From 7e40f2ab0a7e36706ee78b78b3792f08f208cd44 Mon Sep 17 00:00:00 2001 From: Balbir Singh Date: Mon, 23 Apr 2007 14:41:05 -0700 Subject: [PATCH] Taskstats fix the structure members alignment issue We broke the the alignment of members of taskstats to the 8 byte boundary with the CSA patches. In the current kernel, the taskstats structure is not suitable for use by 32 bit applications in a 64 bit kernel. On x86_64 Offsets of taskstats' members (64 bit kernel, 64 bit application) @taskstats'offsetof[@taskstats'indices] = ( 0, # version 4, # ac_exitcode 8, # ac_flag 9, # ac_nice 16, # cpu_count 24, # cpu_delay_total 32, # blkio_count 40, # blkio_delay_total 48, # swapin_count 56, # swapin_delay_total 64, # cpu_run_real_total 72, # cpu_run_virtual_total 80, # ac_comm 112, # ac_sched 113, # ac_pad 116, # ac_uid 120, # ac_gid 124, # ac_pid 128, # ac_ppid 132, # ac_btime 136, # ac_etime 144, # ac_utime 152, # ac_stime 160, # ac_minflt 168, # ac_majflt 176, # coremem 184, # virtmem 192, # hiwater_rss 200, # hiwater_vm 208, # read_char 216, # write_char 224, # read_syscalls 232, # write_syscalls 240, # read_bytes 248, # write_bytes 256, # cancelled_write_bytes ); Offsets of taskstats' members (64 bit kernel, 32 bit application) @taskstats'offsetof[@taskstats'indices] = ( 0, # version 4, # ac_exitcode 8, # ac_flag 9, # ac_nice 12, # cpu_count 20, # cpu_delay_total 28, # blkio_count 36, # blkio_delay_total 44, # swapin_count 52, # swapin_delay_total 60, # cpu_run_real_total 68, # cpu_run_virtual_total 76, # ac_comm 108, # ac_sched 109, # ac_pad 112, # ac_uid 116, # ac_gid 120, # ac_pid 124, # ac_ppid 128, # ac_btime 132, # ac_etime 140, # ac_utime 148, # ac_stime 156, # ac_minflt 164, # ac_majflt 172, # coremem 180, # virtmem 188, # hiwater_rss 196, # hiwater_vm 204, # read_char 212, # write_char 220, # read_syscalls 228, # write_syscalls 236, # read_bytes 244, # write_bytes 252, # cancelled_write_bytes ); This is one way to solve the problem without re-arranging structure members is to pack the structure. The patch adds an __attribute__((aligned(8))) to the taskstats structure members so that 32 bit applications using taskstats can work with a 64 bit kernel. Using __attribute__((packed)) would break the 64 bit alignment of members. The fix was tested on x86_64. After the fix, we got Offsets of taskstats' members (64 bit kernel, 64 bit application) @taskstats'offsetof[@taskstats'indices] = ( 0, # version 4, # ac_exitcode 8, # ac_flag 9, # ac_nice 16, # cpu_count 24, # cpu_delay_total 32, # blkio_count 40, # blkio_delay_total 48, # swapin_count 56, # swapin_delay_total 64, # cpu_run_real_total 72, # cpu_run_virtual_total 80, # ac_comm 112, # ac_sched 113, # ac_pad 120, # ac_uid 124, # ac_gid 128, # ac_pid 132, # ac_ppid 136, # ac_btime 144, # ac_etime 152, # ac_utime 160, # ac_stime 168, # ac_minflt 176, # ac_majflt 184, # coremem 192, # virtmem 200, # hiwater_rss 208, # hiwater_vm 216, # read_char 224, # write_char 232, # read_syscalls 240, # write_syscalls 248, # read_bytes 256, # write_bytes 264, # cancelled_write_bytes ); Offsets of taskstats' members (64 bit kernel, 32 bit application) @taskstats'offsetof[@taskstats'indices] = ( 0, # version 4, # ac_exitcode 8, # ac_flag 9, # ac_nice 16, # cpu_count 24, # cpu_delay_total 32, # blkio_count 40, # blkio_delay_total 48, # swapin_count 56, # swapin_delay_total 64, # cpu_run_real_total 72, # cpu_run_virtual_total 80, # ac_comm 112, # ac_sched 113, # ac_pad 120, # ac_uid 124, # ac_gid 128, # ac_pid 132, # ac_ppid 136, # ac_btime 144, # ac_etime 152, # ac_utime 160, # ac_stime 168, # ac_minflt 176, # ac_majflt 184, # coremem 192, # virtmem 200, # hiwater_rss 208, # hiwater_vm 216, # read_char 224, # write_char 232, # read_syscalls 240, # write_syscalls 248, # read_bytes 256, # write_bytes 264, # cancelled_write_bytes ); Signed-off-by: Balbir Singh Cc: Jay Lan Cc: Shailabh Nagar Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/taskstats.h | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/include/linux/taskstats.h b/include/linux/taskstats.h index 3fced4798255..a46104a28f66 100644 --- a/include/linux/taskstats.h +++ b/include/linux/taskstats.h @@ -31,7 +31,7 @@ */ -#define TASKSTATS_VERSION 3 +#define TASKSTATS_VERSION 4 #define TS_COMM_LEN 32 /* should be >= TASK_COMM_LEN * in linux/sched.h */ @@ -66,7 +66,7 @@ struct taskstats { /* Delay waiting for cpu, while runnable * count, delay_total NOT updated atomically */ - __u64 cpu_count; + __u64 cpu_count __attribute__((aligned(8))); __u64 cpu_delay_total; /* Following four fields atomically updated using task->delays->lock */ @@ -101,14 +101,17 @@ struct taskstats { /* Basic Accounting Fields start */ char ac_comm[TS_COMM_LEN]; /* Command name */ - __u8 ac_sched; /* Scheduling discipline */ + __u8 ac_sched __attribute__((aligned(8))); + /* Scheduling discipline */ __u8 ac_pad[3]; - __u32 ac_uid; /* User ID */ + __u32 ac_uid __attribute__((aligned(8))); + /* User ID */ __u32 ac_gid; /* Group ID */ __u32 ac_pid; /* Process ID */ __u32 ac_ppid; /* Parent process ID */ __u32 ac_btime; /* Begin time [sec since 1970] */ - __u64 ac_etime; /* Elapsed time [usec] */ + __u64 ac_etime __attribute__((aligned(8))); + /* Elapsed time [usec] */ __u64 ac_utime; /* User CPU time [usec] */ __u64 ac_stime; /* SYstem CPU time [usec] */ __u64 ac_minflt; /* Minor Page Fault Count */ -- 2.20.1