Messages in this thread Patch in this message | | | From | Alistair Francis <> | Subject | Re: [PATCH] RISC-V: Fix FIXMAP area corruption on RV32 systems | Date | Fri, 16 Aug 2019 17:57:29 +0000 |
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On Fri, 2019-08-16 at 11:49 +0000, Anup Patel wrote: > Currently, the order of various virtual memory areas in increasing > order of virtual addresses is as follows: > 1. User space area > 2. FIXMAP area > 3. VMALLOC area > 4. Kernel area > > The user space area starts at 0x0 and it's maximum size is > represented > by TASK_SIZE. > > On RV32 systems, TASK_SIZE is defined as VMALLOC_START which causes > the > user space area to overlap the FIXMAP area. This allows user space > apps > to potentially corrupt the FIXMAP area and kernel OF APIs will crash > whenever they access corrupted FDT in the FIXMAP area. > > On RV64 systems, TASK_SIZE is set to fixed 256GB and no other areas > happen to overlap so we don't see any FIXMAP area corruptions. > > This patch fixes FIXMAP area corruption on RV32 systems by setting > TASK_SIZE to FIXADDR_START. We also move FIXADDR_TOP, FIXADDR_SIZE, > and FIXADDR_START defines to asm/pgtable.h so that we can avoid > cyclic > header includes. > > Signed-off-by: Anup Patel <anup.patel@wdc.com>
This fixes the RV32 issue.
Tested-by: Alistair Francis <alistair.francis@wdc.com>
Alistair
> --- > arch/riscv/include/asm/fixmap.h | 4 ---- > arch/riscv/include/asm/pgtable.h | 12 ++++++++++-- > 2 files changed, 10 insertions(+), 6 deletions(-) > > diff --git a/arch/riscv/include/asm/fixmap.h > b/arch/riscv/include/asm/fixmap.h > index 9c66033c3a54..161f28d04a07 100644 > --- a/arch/riscv/include/asm/fixmap.h > +++ b/arch/riscv/include/asm/fixmap.h > @@ -30,10 +30,6 @@ enum fixed_addresses { > __end_of_fixed_addresses > }; > > -#define FIXADDR_SIZE (__end_of_fixed_addresses * PAGE_SIZE) > -#define FIXADDR_TOP (VMALLOC_START) > -#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) > - > #define FIXMAP_PAGE_IO PAGE_KERNEL > > #define __early_set_fixmap __set_fixmap > diff --git a/arch/riscv/include/asm/pgtable.h > b/arch/riscv/include/asm/pgtable.h > index a364aba23d55..9dd08a006a28 100644 > --- a/arch/riscv/include/asm/pgtable.h > +++ b/arch/riscv/include/asm/pgtable.h > @@ -420,14 +420,22 @@ static inline void pgtable_cache_init(void) > #define VMALLOC_END (PAGE_OFFSET - 1) > #define VMALLOC_START (PAGE_OFFSET - VMALLOC_SIZE) > > +#define FIXADDR_TOP (VMALLOC_START) > +#ifdef CONFIG_64BIT > +#define FIXADDR_SIZE PMD_SIZE > +#else > +#define FIXADDR_SIZE PGDIR_SIZE > +#endif > +#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) > + > /* > - * Task size is 0x4000000000 for RV64 or 0xb800000 for RV32. > + * Task size is 0x4000000000 for RV64 or 0x9fc00000 for RV32. > * Note that PGDIR_SIZE must evenly divide TASK_SIZE. > */ > #ifdef CONFIG_64BIT > #define TASK_SIZE (PGDIR_SIZE * PTRS_PER_PGD / 2) > #else > -#define TASK_SIZE VMALLOC_START > +#define TASK_SIZE FIXADDR_START > #endif > > #include <asm-generic/pgtable.h>
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