| Message ID | 20230811233556.97161-8-samitolvanen@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | riscv: SCS support | expand |
Hi Sami, kernel test robot noticed the following build errors: [auto build test ERROR on 52a93d39b17dc7eb98b6aa3edb93943248e03b2f] url: https://github.com/intel-lab-lkp/linux/commits/Sami-Tolvanen/riscv-VMAP_STACK-overflow-detection-thread-safe/20230812-073751 base: 52a93d39b17dc7eb98b6aa3edb93943248e03b2f patch link: https://lore.kernel.org/r/20230811233556.97161-8-samitolvanen%40google.com patch subject: [PATCH 1/5] riscv: VMAP_STACK overflow detection thread-safe config: riscv-randconfig-r042-20230812 (https://download.01.org/0day-ci/archive/20230812/202308122238.XLMMmeL0-lkp@intel.com/config) compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a) reproduce: (https://download.01.org/0day-ci/archive/20230812/202308122238.XLMMmeL0-lkp@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@intel.com> | Closes: https://lore.kernel.org/oe-kbuild-all/202308122238.XLMMmeL0-lkp@intel.com/ All errors (new ones prefixed by >>): >> ld.lld: error: undefined symbol: __per_cpu_offset >>> referenced by arch/riscv/kernel/entry.o:(handle_kernel_stack_overflow) in archive vmlinux.a
On Sat, Aug 12, 2023 at 10:36 PM kernel test robot <lkp@intel.com> wrote: > > Hi Sami, > > kernel test robot noticed the following build errors: > > [auto build test ERROR on 52a93d39b17dc7eb98b6aa3edb93943248e03b2f] > > url: https://github.com/intel-lab-lkp/linux/commits/Sami-Tolvanen/riscv-VMAP_STACK-overflow-detection-thread-safe/20230812-073751 > base: 52a93d39b17dc7eb98b6aa3edb93943248e03b2f > patch link: https://lore.kernel.org/r/20230811233556.97161-8-samitolvanen%40google.com > patch subject: [PATCH 1/5] riscv: VMAP_STACK overflow detection thread-safe > config: riscv-randconfig-r042-20230812 (https://download.01.org/0day-ci/archive/20230812/202308122238.XLMMmeL0-lkp@intel.com/config) > compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a) > reproduce: (https://download.01.org/0day-ci/archive/20230812/202308122238.XLMMmeL0-lkp@intel.com/reproduce) > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot <lkp@intel.com> > | Closes: https://lore.kernel.org/oe-kbuild-all/202308122238.XLMMmeL0-lkp@intel.com/ > > All errors (new ones prefixed by >>): > > >> ld.lld: error: undefined symbol: __per_cpu_offset > >>> referenced by arch/riscv/kernel/entry.o:(handle_kernel_stack_overflow) in archive vmlinux.a !CONFIG_SMP missed > > -- > 0-DAY CI Kernel Test Service > https://github.com/intel/lkp-tests/wiki
On Sat, Aug 12, 2023 at 6:25 PM Guo Ren <guoren@kernel.org> wrote: > > On Sat, Aug 12, 2023 at 10:36 PM kernel test robot <lkp@intel.com> wrote: > > > > Hi Sami, > > > > kernel test robot noticed the following build errors: > > > > [auto build test ERROR on 52a93d39b17dc7eb98b6aa3edb93943248e03b2f] > > > > url: https://github.com/intel-lab-lkp/linux/commits/Sami-Tolvanen/riscv-VMAP_STACK-overflow-detection-thread-safe/20230812-073751 > > base: 52a93d39b17dc7eb98b6aa3edb93943248e03b2f > > patch link: https://lore.kernel.org/r/20230811233556.97161-8-samitolvanen%40google.com > > patch subject: [PATCH 1/5] riscv: VMAP_STACK overflow detection thread-safe > > config: riscv-randconfig-r042-20230812 (https://download.01.org/0day-ci/archive/20230812/202308122238.XLMMmeL0-lkp@intel.com/config) > > compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a) > > reproduce: (https://download.01.org/0day-ci/archive/20230812/202308122238.XLMMmeL0-lkp@intel.com/reproduce) > > > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > > the same patch/commit), kindly add following tags > > | Reported-by: kernel test robot <lkp@intel.com> > > | Closes: https://lore.kernel.org/oe-kbuild-all/202308122238.XLMMmeL0-lkp@intel.com/ > > > > All errors (new ones prefixed by >>): > > > > >> ld.lld: error: undefined symbol: __per_cpu_offset > > >>> referenced by arch/riscv/kernel/entry.o:(handle_kernel_stack_overflow) in archive vmlinux.a > !CONFIG_SMP missed Indeed. I'll fix this in v2. Sami
diff --git a/arch/riscv/include/asm/asm.h b/arch/riscv/include/asm/asm.h index 114bbadaef41..f403e46e04f2 100644 --- a/arch/riscv/include/asm/asm.h +++ b/arch/riscv/include/asm/asm.h @@ -82,6 +82,22 @@ .endr .endm +#ifdef CONFIG_32BIT +#define PER_CPU_OFFSET_SHIFT 2 +#else +#define PER_CPU_OFFSET_SHIFT 3 +#endif + +.macro asm_per_cpu dst sym tmp + REG_L \tmp, TASK_TI_CPU_NUM(tp) + slli \tmp, \tmp, PER_CPU_OFFSET_SHIFT + la \dst, __per_cpu_offset + add \dst, \dst, \tmp + REG_L \tmp, 0(\dst) + la \dst, \sym + add \dst, \dst, \tmp +.endm + /* save all GPs except x1 ~ x5 */ .macro save_from_x6_to_x31 REG_S x6, PT_T1(sp) diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h index 1833beb00489..d18ce0113ca1 100644 --- a/arch/riscv/include/asm/thread_info.h +++ b/arch/riscv/include/asm/thread_info.h @@ -34,9 +34,6 @@ #ifndef __ASSEMBLY__ -extern long shadow_stack[SHADOW_OVERFLOW_STACK_SIZE / sizeof(long)]; -extern unsigned long spin_shadow_stack; - #include <asm/processor.h> #include <asm/csr.h> diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c index d6a75aac1d27..9f535d5de33f 100644 --- a/arch/riscv/kernel/asm-offsets.c +++ b/arch/riscv/kernel/asm-offsets.c @@ -39,6 +39,7 @@ void asm_offsets(void) OFFSET(TASK_TI_KERNEL_SP, task_struct, thread_info.kernel_sp); OFFSET(TASK_TI_USER_SP, task_struct, thread_info.user_sp); + OFFSET(TASK_TI_CPU_NUM, task_struct, thread_info.cpu); OFFSET(TASK_THREAD_F0, task_struct, thread.fstate.f[0]); OFFSET(TASK_THREAD_F1, task_struct, thread.fstate.f[1]); OFFSET(TASK_THREAD_F2, task_struct, thread.fstate.f[2]); diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 143a2bb3e697..3d11aa3af105 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -10,9 +10,11 @@ #include <asm/asm.h> #include <asm/csr.h> #include <asm/unistd.h> +#include <asm/page.h> #include <asm/thread_info.h> #include <asm/asm-offsets.h> #include <asm/errata_list.h> +#include <linux/sizes.h> SYM_CODE_START(handle_exception) /* @@ -170,67 +172,15 @@ SYM_CODE_END(ret_from_exception) #ifdef CONFIG_VMAP_STACK SYM_CODE_START_LOCAL(handle_kernel_stack_overflow) - /* - * Takes the psuedo-spinlock for the shadow stack, in case multiple - * harts are concurrently overflowing their kernel stacks. We could - * store any value here, but since we're overflowing the kernel stack - * already we only have SP to use as a scratch register. So we just - * swap in the address of the spinlock, as that's definately non-zero. - * - * Pairs with a store_release in handle_bad_stack(). - */ -1: la sp, spin_shadow_stack - REG_AMOSWAP_AQ sp, sp, (sp) - bnez sp, 1b - - la sp, shadow_stack - addi sp, sp, SHADOW_OVERFLOW_STACK_SIZE - - //save caller register to shadow stack - addi sp, sp, -(PT_SIZE_ON_STACK) - REG_S x1, PT_RA(sp) - REG_S x5, PT_T0(sp) - REG_S x6, PT_T1(sp) - REG_S x7, PT_T2(sp) - REG_S x10, PT_A0(sp) - REG_S x11, PT_A1(sp) - REG_S x12, PT_A2(sp) - REG_S x13, PT_A3(sp) - REG_S x14, PT_A4(sp) - REG_S x15, PT_A5(sp) - REG_S x16, PT_A6(sp) - REG_S x17, PT_A7(sp) - REG_S x28, PT_T3(sp) - REG_S x29, PT_T4(sp) - REG_S x30, PT_T5(sp) - REG_S x31, PT_T6(sp) - - la ra, restore_caller_reg - tail get_overflow_stack - -restore_caller_reg: - //save per-cpu overflow stack - REG_S a0, -8(sp) - //restore caller register from shadow_stack - REG_L x1, PT_RA(sp) - REG_L x5, PT_T0(sp) - REG_L x6, PT_T1(sp) - REG_L x7, PT_T2(sp) - REG_L x10, PT_A0(sp) - REG_L x11, PT_A1(sp) - REG_L x12, PT_A2(sp) - REG_L x13, PT_A3(sp) - REG_L x14, PT_A4(sp) - REG_L x15, PT_A5(sp) - REG_L x16, PT_A6(sp) - REG_L x17, PT_A7(sp) - REG_L x28, PT_T3(sp) - REG_L x29, PT_T4(sp) - REG_L x30, PT_T5(sp) - REG_L x31, PT_T6(sp) + /* we reach here from kernel context, sscratch must be 0 */ + csrrw x31, CSR_SCRATCH, x31 + asm_per_cpu sp, overflow_stack, x31 + li x31, OVERFLOW_STACK_SIZE + add sp, sp, x31 + /* zero out x31 again and restore x31 */ + xor x31, x31, x31 + csrrw x31, CSR_SCRATCH, x31 - //load per-cpu overflow stack - REG_L sp, -8(sp) addi sp, sp, -(PT_SIZE_ON_STACK) //save context to overflow stack diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index f910dfccbf5d..deb2144d9143 100644 --- a/arch/riscv/kernel/traps.c +++ b/arch/riscv/kernel/traps.c @@ -397,48 +397,14 @@ int is_valid_bugaddr(unsigned long pc) #endif /* CONFIG_GENERIC_BUG */ #ifdef CONFIG_VMAP_STACK -/* - * Extra stack space that allows us to provide panic messages when the kernel - * has overflowed its stack. - */ -static DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], +DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack)__aligned(16); -/* - * A temporary stack for use by handle_kernel_stack_overflow. This is used so - * we can call into C code to get the per-hart overflow stack. Usage of this - * stack must be protected by spin_shadow_stack. - */ -long shadow_stack[SHADOW_OVERFLOW_STACK_SIZE/sizeof(long)] __aligned(16); - -/* - * A pseudo spinlock to protect the shadow stack from being used by multiple - * harts concurrently. This isn't a real spinlock because the lock side must - * be taken without a valid stack and only a single register, it's only taken - * while in the process of panicing anyway so the performance and error - * checking a proper spinlock gives us doesn't matter. - */ -unsigned long spin_shadow_stack; - -asmlinkage unsigned long get_overflow_stack(void) -{ - return (unsigned long)this_cpu_ptr(overflow_stack) + - OVERFLOW_STACK_SIZE; -} asmlinkage void handle_bad_stack(struct pt_regs *regs) { unsigned long tsk_stk = (unsigned long)current->stack; unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack); - /* - * We're done with the shadow stack by this point, as we're on the - * overflow stack. Tell any other concurrent overflowing harts that - * they can proceed with panicing by releasing the pseudo-spinlock. - * - * This pairs with an amoswap.aq in handle_kernel_stack_overflow. - */ - smp_store_release(&spin_shadow_stack, 0); - console_verbose(); pr_emerg("Insufficient stack space to handle exception!\n");