diff mbox series

[v11,23/27] arch/riscv: compile vdso with landing pad

Message ID 20250310-v5_user_cfi_series-v11-23-86b36cbfb910@rivosinc.com (mailing list archive)
State New
Headers show
Series riscv control-flow integrity for usermode | expand

Commit Message

Deepak Gupta March 10, 2025, 2:52 p.m. UTC 
From: Jim Shu <jim.shu@sifive.com>

user mode tasks compiled with zicfilp may call indirectly into vdso (like
hwprobe indirect calls). Add landing pad compile support in vdso. vdso
with landing pad in it will be nop for tasks which have not enabled
landing pad.
This patch allows to run user mode tasks with cfi eanbled and do no harm.

Future work can be done on this to do below
 - labeled landing pad on vdso functions (whenever labeling support shows
   up in gnu-toolchain)
 - emit shadow stack instructions only in vdso compiled objects as part of
   kernel compile.

Signed-off-by: Jim Shu <jim.shu@sifive.com>
Signed-off-by: Deepak Gupta <debug@rivosinc.com>
---
 arch/riscv/Makefile                   |  7 +++++-
 arch/riscv/include/asm/assembler.h    | 44 +++++++++++++++++++++++++++++++++++
 arch/riscv/kernel/vdso/Makefile       | 12 ++++++++++
 arch/riscv/kernel/vdso/flush_icache.S |  4 ++++
 arch/riscv/kernel/vdso/getcpu.S       |  4 ++++
 arch/riscv/kernel/vdso/rt_sigreturn.S |  4 ++++
 arch/riscv/kernel/vdso/sys_hwprobe.S  |  4 ++++
 7 files changed, 78 insertions(+), 1 deletion(-)

Comments

Zong Li March 14, 2025, 7:37 a.m. UTC | #1 
On Mon, Mar 10, 2025 at 11:44 PM Deepak Gupta <debug@rivosinc.com> wrote:
>
> From: Jim Shu <jim.shu@sifive.com>
>
> user mode tasks compiled with zicfilp may call indirectly into vdso (like
> hwprobe indirect calls). Add landing pad compile support in vdso. vdso
> with landing pad in it will be nop for tasks which have not enabled
> landing pad.
> This patch allows to run user mode tasks with cfi eanbled and do no harm.
>
> Future work can be done on this to do below
>  - labeled landing pad on vdso functions (whenever labeling support shows
>    up in gnu-toolchain)
>  - emit shadow stack instructions only in vdso compiled objects as part of
>    kernel compile.
>
> Signed-off-by: Jim Shu <jim.shu@sifive.com>
> Signed-off-by: Deepak Gupta <debug@rivosinc.com>
> ---
>  arch/riscv/Makefile                   |  7 +++++-
>  arch/riscv/include/asm/assembler.h    | 44 +++++++++++++++++++++++++++++++++++
>  arch/riscv/kernel/vdso/Makefile       | 12 ++++++++++
>  arch/riscv/kernel/vdso/flush_icache.S |  4 ++++
>  arch/riscv/kernel/vdso/getcpu.S       |  4 ++++
>  arch/riscv/kernel/vdso/rt_sigreturn.S |  4 ++++
>  arch/riscv/kernel/vdso/sys_hwprobe.S  |  4 ++++
>  7 files changed, 78 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index 13fbc0f94238..ea9468af2cb4 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -87,10 +87,15 @@ riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZACAS) := $(riscv-march-y)_zacas
>
>  # Check if the toolchain supports Zabha
>  riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZABHA) := $(riscv-march-y)_zabha
> +# Check if the toolchain supports Zihintpause extension
> +riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZIHINTPAUSE) := $(riscv-march-y)_zihintpause

I think we don't need this, it has removed by the '6da111574baf
("riscv: Provide a definition for 'pause'")'. Apart from that, this
patch looks good to me.

Reviewed-by: Zong Li <zong.li@sifive.com>

> +
> +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 44b1457d3e95..a058ea5e9c58 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(CONFIG_RISCV_USER_CFI) && (__riscv_xlen == 64)
> +.macro vdso_lpad
> +lpad 0
> +.endm
> +#else
> +.macro vdso_lpad
> +.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      (1U << 0)
> +#define GNU_PROPERTY_RISCV_FEATURE_1_ZICFISS      (1U << 1)
> +
> +#if defined(CONFIG_RISCV_USER_CFI) && (__riscv_xlen == 64)
> +#define GNU_PROPERTY_RISCV_FEATURE_1_DEFAULT \
> +       (GNU_PROPERTY_RISCV_FEATURE_1_ZICFILP)
> +#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 9a1b555e8733..daa10c2b0dd1 100644
> --- a/arch/riscv/kernel/vdso/Makefile
> +++ b/arch/riscv/kernel/vdso/Makefile
> @@ -13,12 +13,18 @@ vdso-syms += flush_icache
>  vdso-syms += hwprobe
>  vdso-syms += sys_hwprobe
>
> +ifdef CONFIG_RISCV_USER_CFI
> +LPAD_MARCH = _zicfilp
> +endif
> +
>  # Files to link into the vdso
>  obj-vdso = $(patsubst %, %.o, $(vdso-syms)) note.o
>
>  ccflags-y := -fno-stack-protector
>  ccflags-y += -DDISABLE_BRANCH_PROFILING
>  ccflags-y += -fno-builtin
> +ccflags-y += $(KBUILD_BASE_ISA)$(LPAD_MARCH)
> +asflags-y += $(KBUILD_BASE_ISA)$(LPAD_MARCH)
>
>  ifneq ($(c-gettimeofday-y),)
>    CFLAGS_vgettimeofday.o += -fPIC -include $(c-gettimeofday-y)
> @@ -40,6 +46,12 @@ endif
>  CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS)
>  CFLAGS_REMOVE_hwprobe.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS)
>
> +# Disable profiling and instrumentation for VDSO code
> +GCOV_PROFILE := n
> +KCOV_INSTRUMENT := n
> +KASAN_SANITIZE := n
> +UBSAN_SANITIZE := n
> +
>  # Force dependency
>  $(obj)/vdso.o: $(obj)/vdso.so
>
> diff --git a/arch/riscv/kernel/vdso/flush_icache.S b/arch/riscv/kernel/vdso/flush_icache.S
> index 8f884227e8bc..e4c56970905e 100644
> --- a/arch/riscv/kernel/vdso/flush_icache.S
> +++ b/arch/riscv/kernel/vdso/flush_icache.S
> @@ -5,11 +5,13 @@
>
>  #include <linux/linkage.h>
>  #include <asm/unistd.h>
> +#include <asm/assembler.h>
>
>         .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 9c1bd531907f..5c1ecc4e1465 100644
> --- a/arch/riscv/kernel/vdso/getcpu.S
> +++ b/arch/riscv/kernel/vdso/getcpu.S
> @@ -5,14 +5,18 @@
>
>  #include <linux/linkage.h>
>  #include <asm/unistd.h>
> +#include <asm/assembler.h>
>
>         .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/rt_sigreturn.S b/arch/riscv/kernel/vdso/rt_sigreturn.S
> index 3dc022aa8931..e82987dc3739 100644
> --- a/arch/riscv/kernel/vdso/rt_sigreturn.S
> +++ b/arch/riscv/kernel/vdso/rt_sigreturn.S
> @@ -5,12 +5,16 @@
>
>  #include <linux/linkage.h>
>  #include <asm/unistd.h>
> +#include <asm/assembler.h>
>
>         .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 77e57f830521..f1694451a60c 100644
> --- a/arch/riscv/kernel/vdso/sys_hwprobe.S
> +++ b/arch/riscv/kernel/vdso/sys_hwprobe.S
> @@ -3,13 +3,17 @@
>
>  #include <linux/linkage.h>
>  #include <asm/unistd.h>
> +#include <asm/assembler.h>
>
>  .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
>
> --
> 2.34.1
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
diff mbox series

Patch

diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 13fbc0f94238..ea9468af2cb4 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -87,10 +87,15 @@  riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZACAS) := $(riscv-march-y)_zacas
 
 # Check if the toolchain supports Zabha
 riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZABHA) := $(riscv-march-y)_zabha
+# Check if the toolchain supports Zihintpause extension
+riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZIHINTPAUSE) := $(riscv-march-y)_zihintpause
+
+KBUILD_BASE_ISA = -march=$(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 44b1457d3e95..a058ea5e9c58 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(CONFIG_RISCV_USER_CFI) && (__riscv_xlen == 64)
+.macro vdso_lpad
+lpad 0
+.endm
+#else
+.macro vdso_lpad
+.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      (1U << 0)
+#define GNU_PROPERTY_RISCV_FEATURE_1_ZICFISS      (1U << 1)
+
+#if defined(CONFIG_RISCV_USER_CFI) && (__riscv_xlen == 64)
+#define GNU_PROPERTY_RISCV_FEATURE_1_DEFAULT \
+	(GNU_PROPERTY_RISCV_FEATURE_1_ZICFILP)
+#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 9a1b555e8733..daa10c2b0dd1 100644
--- a/arch/riscv/kernel/vdso/Makefile
+++ b/arch/riscv/kernel/vdso/Makefile
@@ -13,12 +13,18 @@  vdso-syms += flush_icache
 vdso-syms += hwprobe
 vdso-syms += sys_hwprobe
 
+ifdef CONFIG_RISCV_USER_CFI
+LPAD_MARCH = _zicfilp
+endif
+
 # Files to link into the vdso
 obj-vdso = $(patsubst %, %.o, $(vdso-syms)) note.o
 
 ccflags-y := -fno-stack-protector
 ccflags-y += -DDISABLE_BRANCH_PROFILING
 ccflags-y += -fno-builtin
+ccflags-y += $(KBUILD_BASE_ISA)$(LPAD_MARCH)
+asflags-y += $(KBUILD_BASE_ISA)$(LPAD_MARCH)
 
 ifneq ($(c-gettimeofday-y),)
   CFLAGS_vgettimeofday.o += -fPIC -include $(c-gettimeofday-y)
@@ -40,6 +46,12 @@  endif
 CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS)
 CFLAGS_REMOVE_hwprobe.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS)
 
+# Disable profiling and instrumentation for VDSO code
+GCOV_PROFILE := n
+KCOV_INSTRUMENT := n
+KASAN_SANITIZE := n
+UBSAN_SANITIZE := n
+
 # Force dependency
 $(obj)/vdso.o: $(obj)/vdso.so
 
diff --git a/arch/riscv/kernel/vdso/flush_icache.S b/arch/riscv/kernel/vdso/flush_icache.S
index 8f884227e8bc..e4c56970905e 100644
--- a/arch/riscv/kernel/vdso/flush_icache.S
+++ b/arch/riscv/kernel/vdso/flush_icache.S
@@ -5,11 +5,13 @@ 
 
 #include <linux/linkage.h>
 #include <asm/unistd.h>
+#include <asm/assembler.h>
 
 	.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 9c1bd531907f..5c1ecc4e1465 100644
--- a/arch/riscv/kernel/vdso/getcpu.S
+++ b/arch/riscv/kernel/vdso/getcpu.S
@@ -5,14 +5,18 @@ 
 
 #include <linux/linkage.h>
 #include <asm/unistd.h>
+#include <asm/assembler.h>
 
 	.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/rt_sigreturn.S b/arch/riscv/kernel/vdso/rt_sigreturn.S
index 3dc022aa8931..e82987dc3739 100644
--- a/arch/riscv/kernel/vdso/rt_sigreturn.S
+++ b/arch/riscv/kernel/vdso/rt_sigreturn.S
@@ -5,12 +5,16 @@ 
 
 #include <linux/linkage.h>
 #include <asm/unistd.h>
+#include <asm/assembler.h>
 
 	.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 77e57f830521..f1694451a60c 100644
--- a/arch/riscv/kernel/vdso/sys_hwprobe.S
+++ b/arch/riscv/kernel/vdso/sys_hwprobe.S
@@ -3,13 +3,17 @@ 
 
 #include <linux/linkage.h>
 #include <asm/unistd.h>
+#include <asm/assembler.h>
 
 .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