG_ON(PAGE_SIZE != SZ_4K); >> +#endif > > I think it would be better suited in mm.c or mpu/*.c. We do not have mpu/*.c at the moment. Also, I am not sure within which function in mm.c, should this change be incorporated. Can we take out this change from the current patch and put it in a later series when we support the lateboot of Xen (ie start_xen() onwards) for MPU ? > >> dcache_line_bytes = read_dcache_line_bytes(); >> percpu_init_areas(); >> diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S >> index bd884664ad..fe4b468cca 100644 >> --- a/xen/arch/arm/xen.lds.S >> +++ b/xen/arch/arm/xen.lds.S >> @@ -231,6 +231,12 @@ SECTIONS >> */ >> ASSERT(_start == XEN_VIRT_START, "_start != XEN_VIRT_START") >> +/* >> + * On MPU based platforms, the starting address is to be provided by >> user. >> + * One need to check that it is 4KB aligned. >> + */ >> +ASSERT(IS_ALIGNED(_start, 4096), "starting address is >> misaligned") >> + > > Shouldn't this be protected with #ifdef CONFIG_MPU? yes > Also, it would probably be useful to start the exact size in the error > message. Do you mean ? ASSERT(IS_ALIGNED(_start, 4096), "starting address should be aligned to 4KB") - Ayan
On 21/10/2024 13:40, Ayan Kumar Halder wrote: > > On 18/10/2024 22:59, Julien Grall wrote: >>> diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c >>> index 71ebaa77ca..0203771164 100644 >>> --- a/xen/arch/arm/setup.c >>> +++ b/xen/arch/arm/setup.c >>> @@ -295,6 +295,14 @@ void asmlinkage __init start_xen(unsigned long >>> fdt_paddr) >>> struct domain *d; >>> int rc, i; >>> +#ifdef CONFIG_MPU >>> + /* >>> + * Unlike MMU, MPU does not use pages for translation. However, >>> we continue >>> + * to use PAGE_SIZE to denote 4KB. This is so that the existing >>> memory >>> + * management based on pages, continue to work for now. >>> + */ >>> + BUILD_BUG_ON(PAGE_SIZE != SZ_4K); >>> +#endif >> >> I think it would be better suited in mm.c or mpu/*.c. > > We do not have mpu/*.c at the moment. But we are going to get some and most likely a mpu/mm.c, right? If so, I don't see why we can't create one right now. Anyway... > Also, I am not sure within which > function in mm.c, should this change be incorporated. in arm/mm.c, I could create a new function: static void __init __maybe_unused build_assertions(void) > > Can we take out this change from the current patch and put it in a later > series when we support the lateboot of Xen (ie start_xen() onwards) for > MPU ? I would say no. The BUILD_BUG_ON() is suited here. > >> >>> dcache_line_bytes = read_dcache_line_bytes(); >>> percpu_init_areas(); >>> diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S >>> index bd884664ad..fe4b468cca 100644 >>> --- a/xen/arch/arm/xen.lds.S >>> +++ b/xen/arch/arm/xen.lds.S >>> @@ -231,6 +231,12 @@ SECTIONS >>> */ >>> ASSERT(_start == XEN_VIRT_START, "_start != XEN_VIRT_START") >>> +/* >>> + * On MPU based platforms, the starting address is to be provided by >>> user. >>> + * One need to check that it is 4KB aligned. >>> + */ >>> +ASSERT(IS_ALIGNED(_start, 4096), "starting address is >>> misaligned") >>> + >> >> Shouldn't this be protected with #ifdef CONFIG_MPU? > yes >> Also, it would probably be useful to start the exact size in the error >> message. > > Do you mean ? > > ASSERT(IS_ALIGNED(_start, 4096), "starting address should be > aligned to 4KB") Yes. Cheers,
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig index ed92eb67cb..15b2e4a227 100644 --- a/xen/arch/arm/Kconfig +++ b/xen/arch/arm/Kconfig @@ -23,6 +23,16 @@ config ARCH_DEFCONFIG default "arch/arm/configs/arm32_defconfig" if ARM_32 default "arch/arm/configs/arm64_defconfig" if ARM_64 +config XEN_START_ADDRESS + hex "Xen start address: keep default to use platform defined address" + default 0xFFFFFFFF + depends on MPU + help + Used to set customized address at which which Xen will be linked on MPU + systems. Must be aligned to 4KB. + 0xFFFFFFFF is used as default value to indicate that user has not + customized this address. + menu "Architecture Features" choice diff --git a/xen/arch/arm/include/asm/config.h b/xen/arch/arm/include/asm/config.h index a2e22b659d..0a51142efd 100644 --- a/xen/arch/arm/include/asm/config.h +++ b/xen/arch/arm/include/asm/config.h @@ -69,8 +69,10 @@ #include <xen/const.h> #include <xen/page-size.h> -#ifdef CONFIG_MMU +#if defined(CONFIG_MMU) #include <asm/mmu/layout.h> +#elif defined(CONFIG_MPU) +#include <asm/mpu/layout.h> #else # error "Unknown memory management layout" #endif diff --git a/xen/arch/arm/include/asm/mpu/layout.h b/xen/arch/arm/include/asm/mpu/layout.h new file mode 100644 index 0000000000..d6d397f4c2 --- /dev/null +++ b/xen/arch/arm/include/asm/mpu/layout.h @@ -0,0 +1,33 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +#ifndef __ARM_MPU_LAYOUT_H__ +#define __ARM_MPU_LAYOUT_H__ + +#define XEN_START_ADDRESS CONFIG_XEN_START_ADDRESS + +/* + * All MPU platforms need to provide a XEN_START_ADDRESS for linker. This + * address indicates where Xen image will be loaded and run from. This + * address must be aligned to a PAGE_SIZE. + */ +#if (XEN_START_ADDRESS % PAGE_SIZE) != 0 +#error "XEN_START_ADDRESS must be aligned to 4KB" +#endif + +/* + * For MPU, XEN's virtual start address is same as the physical address. + * The reason being MPU treats VA == PA. IOW, it cannot map the physical + * address to a different fixed virtual address. So, the virtual start + * address is determined by the physical address at which Xen is loaded. + */ +#define XEN_VIRT_START _AT(paddr_t, XEN_START_ADDRESS) + +#endif /* __ARM_MPU_LAYOUT_H__ */ +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c index 71ebaa77ca..0203771164 100644 --- a/xen/arch/arm/setup.c +++ b/xen/arch/arm/setup.c @@ -295,6 +295,14 @@ void asmlinkage __init start_xen(unsigned long fdt_paddr) struct domain *d; int rc, i; +#ifdef CONFIG_MPU + /* + * Unlike MMU, MPU does not use pages for translation. However, we continue + * to use PAGE_SIZE to denote 4KB. This is so that the existing memory + * management based on pages, continue to work for now. + */ + BUILD_BUG_ON(PAGE_SIZE != SZ_4K); +#endif dcache_line_bytes = read_dcache_line_bytes(); percpu_init_areas(); diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S index bd884664ad..fe4b468cca 100644 --- a/xen/arch/arm/xen.lds.S +++ b/xen/arch/arm/xen.lds.S @@ -231,6 +231,12 @@ SECTIONS */ ASSERT(_start == XEN_VIRT_START, "_start != XEN_VIRT_START") +/* + * On MPU based platforms, the starting address is to be provided by user. + * One need to check that it is 4KB aligned. + */ +ASSERT(IS_ALIGNED(_start, 4096), "starting address is misaligned") + /* * We require that Xen is loaded at a page boundary, so this ensures that any * code running on the identity map cannot cross a section boundary.