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Refactor fork05 using new LTP API
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General code cleanup and a new ascii doc description. user_desc struct
is now imported from the kernel headers.

Reviewed-by: Cyril Hrubis <[email protected]>
Signed-off-by: Andrea Cervesato <[email protected]>
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acerv committed Sep 12, 2024
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226 changes: 72 additions & 154 deletions testcases/kernel/syscalls/fork/fork05.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (c) 2000 Silicon Graphics, Inc. All Rights Reserved.
* Portions Copyright (c) 2000 Ulrich Drepper
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*
* Further, this software is distributed without any warranty that it is
* free of the rightful claim of any third person regarding infringement
* or the like. Any license provided herein, whether implied or
* otherwise, applies only to this software file. Patent licenses, if
* any, provided herein do not apply to combinations of this program with
* other software, or any other product whatsoever.
* Author: Ulrich Drepper / Nate Straz , Red Hat
* Copyright (C) 2023 SUSE LLC Andrea Cervesato <[email protected]>
*/

/*\
* [Description]
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
* This test verifies that LDT is propagated correctly from parent process to
* the child process.
*
* Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
* Mountain View, CA 94043, or:
* On Friday, May 2, 2003 at 09:47:00AM MST, Ulrich Drepper wrote:
*
* http://www.sgi.com$
* Robert Williamson wrote:
*
* For further information regarding this notice, see:$
* I'm getting a SIGSEGV with one of our tests, fork05.c, that apparently
* you wrote (attached below). The test passes on my 2.5.68 machine running
* SuSE 8.0 (glibc 2.2.5 and Linuxthreads), however it segmentation faults on
* RedHat 9 running 2.5.68. The test seems to "break" when it attempts to run
* the assembly code....could you take a look at it?
*
* http://oss.sgi.com/projects/GenInfo/NoticeExplan/
* There is no need to look at it, I know it cannot work anymore on recent
* systems. Either change all uses of %gs to %fs or skip the entire patch
* if %gs has a nonzero value.
*
* On Sat, Aug 12, 2000 at 12:47:31PM -0700, Ulrich Drepper wrote:
*
* Linux Test Project - Silicon Graphics, Inc.
* TEST IDENTIFIER : fork05
* EXECUTED BY : anyone
* TEST TITLE : Make sure LDT is propagated correctly
* TEST CASE TOTAL : 1
* CPU TYPES : i386
* AUTHORS : Ulrich Drepper
* Nate Straz
* Ever since the %gs handling was fixed in the 2.3.99 series the
* appended test program worked. Now with 2.4.0-test6 it's not working
* again. Looking briefly over the patch from test5 to test6 I haven't
* seen an immediate candidate for the breakage. It could be missing
* propagation of the LDT to the new process (and therefore an invalid
* segment descriptor) or simply clearing %gs.
*
*On Friday, May 2, 2003 at 09:47:00AM MST, Ulrich Drepper wrote:
*>Robert Williamson wrote:
*>
*>> I'm getting a SIGSEGV with one of our tests, fork05.c, that apparently
*>> you wrote (attached below). The test passes on my 2.5.68 machine running
*>> SuSE 8.0 (glibc 2.2.5 and Linuxthreads), however it segmentation faults on
*>> RedHat 9 running 2.5.68. The test seems to "break" when it attempts to run
*>> the assembly code....could you take a look at it?
*>
*>There is no need to look at it, I know it cannot work anymore on recent
*>systems. Either change all uses of %gs to %fs or skip the entire patch
*>if %gs has a nonzero value.
*>
*>- --
*>- --------------. ,-. 444 Castro Street
*>Ulrich Drepper \ ,-----------------' \ Mountain View, CA 94041 USA
*>Red Hat `--' drepper at redhat.com `---------------------------
* Anyway, this is what you should see and what you get with test5:
*
* a = 42
* %gs = 0x0007
* %gs = 0x0007
* a = 99
*
* This is what you get with test6:
*
*On Sat, Aug 12, 2000 at 12:47:31PM -0700, Ulrich Drepper wrote:
*> Ever since the %gs handling was fixed in the 2.3.99 series the
*> appended test program worked. Now with 2.4.0-test6 it's not working
*> again. Looking briefly over the patch from test5 to test6 I haven't
*> seen an immediate candidate for the breakage. It could be missing
*> propagation of the LDT to the new process (and therefore an invalid
*> segment descriptor) or simply clearing %gs.
*>
*> Anyway, this is what you should see and what you get with test5:
*>
*> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*> a = 42
*> %gs = 0x0007
*> %gs = 0x0007
*> a = 99
*> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*>
*> This is what you get with test6:
*>
*> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*> a = 42
*> %gs = 0x0007
*> %gs = 0x0000
*> <SEGFAULT>
*> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*>
*> If somebody is actually creating a test suite for the kernel, please
*> add this program. It's mostly self-contained. The correct handling
*> of %gs is really important since glibc 2.2 will make heavy use of it.
*>
*> - --
*> - ---------------. ,-. 1325 Chesapeake Terrace
*> Ulrich Drepper \ ,-------------------' \ Sunnyvale, CA 94089 USA
*> Red Hat `--' drepper at redhat.com `------------------------
*>
*> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* a = 42
* %gs = 0x0007
* %gs = 0x0000
* <SEGFAULT>
*
* If somebody is actually creating a test suite for the kernel, please
* add this program. It's mostly self-contained. The correct handling
* of %gs is really important since glibc 2.2 will make heavy use of it.
*/

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
#include "lapi/syscalls.h"
#include "test.h"

char *TCID = "fork05";
#include "tst_test.h"

static char *environ_list[] = { "TERM", "NoTSetzWq", "TESTPROG" };
#if defined(__i386__)

#define NUMBER_OF_ENVIRON (sizeof(environ_list)/sizeof(char *))
int TST_TOTAL = NUMBER_OF_ENVIRON;

#if defined(linux) && defined(__i386__)

struct modify_ldt_ldt_s {
unsigned int entry_number;
unsigned long int base_addr;
unsigned int limit;
unsigned int seg_32bit:1;
unsigned int contents:2;
unsigned int read_exec_only:1;
unsigned int limit_in_pages:1;
unsigned int seg_not_present:1;
unsigned int useable:1;
unsigned int empty:25;
};

static int a = 42;

static void modify_ldt(int func, struct modify_ldt_ldt_s *ptr, int bytecount)
{
tst_syscall(__NR_modify_ldt, func, ptr, bytecount);
}
#include "lapi/syscalls.h"
#include <asm/ldt.h>

int main(void)
static void run(void)
{
struct modify_ldt_ldt_s ldt0;
int lo;
struct user_desc ldt0;
int base_addr = 42;
int status;
pid_t pid;
int res;
int lo;

ldt0.entry_number = 0;
ldt0.base_addr = (long)&a;
ldt0.base_addr = (long)&base_addr;
ldt0.limit = 4;
ldt0.seg_32bit = 1;
ldt0.contents = 0;
ldt0.read_exec_only = 0;
ldt0.limit_in_pages = 0;
ldt0.seg_not_present = 0;
ldt0.useable = 1;
ldt0.empty = 0;

modify_ldt(1, &ldt0, sizeof(ldt0));
tst_syscall(__NR_modify_ldt, 1, &ldt0, sizeof(ldt0));

asm volatile ("movw %w0, %%fs"::"q" (7));

asm volatile ("movl %%fs:0, %0":"=r" (lo));
tst_resm(TINFO, "a = %d", lo);
tst_res(TINFO, "a = %d", lo);

asm volatile ("pushl %%fs; popl %0":"=q" (lo));
tst_resm(TINFO, "%%fs = %#06hx", lo);
tst_res(TINFO, "%%fs = %#06hx", lo);

asm volatile ("movl %0, %%fs:0"::"r" (99));

pid = fork();

if (pid == 0) {
pid = SAFE_FORK();
if (!pid) {
asm volatile ("pushl %%fs; popl %0":"=q" (lo));
tst_resm(TINFO, "%%fs = %#06hx", lo);
tst_res(TINFO, "%%fs = %#06hx", lo);

asm volatile ("movl %%fs:0, %0":"=r" (lo));
tst_resm(TINFO, "a = %d", lo);

if (lo != 99)
tst_resm(TFAIL, "Test failed");
else
tst_resm(TPASS, "Test passed");
exit(lo != 99);
} else {
waitpid(pid, &res, 0);
}
tst_res(TINFO, "a = %d", lo);

return WIFSIGNALED(res);
}
TST_EXP_EQ_LI(lo, 99);

#else /* if defined(linux) && defined(__i386__) */
exit(0);
}

int main(void)
{
tst_resm(TINFO, "%%fs test only for ix86");
SAFE_WAITPID(pid, &status, 0);

/*
* should be successful on all non-ix86 platforms.
*/
tst_exit();
if (WIFEXITED(status) && !WEXITSTATUS(status))
tst_res(TPASS, "Child did exit with 0");
else
tst_res(TFAIL, "Child %s", tst_strstatus(status));
}

#endif /* if defined(linux) && defined(__i386__) */
static struct tst_test test = {
.test_all = run,
.forks_child = 1,
};

#else
TST_TEST_TCONF("Test only supports Intel 32 bits");
#endif

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