From 37f57bd3faeac92e898c3381355f4fd2b6a80901 Mon Sep 17 00:00:00 2001 From: Jim Shu Date: Sun, 25 Jan 2026 21:09:56 -0700 Subject: [PATCH] arch/riscv: compile vdso with landing pad and shadow stack note User mode tasks compiled with Zicfilp may call indirectly into the vdso (like hwprobe indirect calls). Add support for compiling landing pads into the vdso. Landing pad instructions in the vdso will be no-ops for tasks which have not enabled landing pads. Furthermore, add support for the C sources of the vdso to be compiled with shadow stack and landing pads enabled as well. Landing pad and shadow stack instructions are emitted only when the VDSO_CFI cflags option is defined during compile. Signed-off-by: Jim Shu Reviewed-by: Zong Li Signed-off-by: Deepak Gupta Tested-by: Andreas Korb # QEMU, custom CVA6 Tested-by: Valentin Haudiquet Link: https://patch.msgid.link/20251112-v5_user_cfi_series-v23-23-b55691eacf4f@rivosinc.com [pjw@kernel.org: cleaned up patch description, issues reported by checkpatch] Signed-off-by: Paul Walmsley --- arch/riscv/Makefile | 5 ++- arch/riscv/include/asm/assembler.h | 44 ++++++++++++++++++++++ arch/riscv/kernel/vdso/Makefile | 11 +++++- arch/riscv/kernel/vdso/flush_icache.S | 4 ++ arch/riscv/kernel/vdso/getcpu.S | 4 ++ arch/riscv/kernel/vdso/note.S | 3 ++ arch/riscv/kernel/vdso/rt_sigreturn.S | 4 ++ arch/riscv/kernel/vdso/sys_hwprobe.S | 4 ++ arch/riscv/kernel/vdso/vgetrandom-chacha.S | 5 ++- 9 files changed, 81 insertions(+), 3 deletions(-) diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index 4c6de57f65ef0..41385bce8cc7e 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -81,9 +81,12 @@ riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZACAS) := $(riscv-march-y)_zacas # Check if the toolchain supports Zabha riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZABHA) := $(riscv-march-y)_zabha +KBUILD_BASE_ISA = -march=$(shell echo $(riscv-march-y) | sed -E 's/(rv32ima|rv64ima)fd([^v_]*)v?/\1\2/') +export KBUILD_BASE_ISA + # Remove F,D,V from isa string for all. Keep extensions between "fd" and "v" by # matching non-v and non-multi-letter extensions out with the filter ([^v_]*) -KBUILD_CFLAGS += -march=$(shell echo $(riscv-march-y) | sed -E 's/(rv32ima|rv64ima)fd([^v_]*)v?/\1\2/') +KBUILD_CFLAGS += $(KBUILD_BASE_ISA) KBUILD_AFLAGS += -march=$(riscv-march-y) diff --git a/arch/riscv/include/asm/assembler.h b/arch/riscv/include/asm/assembler.h index 16931712beab6..a8df1999118bf 100644 --- a/arch/riscv/include/asm/assembler.h +++ b/arch/riscv/include/asm/assembler.h @@ -80,3 +80,47 @@ .endm #endif /* __ASM_ASSEMBLER_H */ + +#if defined(VDSO_CFI) && (__riscv_xlen == 64) +.macro vdso_lpad, label = 0 +lpad \label +.endm +#else +.macro vdso_lpad, label = 0 +.endm +#endif + +/* + * This macro emits a program property note section identifying + * architecture features which require special handling, mainly for + * use in assembly files included in the VDSO. + */ +#define NT_GNU_PROPERTY_TYPE_0 5 +#define GNU_PROPERTY_RISCV_FEATURE_1_AND 0xc0000000 + +#define GNU_PROPERTY_RISCV_FEATURE_1_ZICFILP BIT(0) +#define GNU_PROPERTY_RISCV_FEATURE_1_ZICFISS BIT(1) + +#if defined(VDSO_CFI) && (__riscv_xlen == 64) +#define GNU_PROPERTY_RISCV_FEATURE_1_DEFAULT \ + (GNU_PROPERTY_RISCV_FEATURE_1_ZICFILP | GNU_PROPERTY_RISCV_FEATURE_1_ZICFISS) +#endif + +#ifdef GNU_PROPERTY_RISCV_FEATURE_1_DEFAULT +.macro emit_riscv_feature_1_and, feat = GNU_PROPERTY_RISCV_FEATURE_1_DEFAULT + .pushsection .note.gnu.property, "a" + .p2align 3 + .word 4 + .word 16 + .word NT_GNU_PROPERTY_TYPE_0 + .asciz "GNU" + .word GNU_PROPERTY_RISCV_FEATURE_1_AND + .word 4 + .word \feat + .word 0 + .popsection +.endm +#else +.macro emit_riscv_feature_1_and, feat = 0 +.endm +#endif diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile index 9ebb5e590f93a..272f1d837a80e 100644 --- a/arch/riscv/kernel/vdso/Makefile +++ b/arch/riscv/kernel/vdso/Makefile @@ -17,6 +17,11 @@ ifdef CONFIG_VDSO_GETRANDOM vdso-syms += getrandom endif +ifdef VDSO_CFI_BUILD +CFI_MARCH = _zicfilp_zicfiss +CFI_FULL = -fcf-protection=full +endif + # Files to link into the vdso obj-vdso = $(patsubst %, %.o, $(vdso-syms)) note.o @@ -27,6 +32,10 @@ endif ccflags-y := -fno-stack-protector ccflags-y += -DDISABLE_BRANCH_PROFILING ccflags-y += -fno-builtin +ccflags-y += $(KBUILD_BASE_ISA)$(CFI_MARCH) +ccflags-y += $(CFI_FULL) +asflags-y += $(KBUILD_BASE_ISA)$(CFI_MARCH) +asflags-y += $(CFI_FULL) ifneq ($(c-gettimeofday-y),) CFLAGS_vgettimeofday.o += -fPIC -include $(c-gettimeofday-y) @@ -79,7 +88,7 @@ include/generated/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE # The DSO images are built using a special linker script # Make sure only to export the intended __vdso_xxx symbol offsets. quiet_cmd_vdsold_and_check = VDSOLD $@ - cmd_vdsold_and_check = $(LD) $(ld_flags) -T $(filter-out FORCE,$^) -o $@.tmp && \ + cmd_vdsold_and_check = $(LD) $(CFI_FULL) $(ld_flags) -T $(filter-out FORCE,$^) -o $@.tmp && \ $(OBJCOPY) $(patsubst %, -G __vdso_%, $(vdso-syms)) $@.tmp $@ && \ rm $@.tmp && \ $(cmd_vdso_check) diff --git a/arch/riscv/kernel/vdso/flush_icache.S b/arch/riscv/kernel/vdso/flush_icache.S index 8f884227e8bca..e4c56970905e9 100644 --- a/arch/riscv/kernel/vdso/flush_icache.S +++ b/arch/riscv/kernel/vdso/flush_icache.S @@ -5,11 +5,13 @@ #include #include +#include .text /* int __vdso_flush_icache(void *start, void *end, unsigned long flags); */ SYM_FUNC_START(__vdso_flush_icache) .cfi_startproc + vdso_lpad #ifdef CONFIG_SMP li a7, __NR_riscv_flush_icache ecall @@ -20,3 +22,5 @@ SYM_FUNC_START(__vdso_flush_icache) ret .cfi_endproc SYM_FUNC_END(__vdso_flush_icache) + +emit_riscv_feature_1_and diff --git a/arch/riscv/kernel/vdso/getcpu.S b/arch/riscv/kernel/vdso/getcpu.S index 9c1bd531907f2..5c1ecc4e14654 100644 --- a/arch/riscv/kernel/vdso/getcpu.S +++ b/arch/riscv/kernel/vdso/getcpu.S @@ -5,14 +5,18 @@ #include #include +#include .text /* int __vdso_getcpu(unsigned *cpu, unsigned *node, void *unused); */ SYM_FUNC_START(__vdso_getcpu) .cfi_startproc + vdso_lpad /* For now, just do the syscall. */ li a7, __NR_getcpu ecall ret .cfi_endproc SYM_FUNC_END(__vdso_getcpu) + +emit_riscv_feature_1_and diff --git a/arch/riscv/kernel/vdso/note.S b/arch/riscv/kernel/vdso/note.S index 2a956c9422111..3d92cc956b95b 100644 --- a/arch/riscv/kernel/vdso/note.S +++ b/arch/riscv/kernel/vdso/note.S @@ -6,7 +6,10 @@ #include #include +#include ELFNOTE_START(Linux, 0, "a") .long LINUX_VERSION_CODE ELFNOTE_END + +emit_riscv_feature_1_and diff --git a/arch/riscv/kernel/vdso/rt_sigreturn.S b/arch/riscv/kernel/vdso/rt_sigreturn.S index 3dc022aa8931a..e82987dc37394 100644 --- a/arch/riscv/kernel/vdso/rt_sigreturn.S +++ b/arch/riscv/kernel/vdso/rt_sigreturn.S @@ -5,12 +5,16 @@ #include #include +#include .text SYM_FUNC_START(__vdso_rt_sigreturn) .cfi_startproc .cfi_signal_frame + vdso_lpad li a7, __NR_rt_sigreturn ecall .cfi_endproc SYM_FUNC_END(__vdso_rt_sigreturn) + +emit_riscv_feature_1_and diff --git a/arch/riscv/kernel/vdso/sys_hwprobe.S b/arch/riscv/kernel/vdso/sys_hwprobe.S index 77e57f8305216..f1694451a60c0 100644 --- a/arch/riscv/kernel/vdso/sys_hwprobe.S +++ b/arch/riscv/kernel/vdso/sys_hwprobe.S @@ -3,13 +3,17 @@ #include #include +#include .text SYM_FUNC_START(riscv_hwprobe) .cfi_startproc + vdso_lpad li a7, __NR_riscv_hwprobe ecall ret .cfi_endproc SYM_FUNC_END(riscv_hwprobe) + +emit_riscv_feature_1_and diff --git a/arch/riscv/kernel/vdso/vgetrandom-chacha.S b/arch/riscv/kernel/vdso/vgetrandom-chacha.S index 5f0dad8f2373e..916ab30a88f77 100644 --- a/arch/riscv/kernel/vdso/vgetrandom-chacha.S +++ b/arch/riscv/kernel/vdso/vgetrandom-chacha.S @@ -7,6 +7,7 @@ #include #include +#include .text @@ -74,7 +75,7 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack) #define _20 20, 20, 20, 20 #define _24 24, 24, 24, 24 #define _25 25, 25, 25, 25 - + vdso_lpad /* * The ABI requires s0-s9 saved. * This does not violate the stack-less requirement: no sensitive data @@ -247,3 +248,5 @@ SYM_FUNC_START(__arch_chacha20_blocks_nostack) ret SYM_FUNC_END(__arch_chacha20_blocks_nostack) + +emit_riscv_feature_1_and -- 2.47.3