linux/arch/riscv
Anup Patel a256f2e329 RISC-V: Fix FIXMAP area corruption on RV32 systems
Currently, various virtual memory areas of Linux RISC-V are organized
in increasing order of their virtual addresses is as follows:
1. User space area (This is lowest area and starts at 0x0)
2. FIXMAP area
3. VMALLOC area
4. Kernel area (This is highest area and starts at PAGE_OFFSET)

The maximum size of user space aread 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>
Tested-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
2019-08-28 15:30:12 -07:00
..
boot riscv: dts: fu540-c000: drop "timebase-frequency" 2019-07-31 12:26:10 -07:00
configs riscv: defconfig: Update the defconfig 2019-08-13 19:26:42 -07:00
include RISC-V: Fix FIXMAP area corruption on RV32 systems 2019-08-28 15:30:12 -07:00
kernel riscv: Correct the initialized flow of FP register 2019-08-14 13:11:11 -07:00
lib RISC-V: Remove udivdi3 2019-08-08 16:05:38 -07:00
mm RISC-V updates for v5.3 2019-07-18 12:26:59 -07:00
net bpf, riscv: Enable zext optimization for more RV64G ALU ops 2019-07-05 23:55:41 +02:00
Kconfig RISC-V updates for v5.3 2019-07-18 12:26:59 -07:00
Kconfig.debug RISC-V: Remove EARLY_PRINTK support 2018-12-17 10:23:46 -08:00
Kconfig.socs riscv: select SiFive platform drivers with SOC_SIFIVE 2019-07-01 13:20:01 -07:00
Makefile riscv: drop unneeded -Wall addition 2019-07-17 10:25:10 +09:00