Messages in this thread | | | Subject | Re: [PATCH bpf-next] riscv, bpf: fix some compiler error | From | tongtiangen <> | Date | Wed, 3 Nov 2021 11:06:31 +0800 |
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On 2021/11/2 23:45, Björn Töpel wrote: > On Tue, 2 Nov 2021 at 15:40, Tong Tiangen <tongtiangen@huawei.com> wrote: >> >> This patch fix two compile errors: >> 1. when CONFIG_BPF_JIT and CONFIG_ARCH_32I is open, There is the following >> compiler error: >> error: undefined symbol: rv_bpf_fixup_exception >> > > Good catch for the RV32! > >> 2. when CONFIG_BPF_JIT and CONFIG_ARCH_64I is open, There is the following >> compiler error (W=1): >> error: no previous prototype for 'rv_bpf_fixup_exception' >> >> In this patch, asm/extable.h is introduced, the rv_bpf_fixup_exception >> function declaration is added to this file. in addition, the definition of >> exception_table_entry is moved from asm-generic/extable.h to this file. >> > > This is way too complicated. More below. > >> Fixes: 252c765bd764 ("riscv, bpf: Add BPF exception tables") >> Signed-off-by: Tong Tiangen <tongtiangen@huawei.com> >> --- >> arch/riscv/include/asm/Kbuild | 1 - >> arch/riscv/include/asm/extable.h | 49 ++++++++++++++++++++++++++++++++ >> arch/riscv/include/asm/uaccess.h | 13 --------- >> arch/riscv/mm/extable.c | 8 +----- >> 4 files changed, 50 insertions(+), 21 deletions(-) >> create mode 100644 arch/riscv/include/asm/extable.h >> >> diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild >> index 445ccc97305a..57b86fd9916c 100644 >> --- a/arch/riscv/include/asm/Kbuild >> +++ b/arch/riscv/include/asm/Kbuild >> @@ -1,6 +1,5 @@ >> # SPDX-License-Identifier: GPL-2.0 >> generic-y += early_ioremap.h >> -generic-y += extable.h >> generic-y += flat.h >> generic-y += kvm_para.h >> generic-y += user.h >> diff --git a/arch/riscv/include/asm/extable.h b/arch/riscv/include/asm/extable.h >> new file mode 100644 >> index 000000000000..aa0332b053fb >> --- /dev/null >> +++ b/arch/riscv/include/asm/extable.h >> @@ -0,0 +1,49 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +#ifndef __ASM_EXTABLE_H >> +#define __ASM_EXTABLE_H >> + >> +/* >> + * The exception table consists of pairs of addresses: the first is the >> + * address of an instruction that is allowed to fault, and the second is >> + * the address at which the program should continue. No registers are >> + * modified, so it is entirely up to the continuation code to figure out >> + * what to do. >> + * >> + * All the routines below use bits of fixup code that are out of line >> + * with the main instruction path. This means when everything is well, >> + * we don't even have to jump over them. Further, they do not intrude >> + * on our cache or tlb entries. >> + */ >> +struct exception_table_entry { >> + unsigned long insn, fixup; >> +}; >> + >> +struct pt_regs; >> +int fixup_exception(struct pt_regs *regs); >> + >> +#if defined(CONFIG_MMU) >> +static inline bool rv_in_bpf_jit(struct pt_regs *regs) >> +{ >> + if (!IS_ENABLED(CONFIG_BPF_JIT) || !IS_ENABLED(CONFIG_64BIT)) >> + return false; >> + >> + return regs->epc >= BPF_JIT_REGION_START && regs->epc < BPF_JIT_REGION_END; >> +} >> +#else >> +static inline bool rv_in_bpf_jit(struct pt_regs *regs) >> +{ >> + return false; >> +} >> +#endif >> + >> +#if defined(CONFIG_BPF_JIT) && defined(CONFIG_64BIT) >> +int rv_bpf_fixup_exception(const struct exception_table_entry *ex, struct pt_regs *regs); >> +#else >> +static inline int rv_bpf_fixup_exception(const struct exception_table_entry *ex, >> + struct pt_regs *regs) >> +{ >> + return 0; >> +} >> +#endif >> + >> +#endif >> diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h >> index f314ff44c48d..96ea91dc0e9c 100644 >> --- a/arch/riscv/include/asm/uaccess.h >> +++ b/arch/riscv/include/asm/uaccess.h >> @@ -56,19 +56,6 @@ static inline int __access_ok(unsigned long addr, unsigned long size) >> return size <= TASK_SIZE && addr <= TASK_SIZE - size; >> } >> >> -/* >> - * The exception table consists of pairs of addresses: the first is the >> - * address of an instruction that is allowed to fault, and the second is >> - * the address at which the program should continue. No registers are >> - * modified, so it is entirely up to the continuation code to figure out >> - * what to do. >> - * >> - * All the routines below use bits of fixup code that are out of line >> - * with the main instruction path. This means when everything is well, >> - * we don't even have to jump over them. Further, they do not intrude >> - * on our cache or tlb entries. >> - */ >> - >> #define __LSW 0 >> #define __MSW 1 >> >> diff --git a/arch/riscv/mm/extable.c b/arch/riscv/mm/extable.c >> index 18bf338303b6..264f465db5bb 100644 >> --- a/arch/riscv/mm/extable.c >> +++ b/arch/riscv/mm/extable.c >> @@ -11,10 +11,6 @@ >> #include <linux/module.h> >> #include <linux/uaccess.h> >> >> -#ifdef CONFIG_BPF_JIT >> -int rv_bpf_fixup_exception(const struct exception_table_entry *ex, struct pt_regs *regs); >> -#endif >> - >> int fixup_exception(struct pt_regs *regs) >> { >> const struct exception_table_entry *fixup; >> @@ -23,10 +19,8 @@ int fixup_exception(struct pt_regs *regs) >> if (!fixup) >> return 0; >> >> -#ifdef CONFIG_BPF_JIT >> - if (regs->epc >= BPF_JIT_REGION_START && regs->epc < BPF_JIT_REGION_END) >> + if (rv_in_bpf_jit(regs)) >> return rv_bpf_fixup_exception(fixup, regs); >> -#endif >> > > The only changes that are needed are: > 1. Simply gate with CONFIG_BPF_JIT && CONFIG_ARCH_RV64I, instead of of > CONFIG_BPF_JIT > > 2. Forward declaration of the rv_bpf_fixup_exception() in bpf_jit_comp64.c. > Hi Björn: From the perspective of development, introduce asm/extable.h is also prepare for the subsequent modification of exception_table_entry, such as: 1. https://lkml.org/lkml/2021/10/20/591 2. https://lore.kernel.org/linux-arm-kernel/20211019160219.5202-11-mark.rutland@arm.com/
Therefore, the prototype declarations and definitions related to kernel config are placed in head file, which can avoid compiler error and simplify the rendering of functions.
Thanks. Tong.
> > Björn > . >
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