Re: [PATCH v1 6/7] perf syscalltbl: Use lookup table containing multiple architectures

Howard Chu
2025-02-05T00:24:50Z

Hello,

On Fri, Jan 31, 2025 at 11:15 PM Ian Rogers <irogers@google.com> wrote:
>
> Switch to use the lookup table containing all architectures rather
> than tables matching the perf binary.
>
> This fixes perf trace when executed on a 32-bit i386 binary on an
> x86-64 machine. Note in the following the system call names of the
> 32-bit i386 binary as seen by an x86-64 perf.
>
> Before:
> ```
> ? ( ): a.out/447296 ... [continued]: munmap()) = 0
> 0.024 ( 0.001 ms): a.out/447296 recvfrom(ubuf: 0x2, size: 4160585708, flags: DONTROUTE|CTRUNC|TRUNC|DONTWAIT|EOR|WAITALL|FIN|SYN|CONFIRM|RST|ERRQUEUE|NOSIGNAL|WAITFORONE|BATCH|SOCK_DEVMEM|ZEROCOPY|FASTOPEN|CMSG_CLOEXEC|0x91f80000, addr: 0xe30, addr_len: 0xffce438c) = 1475198976
> 0.042 ( 0.003 ms): a.out/447296 lgetxattr(name: "", value: 0x3, size: 34) = 4160344064
> 0.054 ( 0.003 ms): a.out/447296 dup2(oldfd: -134422744, newfd: 4) = -1 ENOENT (No such file or directory)
> 0.060 ( 0.009 ms): a.out/447296 preadv(fd: 4294967196, vec: (struct iovec){.iov_base = (void *)0x2e646c2f6374652f,.iov_len = (__kernel_size_t)7307199665335594867,}, vlen: 557056, pos_h: 4160585708) = 3
> 0.074 ( 0.004 ms): a.out/447296 lgetxattr(name: "", value: 0x1, size: 2) = 4160237568
> 0.080 ( 0.001 ms): a.out/447296 lstat(filename: "", statbuf: 0x193f6) = 0
> 0.089 ( 0.007 ms): a.out/447296 preadv(fd: 4294967196, vec: (struct iovec){.iov_base = (void *)0x3833692f62696c2f,.iov_len = (__kernel_size_t)3276497845987585334,}, vlen: 557056, pos_h: 4160585708) = 3
> 0.097 ( 0.002 ms): a.out/447296 close(fd: 3</proc/447296/status>) = 512
> 0.103 ( 0.002 ms): a.out/447296 lgetxattr(name: "", value: 0x1, size: 2050) = 4157935616
> 0.107 ( 0.007 ms): a.out/447296 lgetxattr(pathname: "", name: "", value: 0x5, size: 2066) = 4158078976
> 0.116 ( 0.003 ms): a.out/447296 lgetxattr(pathname: "", name: "", value: 0x1, size: 2066) = 4159639552
> 0.121 ( 0.003 ms): a.out/447296 lgetxattr(pathname: "", name: "", value: 0x3, size: 2066) = 4160184320
> 0.129 ( 0.002 ms): a.out/447296 lgetxattr(pathname: "", name: "", value: 0x3, size: 50) = 4160196608
> 0.138 ( 0.001 ms): a.out/447296 lstat(filename: "") = 0
> 0.145 ( 0.002 ms): a.out/447296 mq_timedreceive(mqdes: 4291706800, u_msg_ptr: 0xf7f9ea48, msg_len: 134616640, u_msg_prio: 0xf7fd7fec, u_abs_timeout: (struct __kernel_timespec){.tv_sec = (__kernel_time64_t)-578174027777317696,.tv_nsec = (long long int)4160349376,}) = 0
> 0.148 ( 0.001 ms): a.out/447296 mkdirat(dfd: -134617816, pathname: " ��� ���▒���▒���", mode: IFREG|ISUID|IRUSR|IWGRP|0xf7fd0000) = 447296
> 0.150 ( 0.001 ms): a.out/447296 process_vm_writev(pid: -134617812, lvec: (struct iovec){.iov_base = (void *)0xf7f9e9c8f7f9e4c0,.iov_len = (__kernel_size_t)4160349376,}, liovcnt: 4160588048, rvec: (struct iovec){}, riovcnt: 4160585708, flags: 4291707352) = 0
> 0.197 ( 0.004 ms): a.out/447296 capget(header: 4160184320, dataptr: 8192) = 0
> 0.202 ( 0.002 ms): a.out/447296 capget(header: 1448669184, dataptr: 4096) = 0
> 0.208 ( 0.002 ms): a.out/447296 capget(header: 4160577536, dataptr: 8192) = 0
> 0.220 ( 0.001 ms): a.out/447296 getxattr(pathname: "", name: "c������", value: 0xf7f77e34, size: 1) = 0
> 0.228 ( 0.005 ms): a.out/447296 fchmod(fd: -134729728, mode: IRUGO|IWUGO|IFREG|IFIFO|ISVTX|IXUSR|0x10000) = 0
> 0.240 ( 0.009 ms): a.out/447296 preadv(fd: 4294967196, vec: 0x5658e008, pos_h: 4160192052) = 3
> 0.250 ( 0.008 ms): a.out/447296 close(fd: 3</proc/447296/status>) = 1436
> 0.260 ( 0.018 ms): a.out/447296 stat(filename: "", statbuf: 0xffce32ac) = 1436
> 0.288 (1000.213 ms): a.out/447296 readlinkat(buf: 0xffce31d4, bufsiz: 4291703244) = 0
> ```
>
> After:
> ```
> ? ( ): a.out/442930 ... [continued]: execve()) = 0
> 0.023 ( 0.002 ms): a.out/442930 brk() = 0x57760000
> 0.052 ( 0.003 ms): a.out/442930 access(filename: 0xf7f5af28, mode: R) = -1 ENOENT (No such file or directory)
> 0.059 ( 0.009 ms): a.out/442930 openat(dfd: CWD, filename: "/etc/ld.so.cache", flags: RDONLY|CLOEXEC|LARGEFILE) = 3
> 0.078 ( 0.001 ms): a.out/442930 close(fd: 3</proc/442930/status>) = 0
> 0.087 ( 0.007 ms): a.out/442930 openat(dfd: CWD, filename: "/lib/i386-linux-", flags: RDONLY|CLOEXEC|LARGEFILE) = 3
> 0.095 ( 0.002 ms): a.out/442930 read(fd: 3</proc/442930/status>, buf: 0xffbdbb70, count: 512) = 512
> 0.135 ( 0.001 ms): a.out/442930 close(fd: 3</proc/442930/status>) = 0
> 0.148 ( 0.001 ms): a.out/442930 set_tid_address(tidptr: 0xf7f2b528) = 442930 (a.out)
> 0.150 ( 0.001 ms): a.out/442930 set_robust_list(head: 0xf7f2b52c, len: 12) =
> 0.196 ( 0.004 ms): a.out/442930 mprotect(start: 0xf7f03000, len: 8192, prot: READ) = 0
> 0.202 ( 0.002 ms): a.out/442930 mprotect(start: 0x5658e000, len: 4096, prot: READ) = 0
> 0.207 ( 0.002 ms): a.out/442930 mprotect(start: 0xf7f63000, len: 8192, prot: READ) = 0
> 0.230 ( 0.005 ms): a.out/442930 munmap(addr: 0xf7f10000, len: 103414) = 0
> 0.244 ( 0.010 ms): a.out/442930 openat(dfd: CWD, filename: 0x5658d008) = 3
> 0.255 ( 0.007 ms): a.out/442930 read(fd: 3</proc/442930/status>, buf: 0xffbdb67c, count: 4096) = 1436
> 0.264 ( 0.018 ms): a.out/442930 write(fd: 1</dev/pts/4>, buf: , count: 1436) = 1436
> 0.292 (1000.173 ms): a.out/442930 clock_nanosleep(rqtp: { .tv_sec: 17866546940376776704, .tv_nsec: 4159878336 }, rmtp: 0xffbdb59c) = 0
> 1000.478 ( ): a.out/442930 exit_group() = ?
> ```
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/util/syscalltbl.c | 89 ++++++++++++++++++++++++++----------
> 1 file changed, 64 insertions(+), 25 deletions(-)
>
> diff --git a/tools/perf/util/syscalltbl.c b/tools/perf/util/syscalltbl.c
> index 760ac4d0869f..572083ba1efe 100644
> --- a/tools/perf/util/syscalltbl.c
> +++ b/tools/perf/util/syscalltbl.c
> @@ -15,16 +15,39 @@
> #include <string.h>
> #include "string2.h"
>
> -#if __BITS_PER_LONG == 64
> - #include <asm/syscalls_64.h>
> -#else
> - #include <asm/syscalls_32.h>
> -#endif
> +#include "trace/beauty/generated/syscalltbl.c"
>
> -const char *syscalltbl__name(int e_machine __maybe_unused, int id)
> +static const struct syscalltbl *find_table(int e_machine)
> {
> - if (id >= 0 && id <= (int)ARRAY_SIZE(syscall_num_to_name))
> - return syscall_num_to_name[id];
> + static const struct syscalltbl *last_table;
> + static int last_table_machine = EM_NONE;
> +
> + /* Tables only exist for EM_SPARC. */
> + if (e_machine == EM_SPARCV9)
> + e_machine = EM_SPARC;
> +
> + if (last_table_machine == e_machine && e_machine != EM_NONE)

I don't think it should be && e_machine != EM_NONE. last_table_machine
== e_machine == EM_NONE could mean last_table being uninitialized, but
what if the called *is* trying to search for e_machine == EM_NONE? Now
perf will need to traverse the whole syscalltbls array just to find
the last EM_NONE table.

My suggestion is:

static const struct syscalltbl *last_table = NULL;

and then:

if (last_table_machine == e_machine && last_table)
return last_table;

Thanks,
Howard

> + return last_table;
> +
> + for (size_t i = 0; i < ARRAY_SIZE(syscalltbls); i++) {
> + const struct syscalltbl *entry = &syscalltbls[i];
> +
> + if (entry->e_machine != e_machine && entry->e_machine != EM_NONE)
> + continue;
> +
> + last_table = entry;
> + last_table_machine = e_machine;
> + return entry;
> + }
> + return NULL;
> +}
> +
> +const char *syscalltbl__name(int e_machine, int id)
> +{
> + const struct syscalltbl *table = find_table(e_machine);
> +
> + if (table && id >= 0 && id < table->num_to_name_len)
> + return table->num_to_name[id];
> return NULL;
> }
>
> @@ -41,38 +64,54 @@ static int syscallcmpname(const void *vkey, const void *ventry)
> return strcmp(key->name, key->tbl[*entry]);
> }
>
> -int syscalltbl__id(int e_machine __maybe_unused, const char *name)
> +int syscalltbl__id(int e_machine, const char *name)
> {
> - struct syscall_cmp_key key = {
> - .name = name,
> - .tbl = syscall_num_to_name,
> - };
> - const int *id = bsearch(&key, syscall_sorted_names,
> - ARRAY_SIZE(syscall_sorted_names),
> - sizeof(syscall_sorted_names[0]),
> - syscallcmpname);
> + const struct syscalltbl *table = find_table(e_machine);
> + struct syscall_cmp_key key;
> + const int *id;
> +
> + if (!table)
> + return -1;
> +
> + key.name = name;
> + key.tbl = table->num_to_name;
> + id = bsearch(&key, table->sorted_names, table->sorted_names_len,
> + sizeof(table->sorted_names[0]), syscallcmpname);
>
> return id ? *id : -1;
> }
>
> -int syscalltbl__num_idx(int e_machine __maybe_unused)
> +int syscalltbl__num_idx(int e_machine)
> {
> - return ARRAY_SIZE(syscall_sorted_names);
> + const struct syscalltbl *table = find_table(e_machine);
> +
> + if (!table)
> + return 0;
> +
> + return table->sorted_names_len;
> }
>
> -int syscalltbl__id_at_idx(int e_machine __maybe_unused, int idx)
> +int syscalltbl__id_at_idx(int e_machine, int idx)
> {
> - return syscall_sorted_names[idx];
> + const struct syscalltbl *table = find_table(e_machine);
> +
> + if (!table)
> + return -1;
> +
> + assert(idx >= 0 && idx < table->sorted_names_len);
> + return table->sorted_names[idx];
> }
>
> -int syscalltbl__strglobmatch_next(int e_machine __maybe_unused, const char *syscall_glob, int *idx)
> +int syscalltbl__strglobmatch_next(int e_machine, const char *syscall_glob, int *idx)
> {
> - for (int i = *idx + 1; i < (int)ARRAY_SIZE(syscall_sorted_names); ++i) {
> - const char *name = syscall_num_to_name[syscall_sorted_names[i]];
> + const struct syscalltbl *table = find_table(e_machine);
> +
> + for (int i = *idx + 1; table && i < table->sorted_names_len; ++i) {
> + const char *name = table->num_to_name[table->sorted_names[i]];
>
> if (strglobmatch(name, syscall_glob)) {
> *idx = i;
> - return syscall_sorted_names[i];
> + return table->sorted_names[i];
> }
> }
>
> --
> 2.48.1.362.g079036d154-goog
>