Messages in this thread | | | Date | Thu, 27 Nov 2008 22:12:35 +0300 | From | Cyrill Gorcunov <> | Subject | Re: [PATCH 2/5] x86: ret_from_fork - get rid of jump back |
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[Ingo Molnar - Thu, Nov 27, 2008 at 02:41:21PM +0100] | | * Cyrill Gorcunov <gorcunov@gmail.com> wrote: | ... | | Could you test something like the patch attached below, which cleans | up this code and applies the code reduction and speedup? Warning: | completely untested! Please check that things like strace -f and gdb | attaching to forked tasks still works fine. (it should by all means) | | Thanks, | | Ingo
Ingo, I found 2.6.26 test machine where I've patched the entry_64.S in a manner you pointed. So here is a test program and strace output. Seems all works fine. Didn't check "audit" code which I simply don't know how to be done.
- Cyrill - ---
#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/types.h> #include <unistd.h>
int main(int argc, char *argv[]) { int pid;
pid = fork();
if (pid < 0) { fprintf(stderr, "Fork failed!\n"); exit(-1); }
else if (pid == 0) { printf("I am the child, return from fork=%d\n", pid); } else { printf("I am the parent, return from fork, child pid=%d\n", pid); printf("Parent exiting!\n"); exit(0); } } ---
5897 execve("./main", ["./main"], [/* 18 vars */]) = 0 5897 brk(0) = 0x2514000 5897 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fa0e517f000 5897 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) 5897 mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fa0e517d000 5897 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory) 5897 open("/etc/ld.so.cache", O_RDONLY) = 3 5897 fstat(3, {st_mode=S_IFREG|0644, st_size=48530, ...}) = 0 5897 mmap(NULL, 48530, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fa0e5171000 5897 close(3) = 0 5897 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory) 5897 open("/lib/libc.so.6", O_RDONLY) = 3 5897 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\220\345"..., 832) = 832 5897 fstat(3, {st_mode=S_IFREG|0755, st_size=1502520, ...}) = 0 5897 mmap(NULL, 3609304, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fa0e4bf0000 5897 mprotect(0x7fa0e4d59000, 2093056, PROT_NONE) = 0 5897 mmap(0x7fa0e4f58000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x168000) = 0x7fa0e4f58000 5897 mmap(0x7fa0e4f5d000, 17112, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fa0e4f5d000 5897 close(3) = 0 5897 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fa0e5170000 5897 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fa0e516f000 5897 arch_prctl(ARCH_SET_FS, 0x7fa0e516f6e0) = 0 5897 mprotect(0x7fa0e4f58000, 16384, PROT_READ) = 0 5897 mprotect(0x7fa0e5180000, 4096, PROT_READ) = 0 5897 munmap(0x7fa0e5171000, 48530) = 0 5897 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fa0e516f770) = 5898 5897 fstat(1, {st_mode=S_IFCHR|0600, st_rdev=makedev(5, 1), ...}) = 0 5898 fstat(1, <unfinished ...> 5897 ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS <unfinished ...> 5898 <... fstat resumed> {st_mode=S_IFCHR|0600, st_rdev=makedev(5, 1), ...}) = 0 5897 <... ioctl resumed> , {B38400 opost isig icanon echo ...}) = 0 5897 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 <unfinished ...> 5898 ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS <unfinished ...> 5897 <... mmap resumed> ) = 0x7fa0e517c000 5898 <... ioctl resumed> , {B38400 opost isig icanon echo ...}) = 0 5897 write(1, "I am the parent, return from for"..., 50 <unfinished ...> 5898 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 <unfinished ...> 5897 <... write resumed> ) = 50 5898 <... mmap resumed> ) = 0x7fa0e517c000 5897 write(1, "Parent exiting!\n", 16 <unfinished ...> 5898 write(1, "I am the child, return from fork"..., 35 <unfinished ...> 5897 <... write resumed> ) = 16 5898 <... write resumed> ) = 35 5897 exit_group(0) = ? 5898 exit_group(0) = ? ---
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