Re: [PATCH RFC] s390x sys32 (remove duplicated code)

Re: [PATCH RFC] s390x sys32 (remove duplicated code)

[Martin Schwidefsky]

Hi Tim,

> I am working on a patch that removes the old limit of NGROUPS.
>
> In doing so, I am checking everything that references NGROUPS.  One
> such place is in arch/s390x/kernel/linux32.c.
>
> I notice these things:
> * s390x defines __kernel_old_gid_t to __kernel_gid_t (unsigned int)
> * s390x has a sys32_getgroups16() which looks JUST LIKE uid16.c
> sys_getgroups16
> * s390x does not define CONFIG_UID16, but seems to need it
The early versions of 64 bit s390x did not have the 31 bit emulation
layer. As long as only 64 bit code is executed you don't need the
16 bit uids/gids. Thats why is isn't defined.

> It seems to me that if we do:
> * s390x defines CONFIG_UID16
> * typedef __kernel_old_gid_t to u16
> * get rid of all the sys32_*16 stuff and just call the uid16.c function
I checked the code and didn't find any reason why this shouldn't work.
In fact with the 31 bit emulation layer the 64 bit kernel does need the
16 bit uid/gid system calls although only for the emulation. To make it
really perfect you could define CONFIG_UID16 dependent on
CONFIG_S390_SUPPORT. This saves a few bytes in the image if the emulation
support is not enabled.

> We could save a bit of duplicated code.  Patches that remove code are
> good, right?
Definitly.

blue skies,
   Martin

Linux/390 Design & Development, IBM Deutschland Entwicklung GmbH
Schönaicherstr. 220, D-71032 Böblingen, Telefon: 49 - (0)7031 - 16-2247
E-Mail: schwidefsky@de.ibm.com

[PATCH} s390x sys32 duplicated code cleanup (was [PATCH RFC] s390x sys32...)

[Tim Hockin]

[-- Attachment #1: Type: text/plain, Size: 1283 bytes --]

Martin Schwidefsky wrote:

>>It seems to me that if we do:
>>* s390x defines CONFIG_UID16
>>* typedef __kernel_old_gid_t to u16
>>* get rid of all the sys32_*16 stuff and just call the uid16.c function
> 
> I checked the code and didn't find any reason why this shouldn't work.
> In fact with the 31 bit emulation layer the 64 bit kernel does need the
> 16 bit uid/gid system calls although only for the emulation. To make it
> really perfect you could define CONFIG_UID16 dependent on
> CONFIG_S390_SUPPORT. This saves a few bytes in the image if the emulation
> support is not enabled.

Ok, done.  I don't know if you guys prefer BK or plain-old patch, so 
I'll do this:

Attached are the two patches (one as sent before, the other is just the 
above change).  You can apply the patches, or if you prefer, ping me 
back and I'll put a bk repository up publicly for you.  The patches are 
probably easiest.

This change will make my life easier for the rest of the ngroups crap I 
am fixing.  I will commit this locally on teh assumption it will turn up 
sooner or later on your end.

Now, for 2.5.x - do you want me to do another patchset, or are these 
close enough?

Thanks.




-- 
Tim Hockin
Systems Software Engineer
Sun Microsystems, Linux Kernel Engineering
thockin@sun.com

[-- Attachment #2: s390x-2.4.x-uid16-1.patch --]
[-- Type: text/plain, Size: 13356 bytes --]

# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
#	           ChangeSet	1.587   -> 1.588  
#	arch/s390x/defconfig	1.8     -> 1.9    
#	arch/s390x/config.in	1.9     -> 1.10   
#	arch/s390x/kernel/linux32.c	1.10    -> 1.11   
#	arch/s390x/kernel/entry.S	1.13    -> 1.14   
#	arch/s390x/kernel/wrapper32.S	1.4     -> 1.5    
#	include/asm-s390x/posix_types.h	1.1     -> 1.3    
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 02/08/26	thockin@freakshow.cobalt.com	1.588
# enable UID16 for s390x
# change s390x duplicated code to call UID16 functions
# --------------------------------------------
#
diff -Nru a/arch/s390x/config.in b/arch/s390x/config.in
--- a/arch/s390x/config.in	Wed Aug 28 17:22:31 2002
+++ b/arch/s390x/config.in	Wed Aug 28 17:22:31 2002
@@ -13,6 +13,7 @@
 mainmenu_name "Linux Kernel Configuration"
 define_bool CONFIG_ARCH_S390 y
 define_bool CONFIG_ARCH_S390X y
+define_bool CONFIG_UID16 y
 
 mainmenu_option next_comment
 comment 'Code maturity level options'
diff -Nru a/arch/s390x/defconfig b/arch/s390x/defconfig
--- a/arch/s390x/defconfig	Wed Aug 28 17:22:31 2002
+++ b/arch/s390x/defconfig	Wed Aug 28 17:22:31 2002
@@ -9,6 +9,7 @@
 # CONFIG_GENERIC_BUST_SPINLOCK is not set
 CONFIG_ARCH_S390=y
 CONFIG_ARCH_S390X=y
+CONFIG_UID16=y
 
 #
 # Code maturity level options
diff -Nru a/arch/s390x/kernel/entry.S b/arch/s390x/kernel/entry.S
--- a/arch/s390x/kernel/entry.S	Wed Aug 28 17:22:31 2002
+++ b/arch/s390x/kernel/entry.S	Wed Aug 28 17:22:31 2002
@@ -391,7 +391,7 @@
         .long  SYSCALL(sys_mount,sys32_mount_wrapper)
         .long  SYSCALL(sys_oldumount,sys32_oldumount_wrapper)
         .long  SYSCALL(sys_ni_syscall,sys32_setuid16_wrapper)   /* old setuid16 syscall*/
-        .long  SYSCALL(sys_ni_syscall,sys32_getuid16)   /* old getuid16 syscall*/
+        .long  SYSCALL(sys_ni_syscall,sys_getuid16)   /* old getuid16 syscall*/
         .long  SYSCALL(sys_ni_syscall,sys_ni_syscall) /* 25 old stime syscall */
         .long  SYSCALL(sys_ptrace,sys32_ptrace_wrapper)
         .long  SYSCALL(sys_alarm,sys32_alarm_wrapper)
@@ -413,11 +413,11 @@
         .long  SYSCALL(sys_times,sys32_times_wrapper)
         .long  SYSCALL(sys_ni_syscall,sys_ni_syscall) /* old prof syscall */
         .long  SYSCALL(sys_brk,sys32_brk_wrapper)               /* 45 */
-        .long  SYSCALL(sys_ni_syscall,sys32_setgid16)   /* old setgid16 syscall*/
-        .long  SYSCALL(sys_ni_syscall,sys32_getgid16)   /* old getgid16 syscall*/
+        .long  SYSCALL(sys_ni_syscall,sys_setgid16)   /* old setgid16 syscall*/
+        .long  SYSCALL(sys_ni_syscall,sys_getgid16)   /* old getgid16 syscall*/
         .long  SYSCALL(sys_signal,sys32_signal_wrapper)
-        .long  SYSCALL(sys_ni_syscall,sys32_geteuid16)  /* old geteuid16 syscall */
-        .long  SYSCALL(sys_ni_syscall,sys32_getegid16)  /* old getegid16 syscall */
+        .long  SYSCALL(sys_ni_syscall,sys_geteuid16)  /* old geteuid16 syscall */
+        .long  SYSCALL(sys_ni_syscall,sys_getegid16)  /* old getegid16 syscall */
         .long  SYSCALL(sys_acct,sys32_acct_wrapper)
         .long  SYSCALL(sys_umount,sys32_umount_wrapper)
         .long  SYSCALL(sys_ni_syscall,sys_ni_syscall) /* old lock syscall */
diff -Nru a/arch/s390x/kernel/linux32.c b/arch/s390x/kernel/linux32.c
--- a/arch/s390x/kernel/linux32.c	Wed Aug 28 17:22:31 2002
+++ b/arch/s390x/kernel/linux32.c	Wed Aug 28 17:22:31 2002
@@ -66,181 +66,6 @@
 
 #include "linux32.h"
 
-extern asmlinkage long sys_chown(const char *, uid_t,gid_t);
-extern asmlinkage long sys_lchown(const char *, uid_t,gid_t);
-extern asmlinkage long sys_fchown(unsigned int, uid_t,gid_t);
-extern asmlinkage long sys_setregid(gid_t, gid_t);
-extern asmlinkage long sys_setgid(gid_t);
-extern asmlinkage long sys_setreuid(uid_t, uid_t);
-extern asmlinkage long sys_setuid(uid_t);
-extern asmlinkage long sys_setresuid(uid_t, uid_t, uid_t);
-extern asmlinkage long sys_setresgid(gid_t, gid_t, gid_t);
-extern asmlinkage long sys_setfsuid(uid_t);
-extern asmlinkage long sys_setfsgid(gid_t);
- 
-/* For this source file, we want overflow handling. */
-
-#undef high2lowuid
-#undef high2lowgid
-#undef low2highuid
-#undef low2highgid
-#undef SET_UID16
-#undef SET_GID16
-#undef NEW_TO_OLD_UID
-#undef NEW_TO_OLD_GID
-#undef SET_OLDSTAT_UID
-#undef SET_OLDSTAT_GID
-#undef SET_STAT_UID
-#undef SET_STAT_GID
-
-#define high2lowuid(uid) ((uid) > 65535) ? (u16)overflowuid : (u16)(uid)
-#define high2lowgid(gid) ((gid) > 65535) ? (u16)overflowgid : (u16)(gid)
-#define low2highuid(uid) ((uid) == (u16)-1) ? (uid_t)-1 : (uid_t)(uid)
-#define low2highgid(gid) ((gid) == (u16)-1) ? (gid_t)-1 : (gid_t)(gid)
-#define SET_UID16(var, uid)	var = high2lowuid(uid)
-#define SET_GID16(var, gid)	var = high2lowgid(gid)
-#define NEW_TO_OLD_UID(uid)	high2lowuid(uid)
-#define NEW_TO_OLD_GID(gid)	high2lowgid(gid)
-#define SET_OLDSTAT_UID(stat, uid)	(stat).st_uid = high2lowuid(uid)
-#define SET_OLDSTAT_GID(stat, gid)	(stat).st_gid = high2lowgid(gid)
-#define SET_STAT_UID(stat, uid)		(stat).st_uid = high2lowuid(uid)
-#define SET_STAT_GID(stat, gid)		(stat).st_gid = high2lowgid(gid)
-
-asmlinkage long sys32_chown16(const char * filename, u16 user, u16 group)
-{
-	return sys_chown(filename, low2highuid(user), low2highgid(group));
-}
-
-asmlinkage long sys32_lchown16(const char * filename, u16 user, u16 group)
-{
-	return sys_lchown(filename, low2highuid(user), low2highgid(group));
-}
-
-asmlinkage long sys32_fchown16(unsigned int fd, u16 user, u16 group)
-{
-	return sys_fchown(fd, low2highuid(user), low2highgid(group));
-}
-
-asmlinkage long sys32_setregid16(u16 rgid, u16 egid)
-{
-	return sys_setregid(low2highgid(rgid), low2highgid(egid));
-}
-
-asmlinkage long sys32_setgid16(u16 gid)
-{
-	return sys_setgid((gid_t)gid);
-}
-
-asmlinkage long sys32_setreuid16(u16 ruid, u16 euid)
-{
-	return sys_setreuid(low2highuid(ruid), low2highuid(euid));
-}
-
-asmlinkage long sys32_setuid16(u16 uid)
-{
-	return sys_setuid((uid_t)uid);
-}
-
-asmlinkage long sys32_setresuid16(u16 ruid, u16 euid, u16 suid)
-{
-	return sys_setresuid(low2highuid(ruid), low2highuid(euid),
-		low2highuid(suid));
-}
-
-asmlinkage long sys32_getresuid16(u16 *ruid, u16 *euid, u16 *suid)
-{
-	int retval;
-
-	if (!(retval = put_user(high2lowuid(current->uid), ruid)) &&
-	    !(retval = put_user(high2lowuid(current->euid), euid)))
-		retval = put_user(high2lowuid(current->suid), suid);
-
-	return retval;
-}
-
-asmlinkage long sys32_setresgid16(u16 rgid, u16 egid, u16 sgid)
-{
-	return sys_setresgid(low2highgid(rgid), low2highgid(egid),
-		low2highgid(sgid));
-}
-
-asmlinkage long sys32_getresgid16(u16 *rgid, u16 *egid, u16 *sgid)
-{
-	int retval;
-
-	if (!(retval = put_user(high2lowgid(current->gid), rgid)) &&
-	    !(retval = put_user(high2lowgid(current->egid), egid)))
-		retval = put_user(high2lowgid(current->sgid), sgid);
-
-	return retval;
-}
-
-asmlinkage long sys32_setfsuid16(u16 uid)
-{
-	return sys_setfsuid((uid_t)uid);
-}
-
-asmlinkage long sys32_setfsgid16(u16 gid)
-{
-	return sys_setfsgid((gid_t)gid);
-}
-
-asmlinkage long sys32_getgroups16(int gidsetsize, u16 *grouplist)
-{
-	u16 groups[NGROUPS];
-	int i,j;
-
-	if (gidsetsize < 0)
-		return -EINVAL;
-	i = current->ngroups;
-	if (gidsetsize) {
-		if (i > gidsetsize)
-			return -EINVAL;
-		for(j=0;j<i;j++)
-			groups[j] = current->groups[j];
-		if (copy_to_user(grouplist, groups, sizeof(u16)*i))
-			return -EFAULT;
-	}
-	return i;
-}
-
-asmlinkage long sys32_setgroups16(int gidsetsize, u16 *grouplist)
-{
-	u16 groups[NGROUPS];
-	int i;
-
-	if (!capable(CAP_SETGID))
-		return -EPERM;
-	if ((unsigned) gidsetsize > NGROUPS)
-		return -EINVAL;
-	if (copy_from_user(groups, grouplist, gidsetsize * sizeof(u16)))
-		return -EFAULT;
-	for (i = 0 ; i < gidsetsize ; i++)
-		current->groups[i] = (gid_t)groups[i];
-	current->ngroups = gidsetsize;
-	return 0;
-}
-
-asmlinkage long sys32_getuid16(void)
-{
-	return high2lowuid(current->uid);
-}
-
-asmlinkage long sys32_geteuid16(void)
-{
-	return high2lowuid(current->euid);
-}
-
-asmlinkage long sys32_getgid16(void)
-{
-	return high2lowgid(current->gid);
-}
-
-asmlinkage long sys32_getegid16(void)
-{
-	return high2lowgid(current->egid);
-}
-
 /* 32-bit timeval and related flotsam.  */
 
 struct timeval32
diff -Nru a/arch/s390x/kernel/wrapper32.S b/arch/s390x/kernel/wrapper32.S
--- a/arch/s390x/kernel/wrapper32.S	Wed Aug 28 17:22:31 2002
+++ b/arch/s390x/kernel/wrapper32.S	Wed Aug 28 17:22:31 2002
@@ -83,7 +83,7 @@
 	llgtr	%r2,%r2			# const char *
 	llgfr	%r3,%r3			# __kernel_old_uid_emu31_t 
 	llgfr	%r4,%r4			# __kernel_old_uid_emu31_t 
-	jg	sys32_lchown16		# branch to system call
+	jg	sys_lchown16		# branch to system call
 
 	.globl  sys32_lseek_wrapper 
 sys32_lseek_wrapper:
@@ -111,7 +111,7 @@
 	.globl  sys32_setuid16_wrapper 
 sys32_setuid16_wrapper:
 	llgfr	%r2,%r2			# __kernel_old_uid_emu31_t 
-	jg	sys32_setuid16		# branch to system call
+	jg	sys_setuid16		# branch to system call
 
 #sys32_getuid16_wrapper			# void 
 
@@ -195,7 +195,7 @@
 	.globl  sys32_setgid16_wrapper 
 sys32_setgid16_wrapper:
 	llgfr	%r2,%r2			# __kernel_old_gid_emu31_t 
-	jg	sys32_setgid16		# branch to system call
+	jg	sys_setgid16		# branch to system call
 
 #sys32_getgid16_wrapper			# void 
 
@@ -278,13 +278,13 @@
 sys32_setreuid16_wrapper:
 	llgfr	%r2,%r2			# __kernel_old_uid_emu31_t 
 	llgfr	%r3,%r3			# __kernel_old_uid_emu31_t 
-	jg	sys32_setreuid16	# branch to system call
+	jg	sys_setreuid16		# branch to system call
 
 	.globl  sys32_setregid16_wrapper 
 sys32_setregid16_wrapper:
 	llgfr	%r2,%r2			# __kernel_old_gid_emu31_t 
 	llgfr	%r3,%r3			# __kernel_old_gid_emu31_t 
-	jg	sys32_setregid16	# branch to system call
+	jg	sys_setregid16		# branch to system call
 
 #sys32_sigsuspend_wrapper		# done in sigsuspend_glue 
 
@@ -338,13 +338,13 @@
 sys32_getgroups16_wrapper:
 	lgfr	%r2,%r2			# int
 	llgtr	%r3,%r3			# __kernel_old_gid_emu31_t *
-	jg	sys32_getgroups16	# branch to system call
+	jg	sys_getgroups16		# branch to system call
 
 	.globl  sys32_setgroups16_wrapper 
 sys32_setgroups16_wrapper:
 	lgfr	%r2,%r2			# int
 	llgtr	%r3,%r3			# __kernel_old_gid_emu31_t *
-	jg	sys32_setgroups16	# branch to system call
+	jg	sys_setgroups16		# branch to system call
 
 	.globl  sys32_symlink_wrapper 
 sys32_symlink_wrapper:
@@ -419,7 +419,7 @@
 	llgfr	%r2,%r2			# unsigned int
 	llgtr	%r3,%r3			# __kernel_old_uid_emu31_t *
 	llgtr	%r4,%r4			# __kernel_old_gid_emu31_t *
-	jg	sys32_fchown16		# branch to system call
+	jg	sys_fchown16		# branch to system call
 
 	.globl  sys32_getpriority_wrapper 
 sys32_getpriority_wrapper:
@@ -619,12 +619,12 @@
 	.globl  sys32_setfsuid16_wrapper 
 sys32_setfsuid16_wrapper:
 	llgfr	%r2,%r2			# __kernel_old_uid_emu31_t 
-	jg	sys32_setfsuid16	# branch to system call
+	jg	sys_setfsuid16		# branch to system call
 
 	.globl  sys32_setfsgid16_wrapper 
 sys32_setfsgid16_wrapper:
 	llgfr	%r2,%r2			# __kernel_old_gid_emu31_t 
-	jg	sys32_setfsgid16	# branch to system call
+	jg	sys_setfsgid16		# branch to system call
 
 	.globl  sys32_llseek_wrapper 
 sys32_llseek_wrapper:
@@ -771,14 +771,14 @@
 	llgfr	%r2,%r2			# __kernel_old_uid_emu31_t 
 	llgfr	%r3,%r3			# __kernel_old_uid_emu31_t 
 	llgfr	%r4,%r4			# __kernel_old_uid_emu31_t 
-	jg	sys32_setresuid16	# branch to system call
+	jg	sys_setresuid16		# branch to system call
 
 	.globl  sys32_getresuid16_wrapper 
 sys32_getresuid16_wrapper:
 	llgtr	%r2,%r2			# __kernel_old_uid_emu31_t *
 	llgtr	%r3,%r3			# __kernel_old_uid_emu31_t *
 	llgtr	%r4,%r4			# __kernel_old_uid_emu31_t *
-	jg	sys32_getresuid16	# branch to system call
+	jg	sys_getresuid16		# branch to system call
 
 	.globl  sys32_query_module_wrapper 
 sys32_query_module_wrapper:
@@ -808,14 +808,14 @@
 	llgfr	%r2,%r2			# __kernel_old_gid_emu31_t 
 	llgfr	%r3,%r3			# __kernel_old_gid_emu31_t 
 	llgfr	%r4,%r4			# __kernel_old_gid_emu31_t 
-	jg	sys32_setresgid16	# branch to system call
+	jg	sys_setresgid16		# branch to system call
 
 	.globl  sys32_getresgid16_wrapper 
 sys32_getresgid16_wrapper:
 	llgtr	%r2,%r2			# __kernel_old_gid_emu31_t *
 	llgtr	%r3,%r3			# __kernel_old_gid_emu31_t *
 	llgtr	%r4,%r4			# __kernel_old_gid_emu31_t *
-	jg	sys32_getresgid16	# branch to system call
+	jg	sys_getresgid16		# branch to system call
 
 	.globl  sys32_prctl_wrapper 
 sys32_prctl_wrapper:
@@ -889,7 +889,7 @@
 	llgtr	%r2,%r2			# const char *
 	llgfr	%r3,%r3			# __kernel_old_uid_emu31_t 
 	llgfr	%r4,%r4			# __kernel_old_gid_emu31_t 
-	jg	sys32_chown16		# branch to system call
+	jg	sys_chown16		# branch to system call
 
 	.globl  sys32_getcwd_wrapper 
 sys32_getcwd_wrapper:
diff -Nru a/include/asm-s390x/posix_types.h b/include/asm-s390x/posix_types.h
--- a/include/asm-s390x/posix_types.h	Wed Aug 28 17:22:31 2002
+++ b/include/asm-s390x/posix_types.h	Wed Aug 28 17:22:31 2002
@@ -37,8 +37,8 @@
 typedef unsigned short	__kernel_uid16_t;
 typedef unsigned short	__kernel_gid16_t;
 
-typedef __kernel_uid_t __kernel_old_uid_t;
-typedef __kernel_gid_t __kernel_old_gid_t;
+typedef __kernel_uid16_t __kernel_old_uid_t;
+typedef __kernel_gid16_t __kernel_old_gid_t;
 typedef __kernel_uid_t __kernel_uid32_t;
 typedef __kernel_gid_t __kernel_gid32_t;
 

[-- Attachment #3: s390x-2.4.x-uid16-2.patch --]
[-- Type: text/plain, Size: 1697 bytes --]

# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
#	           ChangeSet	1.588   -> 1.589  
#	arch/s390x/defconfig	1.9     -> 1.10   
#	arch/s390x/config.in	1.10    -> 1.11   
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 02/08/28	thockin@freakshow.cobalt.com	1.589
# S390x: make CONFIG_UID16 depend on legacy CONFIG_S390_SUPPORT
# --------------------------------------------
#
diff -Nru a/arch/s390x/config.in b/arch/s390x/config.in
--- a/arch/s390x/config.in	Wed Aug 28 17:22:30 2002
+++ b/arch/s390x/config.in	Wed Aug 28 17:22:30 2002
@@ -13,7 +13,6 @@
 mainmenu_name "Linux Kernel Configuration"
 define_bool CONFIG_ARCH_S390 y
 define_bool CONFIG_ARCH_S390X y
-define_bool CONFIG_UID16 y
 
 mainmenu_option next_comment
 comment 'Code maturity level options'
@@ -25,6 +24,7 @@
 bool 'Symmetric multi-processing support' CONFIG_SMP
 bool 'Kernel support for 31 bit emulation' CONFIG_S390_SUPPORT
 if [ "$CONFIG_S390_SUPPORT" = "y" ]; then
+  define_bool CONFIG_UID16 y
   tristate 'Kernel support for 31 bit ELF binaries' CONFIG_BINFMT_ELF32 
 fi
 endmenu
diff -Nru a/arch/s390x/defconfig b/arch/s390x/defconfig
--- a/arch/s390x/defconfig	Wed Aug 28 17:22:30 2002
+++ b/arch/s390x/defconfig	Wed Aug 28 17:22:30 2002
@@ -9,7 +9,6 @@
 # CONFIG_GENERIC_BUST_SPINLOCK is not set
 CONFIG_ARCH_S390=y
 CONFIG_ARCH_S390X=y
-CONFIG_UID16=y
 
 #
 # Code maturity level options
@@ -21,6 +20,7 @@
 #
 CONFIG_SMP=y
 CONFIG_S390_SUPPORT=y
+CONFIG_UID16=y
 CONFIG_BINFMT_ELF32=y
 
 #

Re: [PATCH} s390x sys32 duplicated code cleanup (was [PATCH RFC] s390x sys32...)

[Tim Hockin]

Tim Hockin wrote:
> Martin Schwidefsky wrote:
> 
>>> It seems to me that if we do:
>>> * s390x defines CONFIG_UID16
>>> * typedef __kernel_old_gid_t to u16
>>> * get rid of all the sys32_*16 stuff and just call the uid16.c function
>>
>>
>> I checked the code and didn't find any reason why this shouldn't work.
>> In fact with the 31 bit emulation layer the 64 bit kernel does need the
>> 16 bit uid/gid system calls although only for the emulation. To make it
>> really perfect you could define CONFIG_UID16 dependent on
>> CONFIG_S390_SUPPORT. This saves a few bytes in the image if the emulation
>> support is not enabled.

Uggh, DaveM pointed out a very good issue with this fix (similar for 
Sparc64) and core files.  Core files will now have truncated uid/gid 
values because fs/binfmt_elf calls NEW_TO_OLD_UID().  May be other 
places, too.

I guess you should not apply this patch until I've had a better think 
about it.

Tim




-- 
Tim Hockin
Systems Software Engineer
Sun Microsystems, Linux Kernel Engineering
thockin@sun.com

Re: [PATCH} s390x sys32 duplicated code cleanup (was [PATCH RFC] s390x sys32...)

[Martin Schwidefsky]

Hi Tim,

>Uggh, DaveM pointed out a very good issue with this fix (similar for
>Sparc64) and core files.  Core files will now have truncated uid/gid
>values because fs/binfmt_elf calls NEW_TO_OLD_UID().  May be other
>places, too.
>
>I guess you should not apply this patch until I've had a better think
>about it.

Sad but true. And I don't see an easy way around it without changes
to fs/binfmt_elf.c.

blue skies,
   Martin

Linux/390 Design & Development, IBM Deutschland Entwicklung GmbH
Schönaicherstr. 220, D-71032 Böblingen, Telefon: 49 - (0)7031 - 16-2247
E-Mail: schwidefsky@de.ibm.com