riscv: Implement syscall wrappers

2023-08-23T21:16:36Z

Commit f0bddf50586d ("riscv: entry: Convert to generic entry") moved syscall handling to C code, which exposed function pointer type mismatches that trip fine-grained forward-edge Control-Flow Integrity (CFI) checks as syscall handlers are all called through the same syscall_t pointer type. To fix the type mismatches, implement pt_regs based syscall wrappers similarly to x86 and arm64. This patch is based on arm64 syscall wrappers added in commit 4378a7d4be30 ("arm64: implement syscall wrappers"), where the main goal was to minimize the risk of userspace-controlled values being used under speculation. This may be a concern for riscv in future as well. Following other architectures, the syscall wrappers generate three functions for each syscall; __riscv_sys_ takes a pt_regs pointer and extracts arguments from registers, __se_sys_ is a sign-extension wrapper that casts the long arguments to the correct types for the real syscall implementation, which is named __do_sys_. Reviewed-by: Kees Cook Tested-by: Nathan Chancellor Signed-off-by: Sami Tolvanen Link: https://lore.kernel.org/r/20230710183544.999540-9-samitolvanen@google.com Signed-off-by: Palmer Dabbelt

riscv: compat: syscall: Add compat_sys_call_table implementation

2022-04-26T20:36:25Z

Implement compat sys_call_table and some system call functions: truncate64, ftruncate64, fallocate, pread64, pwrite64, sync_file_range, readahead, fadvise64_64 which need argument translation. Signed-off-by: Guo Ren Signed-off-by: Guo Ren Reviewed-by: Arnd Bergmann Tested-by: Heiko Stuebner Link: https://lore.kernel.org/r/20220405071314.3225832-12-guoren@kernel.org Signed-off-by: Palmer Dabbelt

kernel.git/arch/riscv/kernel/compat_syscall_table.c, branch linux-6.10.y

riscv: Implement syscall wrappers

riscv: compat: syscall: Add compat_sys_call_table implementation