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authorEric W. Biederman <ebiederm@xmission.com>2018-09-25 11:27:20 +0200
committerEric W. Biederman <ebiederm@xmission.com>2018-10-03 16:47:43 +0200
commitae7795bc6187a15ec51cf258abae656a625f9980 (patch)
tree2456aa85c6b4be1ac58e272393056c0edbee038a /include/linux/signal.h
parent4cd2e0e70af6897ca2247fa1ffb1553ca16b4903 (diff)
signal: Distinguish between kernel_siginfo and siginfo
Linus recently observed that if we did not worry about the padding member in struct siginfo it is only about 48 bytes, and 48 bytes is much nicer than 128 bytes for allocating on the stack and copying around in the kernel. The obvious thing of only adding the padding when userspace is including siginfo.h won't work as there are sigframe definitions in the kernel that embed struct siginfo. So split siginfo in two; kernel_siginfo and siginfo. Keeping the traditional name for the userspace definition. While the version that is used internally to the kernel and ultimately will not be padded to 128 bytes is called kernel_siginfo. The definition of struct kernel_siginfo I have put in include/signal_types.h A set of buildtime checks has been added to verify the two structures have the same field offsets. To make it easy to verify the change kernel_siginfo retains the same size as siginfo. The reduction in size comes in a following change. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'include/linux/signal.h')
-rw-r--r--include/linux/signal.h15
1 files changed, 8 insertions, 7 deletions
diff --git a/include/linux/signal.h b/include/linux/signal.h
index de94c159bfb0..70031b10b918 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -11,18 +11,19 @@ struct task_struct;
/* for sysctl */
extern int print_fatal_signals;
-static inline void copy_siginfo(struct siginfo *to, const struct siginfo *from)
+static inline void copy_siginfo(kernel_siginfo_t *to,
+ const kernel_siginfo_t *from)
{
memcpy(to, from, sizeof(*to));
}
-static inline void clear_siginfo(struct siginfo *info)
+static inline void clear_siginfo(kernel_siginfo_t *info)
{
memset(info, 0, sizeof(*info));
}
-int copy_siginfo_to_user(struct siginfo __user *to, const struct siginfo *from);
-int copy_siginfo_from_user(struct siginfo *to, const struct siginfo __user *from);
+int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from);
+int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from);
enum siginfo_layout {
SIL_KILL,
@@ -258,11 +259,11 @@ struct pt_regs;
enum pid_type;
extern int next_signal(struct sigpending *pending, sigset_t *mask);
-extern int do_send_sig_info(int sig, struct siginfo *info,
+extern int do_send_sig_info(int sig, struct kernel_siginfo *info,
struct task_struct *p, enum pid_type type);
-extern int group_send_sig_info(int sig, struct siginfo *info,
+extern int group_send_sig_info(int sig, struct kernel_siginfo *info,
struct task_struct *p, enum pid_type type);
-extern int __group_send_sig_info(int, struct siginfo *, struct task_struct *);
+extern int __group_send_sig_info(int, struct kernel_siginfo *, struct task_struct *);
extern int sigprocmask(int, sigset_t *, sigset_t *);
extern void set_current_blocked(sigset_t *);
extern void __set_current_blocked(const sigset_t *);