| Message ID | 20201028132456.5004-1-ardb@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: use correct section size macro to describe the FDT virtual address | expand |
On Wed, Oct 28, 2020 at 2:25 PM Ard Biesheuvel <ardb@kernel.org> wrote: > 149a3ffe62b9dbc3 ("9012/1: move device tree mapping out of linear region") > > created a permanent, read-only section mapping of the device tree blob > provided by the firmware, and added a set of macros to get the base and > size of the virtually mapped FDT based on the physical address. However, > while the mapping code uses the SECTION_SIZE macro correctly, the macros > use PMD_SIZE instead, which means something entirely different on ARM when > using short descriptors, and is therefore not the right quantity to use > here. So replace PMD_SIZE with SECTION_SIZE. While at it, change the names > of the macro and its parameter to clarify that it returns the virtual > address of the start of the FDT in memory, based on the physical address > in memory. > > Tested-by: Joel Stanley <joel@jms.id.au> > Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> > Signed-off-by: Ard Biesheuvel <ardb@kernel.org> 2 * SECTION_SIZE will be 2 MB on classic MMU and 4MB on LPAE right? Note in Documentation/arm/memory.rst: > -ffc00000 ffefffff Fixmap mapping region. Addresses provided > +ffc80000 ffefffff Fixmap mapping region. Addresses provided > by fix_to_virt() will be located here. > > +ffc00000 ffc7ffff Guard region > + > +ff800000 ffbfffff Permanent, fixed read-only mapping of the > + firmware provided DT blob So on the classic MMU the DTB mapping will use 0xff800000-0xff9fffff and on LPAE it will use the whole 0xff800000-0xffbfffff as in the doc? Just verifying that I understand this right... If I have understood what I just reviewed right: Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Yours, Linus Walleij
On Wed, 28 Oct 2020 at 16:20, Linus Walleij <linus.walleij@linaro.org> wrote: > > On Wed, Oct 28, 2020 at 2:25 PM Ard Biesheuvel <ardb@kernel.org> wrote: > > > 149a3ffe62b9dbc3 ("9012/1: move device tree mapping out of linear region") > > > > created a permanent, read-only section mapping of the device tree blob > > provided by the firmware, and added a set of macros to get the base and > > size of the virtually mapped FDT based on the physical address. However, > > while the mapping code uses the SECTION_SIZE macro correctly, the macros > > use PMD_SIZE instead, which means something entirely different on ARM when > > using short descriptors, and is therefore not the right quantity to use > > here. So replace PMD_SIZE with SECTION_SIZE. While at it, change the names > > of the macro and its parameter to clarify that it returns the virtual > > address of the start of the FDT in memory, based on the physical address > > in memory. > > > > Tested-by: Joel Stanley <joel@jms.id.au> > > Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> > > Signed-off-by: Ard Biesheuvel <ardb@kernel.org> > > 2 * SECTION_SIZE will be 2 MB on classic MMU and 4MB on > LPAE right? > Yes > Note in Documentation/arm/memory.rst: > > > -ffc00000 ffefffff Fixmap mapping region. Addresses provided > > +ffc80000 ffefffff Fixmap mapping region. Addresses provided > > by fix_to_virt() will be located here. > > > > +ffc00000 ffc7ffff Guard region > > + > > +ff800000 ffbfffff Permanent, fixed read-only mapping of the > > + firmware provided DT blob > > So on the classic MMU the DTB mapping will use 0xff800000-0xff9fffff > and on LPAE it will use the whole 0xff800000-0xffbfffff as in the doc? > Indeed > Just verifying that I understand this right... > > If I have understood what I just reviewed right: > Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > > Yours, > Linus Walleij
diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h index bb79e52aeb90..f717d7122d9d 100644 --- a/arch/arm/include/asm/memory.h +++ b/arch/arm/include/asm/memory.h @@ -68,8 +68,8 @@ #define XIP_VIRT_ADDR(physaddr) (MODULES_VADDR + ((physaddr) & 0x000fffff)) #define FDT_FIXED_BASE UL(0xff800000) -#define FDT_FIXED_SIZE (2 * PMD_SIZE) -#define FDT_VIRT_ADDR(physaddr) ((void *)(FDT_FIXED_BASE | (physaddr) % PMD_SIZE)) +#define FDT_FIXED_SIZE (2 * SECTION_SIZE) +#define FDT_VIRT_BASE(physbase) ((void *)(FDT_FIXED_BASE | (physbase) % SECTION_SIZE)) #if !defined(CONFIG_SMP) && !defined(CONFIG_ARM_LPAE) /* @@ -111,7 +111,7 @@ extern unsigned long vectors_base; #define MODULES_VADDR PAGE_OFFSET #define XIP_VIRT_ADDR(physaddr) (physaddr) -#define FDT_VIRT_ADDR(physaddr) ((void *)(physaddr)) +#define FDT_VIRT_BASE(physbase) ((void *)(physbase)) #endif /* !CONFIG_MMU */ diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c index 694aa6b4bd03..f90479d8b50c 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -1086,7 +1086,7 @@ void __init setup_arch(char **cmdline_p) void *atags_vaddr = NULL; if (__atags_pointer) - atags_vaddr = FDT_VIRT_ADDR(__atags_pointer); + atags_vaddr = FDT_VIRT_BASE(__atags_pointer); setup_processor(); if (atags_vaddr) {
Commit 149a3ffe62b9dbc3 ("9012/1: move device tree mapping out of linear region") created a permanent, read-only section mapping of the device tree blob provided by the firmware, and added a set of macros to get the base and size of the virtually mapped FDT based on the physical address. However, while the mapping code uses the SECTION_SIZE macro correctly, the macros use PMD_SIZE instead, which means something entirely different on ARM when using short descriptors, and is therefore not the right quantity to use here. So replace PMD_SIZE with SECTION_SIZE. While at it, change the names of the macro and its parameter to clarify that it returns the virtual address of the start of the FDT in memory, based on the physical address in memory. Tested-by: Joel Stanley <joel@jms.id.au> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- Already submitted as 9020/1. Related discussion can be found at https://lore.kernel.org/linux-arm-kernel/20201007083944.27910-3-ardb@kernel.org/ arch/arm/include/asm/memory.h | 6 +++--- arch/arm/kernel/setup.c | 2 +- 2 files changed, 4 insertions(+), 4 deletions(-)