riscv: Implement Shadow Call Stack

Implement CONFIG_SHADOW_CALL_STACK for RISC-V. When enabled, the compiler injects instructions to all non-leaf C functions to store the return address to the shadow stack and unconditionally load it again before returning, which makes it harder to corrupt the return address through a stack overflow, for example. The active shadow call stack pointer is stored in the gp register, which makes SCS incompatible with gp relaxation. Use --no-relax-gp to ensure gp relaxation is disabled and disable global pointer loading. Add SCS pointers to struct thread_info, implement SCS initialization, and task switching Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/r/20230927224757.1154247-12-samitolvanen@google.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2026-10-01 18:21:29 +00:00 · 2023-09-27 22:48:02 +00:00 · 2023-09-27 22:48:02 +00:00 · d1584d791a
commit d1584d791a
parent e609b4f425
10 changed files with 99 additions and 1 deletions
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
--- a/arch/riscv/include/asm/asm.h
+++ b/arch/riscv/include/asm/asm.h
--- a/arch/riscv/include/asm/scs.h
+++ b/arch/riscv/include/asm/scs.h
--- a/arch/riscv/include/asm/thread_info.h
+++ b/arch/riscv/include/asm/thread_info.h
--- a/arch/riscv/kernel/asm-offsets.c
+++ b/arch/riscv/kernel/asm-offsets.c
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
--- a/arch/riscv/kernel/vdso/Makefile
+++ b/arch/riscv/kernel/vdso/Makefile
--- a/arch/riscv/purgatory/Makefile
+++ b/arch/riscv/purgatory/Makefile