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| author | Palmer Dabbelt <palmer@rivosinc.com> | 2023-11-02 14:05:23 -0700 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2023-11-02 14:05:23 -0700 |
| commit | 24005d184aaa80984e0511c4ec6e6a0860fdddb8 (patch) | |
| tree | 17a00f1378a195d6f4af679f2edecd003662ffd1 /arch/riscv/Kconfig | |
| parent | 4630d6daaba81560379d7ee5107100671c305992 (diff) | |
| parent | 245561ba6d5de42bf73d501f910b181bc7fa5601 (diff) | |
Merge patch series "riscv: SCS support"
Sami Tolvanen <samitolvanen@google.com> says:
This series adds Shadow Call Stack (SCS) support for RISC-V. SCS
uses compiler instrumentation to store return addresses in a
separate shadow stack to protect them against accidental or
malicious overwrites. More information about SCS can be found
here:
https://clang.llvm.org/docs/ShadowCallStack.html
Patch 1 is from Deepak, and it simplifies VMAP_STACK overflow
handling by adding support for accessing per-CPU variables
directly in assembly. The patch is included in this series to
make IRQ stack switching cleaner with SCS, and I've simply
rebased it and fixed a couple of minor issues. Patch 2 uses this
functionality to clean up the stack switching by moving duplicate
code into a single function. On RISC-V, the compiler uses the
gp register for storing the current shadow call stack pointer,
which is incompatible with global pointer relaxation. Patch 3
moves global pointer loading into a macro that can be easily
disabled with SCS. Patch 4 implements SCS register loading and
switching, and allows the feature to be enabled, and patch 5 adds
separate per-CPU IRQ shadow call stacks when CONFIG_IRQ_STACKS is
enabled. Patch 6 fixes the backward-edge CFI test in lkdtm for
RISC-V.
Note that this series requires Clang 17. Earlier Clang versions
support SCS on RISC-V, but use the x18 register instead of gp,
which isn't ideal. gcc has SCS support for arm64, but I'm not
aware of plans to support RISC-V. Once the Zicfiss extension is
ratified, it's probably preferable to use hardware-backed shadow
stacks instead of SCS on hardware that supports the extension,
and we may want to consider implementing CONFIG_DYNAMIC_SCS to
patch between the implementation at runtime (similarly to the
arm64 implementation, which switches to SCS when hardware PAC
support isn't available).
* b4-shazam-merge:
lkdtm: Fix CFI_BACKWARD on RISC-V
riscv: Use separate IRQ shadow call stacks
riscv: Implement Shadow Call Stack
riscv: Move global pointer loading to a macro
riscv: Deduplicate IRQ stack switching
riscv: VMAP_STACK overflow detection thread-safe
Link: https://lore.kernel.org/r/20230927224757.1154247-8-samitolvanen@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'arch/riscv/Kconfig')
| -rw-r--r-- | arch/riscv/Kconfig | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 805c8ab7f23b..ad96f9c1fc7f 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -49,6 +49,7 @@ config RISCV select ARCH_SUPPORTS_HUGETLBFS if MMU select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU select ARCH_SUPPORTS_PER_VMA_LOCK if MMU + select ARCH_SUPPORTS_SHADOW_CALL_STACK if HAVE_SHADOW_CALL_STACK select ARCH_USE_MEMTEST select ARCH_USE_QUEUED_RWLOCKS select ARCH_USES_CFI_TRAPS if CFI_CLANG @@ -175,6 +176,11 @@ config GCC_SUPPORTS_DYNAMIC_FTRACE def_bool CC_IS_GCC depends on $(cc-option,-fpatchable-function-entry=8) +config HAVE_SHADOW_CALL_STACK + def_bool $(cc-option,-fsanitize=shadow-call-stack) + # https://github.com/riscv-non-isa/riscv-elf-psabi-doc/commit/a484e843e6eeb51f0cb7b8819e50da6d2444d769 + depends on $(ld-option,--no-relax-gp) + config ARCH_MMAP_RND_BITS_MIN default 18 if 64BIT default 8 |