RISC-V: Check clint_time_val before use

2020-09-30T18:05:14+00:00

The NoMMU kernel is broken for QEMU virt machine from Linux-5.9-rc6 because clint_time_val is used even before CLINT driver is probed at following places: 1. rand_initialize() calls get_cycles() which in-turn uses clint_time_val 2. boot_init_stack_canary() calls get_cycles() which in-turn uses clint_time_val The issue#1 (above) is fixed by providing custom random_get_entropy() for RISC-V NoMMU kernel. For issue#2 (above), we remove dependency of boot_init_stack_canary() on get_cycles() and this is aligned with the boot_init_stack_canary() implementations of ARM, ARM64 and MIPS kernel. Fixes: d5be89a8d118 ("RISC-V: Resurrect the MMIO timer implementation for M-mode systems") Signed-off-by: Anup Patel Tested-by: Damien Le Moal Signed-off-by: Palmer Dabbelt

riscv: Add STACKPROTECTOR supported

2020-07-30T18:37:39+00:00

The -fstack-protector & -fstack-protector-strong features are from gcc. The patch only add basic kernel support to stack-protector feature and some arch could have its own solution such as ARM64_PTR_AUTH. After enabling STACKPROTECTOR and STACKPROTECTOR_STRONG, the .text size is expanded from 0x7de066 to 0x81fb32 (only 5%) to add canary checking code. Signed-off-by: Guo Ren Reviewed-by: Kees Cook Signed-off-by: Palmer Dabbelt

kernel/linux.git/arch/riscv/include/asm/stackprotector.h, branch linux-5.9.y

RISC-V: Check clint_time_val before use

riscv: Add STACKPROTECTOR supported