ia64: optimize syscallent table

Use shuffle_scno since all valid syscall numbers start from 1024.

* linux/syscallent_base_nr.h: New file.
* linux/ia64/syscallent_base_nr.h: Likewise.
* linux/ia64/shuffle_scno.c: Likewise.
* Makefile.am (EXTRA_DIST): Add them.
* linux/ia64/syscallent.h [SYSCALLENT_BASE_NR] (BASE_NR): Define to 0.
* syscall.c: Include "syscallent_base_nr.h".
* clone.c [IA64] (ARG_STACKSIZE, ARG_PTID, ARG_CTID, ARG_TLS): Use
shuffle_scno.

Co-Authored-by: Dmitry V. Levin <ldv@altlinux.org>

diff --git a/Makefile.am b/Makefile.am
index 628e7e907137b7433c866abdc9edf495e9dfb374..dfd798921cc399e800832f9d871fa4345c2fb13b 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -588,7 +588,9 @@ EXTRA_DIST =                                \
        linux/ia64/rt_sigframe.h        \
        linux/ia64/set_error.c          \
        linux/ia64/set_scno.c           \
+       linux/ia64/shuffle_scno.c       \
        linux/ia64/syscallent.h         \
+       linux/ia64/syscallent_base_nr.h \
        linux/ia64/userent.h            \
        linux/inet_diag.h               \
        linux/m68k/arch_defs_.h         \
@@ -849,6 +851,7 @@ EXTRA_DIST =                                \
        linux/syscall.h                 \
        linux/syscallent-common-32.h    \
        linux/syscallent-common.h       \
+       linux/syscallent_base_nr.h      \
        linux/tile/arch_defs_.h         \
        linux/tile/arch_get_personality.c \
        linux/tile/arch_regs.c          \

diff --git a/clone.c b/clone.c
index e74a53ce71e051e420985b5772b1acb2ec2b6b01..3da54a2a9ba4162620311156f3e4df1798f91d2a 100644 (file)
--- a/clone.c
+++ b/clone.c
@@ -25,10 +25,10 @@
 #if defined IA64
 # define ARG_FLAGS     0
 # define ARG_STACK     1
-# define ARG_STACKSIZE (tcp->scno == __NR_clone2 ? 2 : -1)
-# define ARG_PTID      (tcp->scno == __NR_clone2 ? 3 : 2)
-# define ARG_CTID      (tcp->scno == __NR_clone2 ? 4 : 3)
-# define ARG_TLS       (tcp->scno == __NR_clone2 ? 5 : 4)
+# define ARG_STACKSIZE (shuffle_scno(tcp->scno) == __NR_clone2 ? 2 : -1)
+# define ARG_PTID      (shuffle_scno(tcp->scno) == __NR_clone2 ? 3 : 2)
+# define ARG_CTID      (shuffle_scno(tcp->scno) == __NR_clone2 ? 4 : 3)
+# define ARG_TLS       (shuffle_scno(tcp->scno) == __NR_clone2 ? 5 : 4)
 #elif defined S390 || defined S390X
 # define ARG_STACK     0
 # define ARG_FLAGS     1

diff --git a/linux/ia64/shuffle_scno.c b/linux/ia64/shuffle_scno.c
new file mode 100644 (file)
index 0000000..6bac3a8
--- /dev/null
+++ b/linux/ia64/shuffle_scno.c
@@ -0,0 +1,11 @@
+static_assert(!(SYSCALLENT_BASE_NR & (SYSCALLENT_BASE_NR - 1)),
+             "SYSCALLENT_BASE_NR is not a power of 2 (or zero)");
+static_assert(nsyscalls0 < SYSCALLENT_BASE_NR,
+             "syscall table is too big, "
+             "shuffling will only make everything worse");
+
+kernel_ulong_t
+shuffle_scno(kernel_ulong_t scno)
+{
+       return scno ^ SYSCALLENT_BASE_NR;
+}

diff --git a/linux/ia64/syscallent.h b/linux/ia64/syscallent.h
index 86f7efd7a1c73f2bea8ef9256c29f9107e1a0235..8a1388609a35d28bcbbd019ef1ec2218161c48fb 100644 (file)
--- a/linux/ia64/syscallent.h
+++ b/linux/ia64/syscallent.h
@@ -7,7 +7,19 @@
  * SPDX-License-Identifier: LGPL-2.1-or-later
  */
 
-#define BASE_NR 1024
+#ifdef SYSCALLENT_BASE_NR
+/*
+ * The syscallent table starts from 0 because
+ * it is optimized for use with shuffle_scno.
+ */
+# define BASE_NR 0
+#else
+/*
+ * __NR_* constants start from 1024 as usual.
+ * (1U << 10) cannot be used here because SCNO_SED is not smart enough.
+ */
+# define BASE_NR 1024
+#endif
 [BASE_NR +   0] = { 0, 0,              SEN(printargs),                 "ni_syscall"            },
 [BASE_NR +   1] = { 1, TP|SE,          SEN(exit),                      "exit"                  },
 [BASE_NR +   2] = { 3, TD,             SEN(read),                      "read"                  },

diff --git a/linux/ia64/syscallent_base_nr.h b/linux/ia64/syscallent_base_nr.h
new file mode 100644 (file)
index 0000000..612668e
--- /dev/null
+++ b/linux/ia64/syscallent_base_nr.h
@@ -0,0 +1 @@
+#define SYSCALLENT_BASE_NR (1U << 10)

diff --git a/linux/syscallent_base_nr.h b/linux/syscallent_base_nr.h
new file mode 100644 (file)
index 0000000..da84fa5
--- /dev/null
+++ b/linux/syscallent_base_nr.h
@@ -0,0 +1 @@
+/* nothing */

diff --git a/syscall.c b/syscall.c
index a67d7442dc4889398a2a8b424cf1dd303921f1f0..77f73cd03a88dc407f2412b2f04ed54e0c802017 100644 (file)
--- a/syscall.c
+++ b/syscall.c
@@ -41,6 +41,7 @@
 
 #include "syscall.h"
 #include "xstring.h"
+#include "syscallent_base_nr.h"
 
 /* Define these shorthand notations to simplify the syscallent files. */
 #include "sysent_shorthand_defs.h"