diff options
| author | Sami Tolvanen <samitolvanen@google.com> | 2023-07-10 18:35:46 +0000 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2023-08-23 14:16:36 -0700 |
| commit | 08d0ce30e0e4fcb5f06c90fe40387b1ce9324833 (patch) | |
| tree | 69f769ebd80061215865aa13bc4bc301ab4e446f /arch/riscv/include/asm/syscall.h | |
| parent | 06c2afb862f9da8dc5efa4b6076a0e48c3fbaaa5 (diff) | |
riscv: Implement syscall wrappers
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_<compat_>sys_<name> takes a pt_regs
pointer and extracts arguments from registers, __se_<compat_>sys_<name>
is a sign-extension wrapper that casts the long arguments to the
correct types for the real syscall implementation, which is named
__do_<compat_>sys_<name>.
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20230710183544.999540-9-samitolvanen@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'arch/riscv/include/asm/syscall.h')
| -rw-r--r-- | arch/riscv/include/asm/syscall.h | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h index 0148c6bd9675..121fff429dce 100644 --- a/arch/riscv/include/asm/syscall.h +++ b/arch/riscv/include/asm/syscall.h @@ -75,7 +75,7 @@ static inline int syscall_get_arch(struct task_struct *task) #endif } -typedef long (*syscall_t)(ulong, ulong, ulong, ulong, ulong, ulong, ulong); +typedef long (*syscall_t)(const struct pt_regs *); static inline void syscall_handler(struct pt_regs *regs, ulong syscall) { syscall_t fn; @@ -87,8 +87,7 @@ static inline void syscall_handler(struct pt_regs *regs, ulong syscall) #endif fn = sys_call_table[syscall]; - regs->a0 = fn(regs->orig_a0, regs->a1, regs->a2, - regs->a3, regs->a4, regs->a5, regs->a6); + regs->a0 = fn(regs); } static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs) |