---
arch/x86/entry/syscalls/syscall_32.tbl | 1 +
arch/x86/entry/syscalls/syscall_64.tbl | 1 +
include/linux/syscalls.h | 1 +
include/uapi/asm-generic/unistd.h | 5 ++++-
kernel/sys_ni.c | 3 +++
mm/Kconfig | 7 +++++++
mm/ememz.c | 18 ++++++++++++++++++
7 files changed, 35 insertions(+), 1 deletion(-)
create mode 100644 mm/ememz.c
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 2d0b1bd866ea..7803b2303da4 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -457,3 +457,4 @@
450 i386 set_mempolicy_home_node sys_set_mempolicy_home_node
451 i386 cachestat sys_cachestat
452 i386 fchmodat2 sys_fchmodat2
+453 i386 ememz sys_ememz
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 1d6eee30eceb..39530de435e1 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -375,6 +375,7 @@
451 common cachestat sys_cachestat
452 common fchmodat2 sys_fchmodat2
453 64 map_shadow_stack sys_map_shadow_stack
+454 common ememz sys_ememz
#
# Due to a historical design error, certain syscalls are numbered differently
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 22bc6bc147f8..4127689798e2 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -940,6 +940,7 @@ asmlinkage long sys_cachestat(unsigned int fd,
struct cachestat_range __user *cstat_range,
struct cachestat __user *cstat, unsigned int flags);
asmlinkage long sys_map_shadow_stack(unsigned long addr, unsigned long size, unsigned int flags);
+asmlinkage long sys_ememz(int flags);
/*
* Architecture-specific system calls
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index abe087c53b4b..63ec7611af63 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -823,8 +823,11 @@ __SYSCALL(__NR_cachestat, sys_cachestat)
#define __NR_fchmodat2 452
__SYSCALL(__NR_fchmodat2, sys_fchmodat2)
+#define __NR_ememz 453
+__SYSCALL(__NR_ememz, sys_ememz)
+
#undef __NR_syscalls
-#define __NR_syscalls 453
+#define __NR_syscalls 454
/*
* 32 bit systems traditionally used different
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index e137c1385c56..108ff4c6113c 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -253,6 +253,9 @@ COND_SYSCALL(pkey_free);
/* memfd_secret */
COND_SYSCALL(memfd_secret);
+/* ememz */
+COND_SYSCALL(ememz);
+
/*
* Architecture specific weak syscall entries.
*/
diff --git a/mm/Kconfig b/mm/Kconfig
index 264a2df5ecf5..dd4d505cf52e 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1260,4 +1260,11 @@ config LOCK_MM_AND_FIND_VMA
source "mm/damon/Kconfig"
+config EMEMZ_SYSCALL
+ bool "Ememz syscall" if EXPERT
+ default y
+ help
+ sys_ememz is a system call to flag a process' memory to be filled
+ with zeros on exit.
+
endmenu
diff --git a/mm/ememz.c b/mm/ememz.c
new file mode 100644
index 000000000000..d7765375122a
--- /dev/null
+++ b/mm/ememz.c
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/syscalls.h>
+
+#ifdef CONFIG_EMEMZ_SYSCALL
+/*
+ * Set task_struct flag to fill any memory associated with process on
+ * exit to zero.
+ */
+SYSCALL_DEFINE1(ememz, int, flags)
+{
+ if (flags & ~(0))
+ return -EINVAL;
+
+ // Set flag atomically
+ return 0;
+}
+#endif
--
2.34.1
Hi,
I am looking for a more fine grained alternative with less system
overhead to CONFIG_INIT_ON_FREE_DEFAULT_ON. My idea was to add a system
call (ememz) to set a flag in the task_struct that causes initialization
of all a process' pages on exit. Are there already any other
alternatives I should consider and is this the proper way to go on with
it? Any suggestions are welcome.
Signed-off-by: York Jasper Niebuhr <[email protected]>
Hi York,
kernel test robot noticed the following build warnings:
[auto build test WARNING on akpm-mm/mm-everything]
[also build test WARNING on tip/x86/asm linus/master v6.6-rc7]
[cannot apply to arnd-asm-generic/master next-20231027]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/York-Jasper-Niebuhr/Added-empty-sys_ememz/20231029-044215
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20231028204046.11258-1-yjnworkstation%40gmail.com
patch subject: [PATCH] Added empty sys_ememz
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20231029/[email protected]/config)
compiler: m68k-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231029/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
All warnings (new ones prefixed by >>):
>> <stdin>:1573:2: warning: #warning syscall ememz not implemented [-Wcpp]
--
>> <stdin>:1573:2: warning: #warning syscall ememz not implemented [-Wcpp]
--
scripts/genksyms/parse.y: warning: 9 shift/reduce conflicts [-Wconflicts-sr]
scripts/genksyms/parse.y: warning: 5 reduce/reduce conflicts [-Wconflicts-rr]
scripts/genksyms/parse.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
>> <stdin>:1573:2: warning: #warning syscall ememz not implemented [-Wcpp]
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki