| Message ID | 20201106222512.52454-1-jolsa@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | pahole/kernel: Workaround dwarf bug for function encoding | expand |
On Fri, Nov 6, 2020 at 2:25 PM Jiri Olsa <jolsa@kernel.org> wrote: > > hi, > because of gcc bug [1] we can no longer rely on DW_AT_declaration > attribute to filter out declarations and end up with just > one copy of the function in the BTF data. > > It seems this bug is not easy to fix, but regardless if the > it's coming soon, it's probably good idea not to depend so > much only on dwarf data and make some extra checks. > > Thus for function encoding we are now doing following checks: > - argument names are defined for the function > - there's symbol and address defined for the function > - function address belongs to ftrace locations (new in v2) > - function is generated only once > > v4 changes: > - added acks > - renames and change functions_valid to be local var [Andrii] > - fixed error path (return err) of collect_symbols > > v3 changes: > - added Hao's ack for patch 1 > - fixed realloc memory leak [Andrii] > - fixed addrs_cmp function [Andrii] > - removed SET_SYMBOL macro [Andrii] > - fixed the 'valid' function logic > - added .init.bpf.preserve_type check > - added iterator functions to new kernel section > .init.bpf.preserve_type [Yonghong] > > v2 changes: > - add check ensuring functions belong to ftrace's mcount > locations, this way we ensure to have in BTF only > functions available for ftrace - patch 2 changelog > describes all details > - use collect* function names [Andrii] > - use conventional size increase in realloc [Andrii] > - drop elf_sym__is_function check > - drop patch 3, it's not needed, because we follow ftrace > locations > > thanks, > jirka > > > [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97060 > For the series: Acked-by: Andrii Nakryiko <andrii@kernel.org>
Em Fri, Nov 06, 2020 at 02:56:45PM -0800, Andrii Nakryiko escreveu: > On Fri, Nov 6, 2020 at 2:25 PM Jiri Olsa <jolsa@kernel.org> wrote: > For the series: > Acked-by: Andrii Nakryiko <andrii@kernel.org> Thanks, applied, testing now. - Arnaldo
Em Mon, Nov 09, 2020 at 02:29:11PM -0300, Arnaldo Carvalho de Melo escreveu: > Em Fri, Nov 06, 2020 at 02:56:45PM -0800, Andrii Nakryiko escreveu: > > On Fri, Nov 6, 2020 at 2:25 PM Jiri Olsa <jolsa@kernel.org> wrote: > > > For the series: > > > Acked-by: Andrii Nakryiko <andrii@kernel.org> > > Thanks, applied, testing now. Now we have: $ pfunct -F btf /sys/kernel/btf/vmlinux | wc -l 38816 $ pfunct -F btf /sys/kernel/btf/vmlinux | head get_e820_md5 relocate_restore_code resume_play_dead bsp_pm_callback msr_initialize_bdw msr_save_cpuid_features pm_check_save_msr amd_bus_cpu_online update_res pci_read $ $ pfunct -F btf /sys/kernel/btf/vmlinux -f msr_save_cpuid_features int msr_save_cpuid_features(const struct x86_cpu_id * c); $ $ pfunct -F btf /sys/kernel/btf/vmlinux -f tcp_v4_rcv int tcp_v4_rcv(struct sk_buff * skb); $ [acme@five ~]$ pfunct -F btf /sys/kernel/btf/vmlinux --class=sk_buff | head pskb_expand_head skb_put audit_list_rules_send netlink_ack consume_skb skb_queue_head skb_queue_tail netlink_broadcast __nlmsg_put kfree_skb [acme@five ~]$ pfunct -F btf /sys/kernel/btf/vmlinux -f audit_list_rules_send int audit_list_rules_send(struct sk_buff * request_skb, int seq); [acme@five ~]$ pfunct -F btf /sys/kernel/btf/vmlinux -f netlink_broadcast int netlink_broadcast(struct sock * ssk, struct sk_buff * skb, __u32 portid, __u32 group, gfp_t allocation); [acme@five ~]$ Seems to work :-) In a future version I'll make it work with btf and /sys/kernel/btf/vmlinux by default if only function names are provided, like pahole with types: [acme@five ~]$ pahole sk_buff_head struct sk_buff_head { struct sk_buff * next; /* 0 8 */ struct sk_buff * prev; /* 8 8 */ __u32 qlen; /* 16 4 */ spinlock_t lock; /* 20 4 */ /* size: 24, cachelines: 1, members: 4 */ /* last cacheline: 24 bytes */ }; [acme@five ~]$ pahole list_head struct list_head { struct list_head * next; /* 0 8 */ struct list_head * prev; /* 8 8 */ /* size: 16, cachelines: 1, members: 2 */ /* last cacheline: 16 bytes */ }; [acme@five ~]$ Pushed out. - Arnaldo
hi, because of gcc bug [1] we can no longer rely on DW_AT_declaration attribute to filter out declarations and end up with just one copy of the function in the BTF data. It seems this bug is not easy to fix, but regardless if the it's coming soon, it's probably good idea not to depend so much only on dwarf data and make some extra checks. Thus for function encoding we are now doing following checks: - argument names are defined for the function - there's symbol and address defined for the function - function address belongs to ftrace locations (new in v2) - function is generated only once v4 changes: - added acks - renames and change functions_valid to be local var [Andrii] - fixed error path (return err) of collect_symbols v3 changes: - added Hao's ack for patch 1 - fixed realloc memory leak [Andrii] - fixed addrs_cmp function [Andrii] - removed SET_SYMBOL macro [Andrii] - fixed the 'valid' function logic - added .init.bpf.preserve_type check - added iterator functions to new kernel section .init.bpf.preserve_type [Yonghong] v2 changes: - add check ensuring functions belong to ftrace's mcount locations, this way we ensure to have in BTF only functions available for ftrace - patch 2 changelog describes all details - use collect* function names [Andrii] - use conventional size increase in realloc [Andrii] - drop elf_sym__is_function check - drop patch 3, it's not needed, because we follow ftrace locations thanks, jirka [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97060