On Sat, Oct 01, 2022 at 09:24:49PM -0400, guoren@xxxxxxxxxx wrote: > From: Dao Lu <daolu@xxxxxxxxxxxx> > > Add support for STACKLEAK gcc plugin to riscv by implementing > stackleak_check_alloca, based heavily on the arm64 version, and > modifying the entry.S. Additionally, this disables the plugin for EFI > stub code for riscv. All modifications base on generic_entry. I think this commit message is stale; `stackleak_check_alloca` doesn't exist any more. > Link: https://lore.kernel.org/linux-riscv/20220615213834.3116135-1-daolu@xxxxxxxxxxxx/ > Signed-off-by: Dao Lu <daolu@xxxxxxxxxxxx> > Co-developed-by: Xianting Tian <xianting.tian@xxxxxxxxxxxxxxxxx> > Signed-off-by: Xianting Tian <xianting.tian@xxxxxxxxxxxxxxxxx> > Co-developed-by: Guo Ren <guoren@xxxxxxxxxx> > Signed-off-by: Guo Ren <guoren@xxxxxxxxxx> > Cc: Conor Dooley <Conor.Dooley@xxxxxxxxxxxxx> > Cc: Mark Rutland <mark.rutland@xxxxxxx> > --- > arch/riscv/Kconfig | 1 + > arch/riscv/kernel/entry.S | 8 +++++++- > drivers/firmware/efi/libstub/Makefile | 2 +- > 3 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index dfe600f3526c..76bde12d9f8c 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -81,6 +81,7 @@ config RISCV > select HAVE_ARCH_MMAP_RND_BITS if MMU > select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT > select HAVE_ARCH_SECCOMP_FILTER > + select HAVE_ARCH_STACKLEAK > select HAVE_ARCH_TRACEHOOK > select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU > select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE > diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S > index 5f49517cd3a2..39097c1474a0 100644 > --- a/arch/riscv/kernel/entry.S > +++ b/arch/riscv/kernel/entry.S > @@ -130,7 +130,6 @@ END(handle_exception) > ENTRY(ret_from_exception) > REG_L s0, PT_STATUS(sp) > > - csrc CSR_STATUS, SR_IE > #ifdef CONFIG_RISCV_M_MODE > /* the MPP value is too large to be used as an immediate arg for addi */ > li t0, SR_MPP > @@ -139,6 +138,9 @@ ENTRY(ret_from_exception) > andi s0, s0, SR_SPP > #endif > bnez s0, 1f > +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK > + call stackleak_erase > +#endif I assume this can happen on an arbitrary stack, and so you can't use the stackleak_erase_{on,off}_task_stack variants? Just to check, have you given this a spin with LKDTM and the STACKLEAK_ERASING test? If not, it'd be good to test that (and ideally, put some sample output from that into the commit message). For example, as per: https://lore.kernel.org/all/20220427173128.2603085-1-mark.rutland@xxxxxxx/ ... on arm64 this looks something like: | # uname -a | Linux buildroot 5.18.0-rc1-00013-g26f638ab0d7c #3 SMP PREEMPT Wed Apr 27 16:21:37 BST 2022 aarch64 GNU/Linux | # echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT | lkdtm: Performing direct entry STACKLEAK_ERASING | lkdtm: stackleak stack usage: | high offset: 336 bytes | current: 688 bytes | lowest: 1232 bytes | tracked: 1232 bytes | untracked: 672 bytes | poisoned: 14136 bytes | low offset: 8 bytes | lkdtm: OK: the rest of the thread stack is properly erased Thanks, Mark. > > /* Save unwound kernel stack pointer in thread_info */ > addi s0, sp, PT_SIZE_ON_STACK > @@ -148,8 +150,12 @@ ENTRY(ret_from_exception) > * Save TP into the scratch register , so we can find the kernel data > * structures again. > */ > + csrc CSR_STATUS, SR_IE > csrw CSR_SCRATCH, tp > + j 2f > 1: > + csrc CSR_STATUS, SR_IE > +2: > /* > * The current load reservation is effectively part of the processor's > * state, in the sense that load reservations cannot be shared between > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile > index d0537573501e..5e1fc4f82883 100644 > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -25,7 +25,7 @@ cflags-$(CONFIG_ARM) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > -fno-builtin -fpic \ > $(call cc-option,-mno-single-pic-base) > cflags-$(CONFIG_RISCV) := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > - -fpic > + -fpic $(DISABLE_STACKLEAK_PLUGIN) > > cflags-$(CONFIG_EFI_GENERIC_STUB) += -I$(srctree)/scripts/dtc/libfdt > > -- > 2.36.1 >
