@samitouri / QOSamiQemu / commits / 6e0aa9f6c7

linux-user/strace: add fsmount series of syscalls

Following the addition of fsmount(2) series of syscalls in the syscall handler, strace support is added, with a dedicated function to print the parameters of fsconfig(2), which contains parameters that can be interpreted as multiple types. Snippet of the strace dump when running `mount -t tmpfs tmpfs /media`: 18 fsopen(tmpfs,1) = 3 18 read(3,0x407fcf1c,8191) = -1 errno=61 (No data available) 18 fsconfig(3,FSCONFIG_SET_STRING,"source","tmpfs",0) = 0 18 read(3,0x407fce3c,8191) = -1 errno=61 (No data available) 18 fsconfig(3,FSCONFIG_CMD_CREATE,NULL,NULL,0) = 0 18 read(3,0x407fce3c,8191) = -1 errno=61 (No data available) 18 fsmount(3,1,0) = 4 18 read(3,0x407fce3c,8191) = -1 errno=61 (No data available) 18 statx(4,"",AT_EMPTY_PATH|AT_STATX_SYNC_AS_STAT,0x1000,0x407fee98) = 0 18 move_mount(4,,-100,/media,4) = 0 18 read(3,0x407fcfcc,8191) = -1 errno=61 (No data available) 18 close(3) = 0 18 close(4) = 0 v2: Fixed build on RHEL9 due to missing syscalls (Helge) Signed-off-by: Xinhui Yang <cyan@cyano.uk> Reviewed-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com> Signed-off-by: Helge Deller <deller@gmx.de>

Xinhui Yang committed May 29, 2026 at 14:53 UTC 6e0aa9f6c731df3f8d1071cfd5ec63fe7b923713
2 files changed +120
linux-user/strace.c
+105
@@ -4344,6 +4344,111 @@ print_statx(CPUArchState *cpu_env, const struct syscallname *name,
4344 }
4345 #endif
4346
4347 +#if defined(TARGET_NR_fsconfig) && defined(NR_fsconfig)
4348 +static void
4349 +print_fsconfig_cmd_name(int cmd)
4350 +{
4351 + switch (cmd) {
4352 + case FSCONFIG_SET_FLAG:
4353 + qemu_log("%s%s", "FSCONFIG_SET_FLAG", get_comma(0));
4354 + break;
4355 + case FSCONFIG_SET_STRING:
4356 + qemu_log("%s%s", "FSCONFIG_SET_STRING", get_comma(0));
4357 + break;
4358 + case FSCONFIG_SET_BINARY:
4359 + qemu_log("%s%s", "FSCONFIG_SET_BINARY", get_comma(0));
4360 + break;
4361 + case FSCONFIG_SET_PATH:
4362 + qemu_log("%s%s", "FSCONFIG_SET_PATH", get_comma(0));
4363 + break;
4364 + case FSCONFIG_SET_PATH_EMPTY:
4365 + qemu_log("%s%s", "FSCONFIG_SET_PATH_EMPTY", get_comma(0));
4366 + break;
4367 + case FSCONFIG_SET_FD:
4368 + qemu_log("%s%s", "FSCONFIG_SET_FD", get_comma(0));
4369 + break;
4370 + case FSCONFIG_CMD_CREATE:
4371 + qemu_log("%s%s", "FSCONFIG_CMD_CREATE", get_comma(0));
4372 + break;
4373 + case FSCONFIG_CMD_RECONFIGURE:
4374 + qemu_log("%s%s", "FSCONFIG_CMD_RECONFIGURE", get_comma(0));
4375 + break;
4376 +#ifdef FSCONFIG_CMD_CREATE_EXCL
4377 + case FSCONFIG_CMD_CREATE_EXCL:
4378 + /* Only available since Linux 6.6. */
4379 + qemu_log("%s%s", "FSCONFIG_CMD_CREATE_EXCL", get_comma(0));
4380 + break;
4381 +#endif
4382 + default:
4383 + qemu_log("%s (%d)%s", "UNKNOWN_CMD", cmd, get_comma(0));
4384 + break;
4385 + }
4386 +}
4387 +
4388 +static void
4389 +print_fsconfig(CPUArchState *cpu_env, const struct syscallname *name,
4390 + abi_long arg0, abi_long arg1, abi_long arg2,
4391 + abi_long arg3, abi_long arg4, abi_long arg5)
4392 +{
4393 + /*
4394 + * fsconfig(int fd, int cmd, char* key, void* value, int aux)
4395 + * Where:
4396 + * fd: file descriptor returned by fsopen().
4397 + * cmd: integer constant specifying a command.
4398 + * key: a string, can be NULL on certain commands.
4399 + * value: any data in a buffer, can be NULL, raw buffer or a string.
4400 + * aux: axillary values such as flags for FSCONFIG_SET_PATH.
4401 + */
4402 + int cmd = (int) arg1;
4403 + print_syscall_prologue(name);
4404 + print_raw_param("%d", arg0, 0);
4405 + print_fsconfig_cmd_name(cmd);
4406 + /* Process arg2 (key). */
4407 + switch (cmd) {
4408 + case FSCONFIG_SET_FLAG:
4409 + case FSCONFIG_SET_STRING:
4410 + case FSCONFIG_SET_BINARY:
4411 + case FSCONFIG_SET_PATH:
4412 + case FSCONFIG_SET_PATH_EMPTY:
4413 + case FSCONFIG_SET_FD:
4414 + print_string(arg2, 0);
4415 + break;
4416 + default:
4417 + print_pointer(arg2, 0);
4418 + break;
4419 + }
4420 + /* Process arg3 (value). */
4421 + switch (cmd) {
4422 + case FSCONFIG_SET_STRING:
4423 + case FSCONFIG_SET_PATH:
4424 + case FSCONFIG_SET_PATH_EMPTY:
4425 + print_string(arg3, 0);
4426 + break;
4427 + default:
4428 + print_pointer(arg3, 0);
4429 + break;
4430 + }
4431 + /*
4432 + * Process arg4 (aux).
4433 + * On FSCONFIG_SET_PATH and FSCONFIG_SET_PATH_EMPTY, aux can
4434 + * be either 0 or AT_FDCWD.
4435 + * On FSCONFIG_SET_BINARY, aux is an integer to state the length
4436 + * of the buffer pointed by arg3.
4437 + * Otherwise, it must be 0.
4438 + */
4439 + switch (cmd) {
4440 + case FSCONFIG_SET_PATH:
4441 + case FSCONFIG_SET_PATH_EMPTY:
4442 + print_at_dirfd(arg4, 1);
4443 + break;
4444 + default:
4445 + print_raw_param("%d", arg4, 1);
4446 + break;
4447 + }
4448 + print_syscall_epilogue(name);
4449 +}
4450 +#endif
4451 +
4452 #ifdef TARGET_NR_ioctl
4453 static void
4454 print_ioctl(CPUArchState *cpu_env, const struct syscallname *name,
linux-user/strace.list
+15
@@ -1722,3 +1722,18 @@
1722 #ifdef TARGET_NR_rseq
1723 { TARGET_NR_rseq, "rseq" , "%s(%p,%u,%d,%#x)", NULL, NULL },
1724 #endif
1725 +#ifdef TARGET_NR_fsopen
1726 +{ TARGET_NR_fsopen, "fsopen", "%s(%s,%d)", NULL, NULL },
1727 +#endif
1728 +#if defined(TARGET_NR_fsconfig) && defined(NR_fsconfig)
1729 +{ TARGET_NR_fsconfig, "fsconfig", NULL, print_fsconfig, NULL },
1730 +#endif
1731 +#ifdef TARGET_NR_fsmount
1732 +{ TARGET_NR_fsmount, "fsmount", "%s(%d,%d,%d)", NULL, NULL },
1733 +#endif
1734 +#ifdef TARGET_NR_move_mount
1735 +{ TARGET_NR_move_mount, "move_mount", "%s(%d,%s,%d,%s,%d)", NULL, NULL },
1736 +#endif
1737 +#ifdef TARGET_NR_fspick
1738 +{ TARGET_NR_fspick, "fspick", "%s(%d,%s,%d)", NULL, NULL },
1739 +#endif