[RFC][ATCH 3/3] syscalls: Remove start and number from syscall_get_arguments() args

From: Steven Rostedt
Date: Mon Nov 07 2016 - 16:34:27 EST

From: Steven Rostedt <rostedt@xxxxxxxxxxx>

At Linux Plumbers, Andy Lutomirski approached me and pointed out that the
function call syscall_get_arguments() implemented in x86 was horribly
written and not optimized for the standard case of passing in 0 and 6 for
the starting index and the number of system calls to get. When looking at
all the users of this function, I discovered that all instances pass in only
0 and 6 for these arguments. Instead of having this function handle
different cases that are never used, simply rewrite it to return the first 6
arguments of a system call.

This should help out the performance of tracing system calls by ptrace,
ftrace and perf.

Reported-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
arch/arc/include/asm/syscall.h | 7 ++--
arch/arm/include/asm/syscall.h | 23 ++---------
arch/arm64/include/asm/syscall.h | 22 ++---------
arch/blackfin/include/asm/syscall.h | 22 +++++++----
arch/c6x/include/asm/syscall.h | 41 ++++----------------
arch/frv/include/asm/syscall.h | 26 +++----------
arch/h8300/include/asm/syscall.h | 34 ++++-------------
arch/hexagon/include/asm/syscall.h | 4 +-
arch/ia64/include/asm/syscall.h | 5 +--
arch/metag/include/asm/syscall.h | 4 +-
arch/microblaze/include/asm/syscall.h | 4 +-
arch/mips/include/asm/syscall.h | 3 +-
arch/mn10300/include/asm/syscall.h | 32 +++-------------
arch/nios2/include/asm/syscall.h | 42 ++++----------------
arch/openrisc/include/asm/syscall.h | 6 +--
arch/parisc/include/asm/syscall.h | 30 ++++-----------
arch/powerpc/include/asm/syscall.h | 8 ++--
arch/s390/include/asm/syscall.h | 11 +++---
arch/sh/include/asm/syscall_32.h | 26 +++----------
arch/sh/include/asm/syscall_64.h | 4 +-
arch/sparc/include/asm/syscall.h | 4 +-
arch/tile/include/asm/syscall.h | 4 +-
arch/um/include/asm/syscall-generic.h | 39 +++----------------
arch/x86/include/asm/syscall.h | 72 ++++++++---------------------------
include/asm-generic/syscall.h | 11 ++----
include/trace/events/syscalls.h | 2 +-
kernel/seccomp.c | 2 +-
kernel/trace/trace_syscalls.c | 4 +-
lib/syscall.c | 2 +-
29 files changed, 124 insertions(+), 370 deletions(-)

diff --git a/arch/arc/include/asm/syscall.h b/arch/arc/include/asm/syscall.h
index 29de09804306..c7a4201ed62b 100644
--- a/arch/arc/include/asm/syscall.h
+++ b/arch/arc/include/asm/syscall.h
@@ -55,12 +55,11 @@ syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
*/
static inline void
syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
- unsigned int i, unsigned int n, unsigned long *args)
+ unsigned long *args)
{
unsigned long *inside_ptregs = &(regs->r0);
- inside_ptregs -= i;
-
- BUG_ON((i + n) > 6);
+ unsigned int n = 6;
+ unsigned int i = 0;

while (n--) {
args[i++] = (*inside_ptregs);
diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h
index e86c985b8c7a..1521b465b581 100644
--- a/arch/arm/include/asm/syscall.h
+++ b/arch/arm/include/asm/syscall.h
@@ -54,29 +54,14 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
- if (n == 0)
- return;
-
- if (i + n > SYSCALL_MAX_ARGS) {
- unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
- unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
- pr_warn("%s called with max args %d, handling only %d\n",
- __func__, i + n, SYSCALL_MAX_ARGS);
- memset(args_bad, 0, n_bad * sizeof(args[0]));
- n = SYSCALL_MAX_ARGS - i;
- }
+ unsigned int n;

- if (i == 0) {
- args[0] = regs->ARM_ORIG_r0;
- args++;
- i++;
- n--;
- }
+ args[0] = regs->ARM_ORIG_r0;
+ args++;

- memcpy(args, &regs->ARM_r0 + i, n * sizeof(args[0]));
+ memcpy(args, &regs->ARM_r0 + 1, 5 * sizeof(args[0]));
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index 709a574468f0..fb6668df435b 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -59,28 +59,12 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
- if (n == 0)
- return;
-
- if (i + n > SYSCALL_MAX_ARGS) {
- unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i;
- unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
- pr_warning("%s called with max args %d, handling only %d\n",
- __func__, i + n, SYSCALL_MAX_ARGS);
- memset(args_bad, 0, n_bad * sizeof(args[0]));
- }
-
- if (i == 0) {
- args[0] = regs->orig_x0;
- args++;
- i++;
- n--;
- }
+ args[0] = regs->orig_x0;
+ args++;

- memcpy(args, &regs->regs[i], n * sizeof(args[0]));
+ memcpy(args, &regs->regs[1], 5 * sizeof(args[0]));
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/arch/blackfin/include/asm/syscall.h b/arch/blackfin/include/asm/syscall.h
index 4921a4815cce..cef32063f54b 100644
--- a/arch/blackfin/include/asm/syscall.h
+++ b/arch/blackfin/include/asm/syscall.h
@@ -57,30 +57,36 @@ syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
* syscall_get_arguments()
* @task: unused
* @regs: the register layout to extract syscall arguments from
- * @i: first syscall argument to extract
- * @n: number of syscall arguments to extract
* @args: array to return the syscall arguments in
*
- * args[0] gets i'th argument, args[n - 1] gets the i+n-1'th argument
+ * Gets the 6 arguments of the system call
*/
static inline void
syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
- unsigned int i, unsigned int n, unsigned long *args)
+ unsigned long *args)
{
/*
* Assume the ptrace layout doesn't change -- r5 is first in memory,
* then r4, ..., then r0. So we simply reverse the ptrace register
* array in memory to store into the args array.
*/
- long *aregs = &regs->r0 - i;
-
- BUG_ON(i > 5 || i + n > 6);
+ long *aregs = &regs->r0;
+ unsigned int n = 6;

while (n--)
*args++ = *aregs--;
}

-/* See syscall_get_arguments() comments */
+/**
+ * syscall_set_arguments()
+ * @task: unused
+ * @regs: the register layout to extract syscall arguments from
+ * @i: first syscall argument to extract
+ * @n: number of syscall arguments to extract
+ * @args: array to return the syscall arguments in
+ *
+ * args[0] gets i'th argument, args[n - 1] gets the i+n-1'th argument
+ */
static inline void
syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
unsigned int i, unsigned int n, const unsigned long *args)
diff --git a/arch/c6x/include/asm/syscall.h b/arch/c6x/include/asm/syscall.h
index ae2be315ee9c..06db3251926b 100644
--- a/arch/c6x/include/asm/syscall.h
+++ b/arch/c6x/include/asm/syscall.h
@@ -46,40 +46,15 @@ static inline void syscall_set_return_value(struct task_struct *task,
}

static inline void syscall_get_arguments(struct task_struct *task,
- struct pt_regs *regs, unsigned int i,
- unsigned int n, unsigned long *args)
+ struct pt_regs *regs,
+ unsigned long *args)
{
- switch (i) {
- case 0:
- if (!n--)
- break;
- *args++ = regs->a4;
- case 1:
- if (!n--)
- break;
- *args++ = regs->b4;
- case 2:
- if (!n--)
- break;
- *args++ = regs->a6;
- case 3:
- if (!n--)
- break;
- *args++ = regs->b6;
- case 4:
- if (!n--)
- break;
- *args++ = regs->a8;
- case 5:
- if (!n--)
- break;
- *args++ = regs->b8;
- case 6:
- if (!n--)
- break;
- default:
- BUG();
- }
+ *args++ = regs->a4;
+ *args++ = regs->b4;
+ *args++ = regs->a6;
+ *args++ = regs->b6;
+ *args++ = regs->a8;
+ *args = regs->b8;
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/arch/frv/include/asm/syscall.h b/arch/frv/include/asm/syscall.h
index 70689eb29b98..4778fa399f52 100644
--- a/arch/frv/include/asm/syscall.h
+++ b/arch/frv/include/asm/syscall.h
@@ -71,29 +71,15 @@ static inline void syscall_set_return_value(struct task_struct *task,
*/
static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
- /*
- * Do this simply for now. If we need to start supporting
- * fetching arguments from arbitrary indices, this will need some
- * extra logic. Presently there are no in-tree users that depend
- * on this behaviour.
- */
- BUG_ON(i);
-
/* Argument pattern is: GR8, GR9, GR10, GR11, GR12, GR13 */
- switch (n) {
- case 6: args[5] = regs->gr13;
- case 5: args[4] = regs->gr12;
- case 4: args[3] = regs->gr11;
- case 3: args[2] = regs->gr10;
- case 2: args[1] = regs->gr9;
- case 1: args[0] = regs->gr8;
- break;
- default:
- BUG();
- }
+ args[5] = regs->gr13;
+ args[4] = regs->gr12;
+ args[3] = regs->gr11;
+ args[2] = regs->gr10;
+ args[1] = regs->gr9;
+ args[0] = regs->gr8;
}

/*
diff --git a/arch/h8300/include/asm/syscall.h b/arch/h8300/include/asm/syscall.h
index b41f688d02cf..c0bb2e4c152f 100644
--- a/arch/h8300/include/asm/syscall.h
+++ b/arch/h8300/include/asm/syscall.h
@@ -16,34 +16,14 @@ syscall_get_nr(struct task_struct *task, struct pt_regs *regs)

static inline void
syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
- unsigned int i, unsigned int n, unsigned long *args)
+ unsigned long *args)
{
- BUG_ON(i + n > 6);
-
- while (n > 0) {
- switch (i) {
- case 0:
- *args++ = regs->er1;
- break;
- case 1:
- *args++ = regs->er2;
- break;
- case 2:
- *args++ = regs->er3;
- break;
- case 3:
- *args++ = regs->er4;
- break;
- case 4:
- *args++ = regs->er5;
- break;
- case 5:
- *args++ = regs->er6;
- break;
- }
- i++;
- n--;
- }
+ *args++ = regs->er1;
+ *args++ = regs->er2;
+ *args++ = regs->er3;
+ *args++ = regs->er4;
+ *args++ = regs->er5;
+ *args = regs->er6;
}


diff --git a/arch/hexagon/include/asm/syscall.h b/arch/hexagon/include/asm/syscall.h
index 4af9c7b6f13a..ae3a1e24fabd 100644
--- a/arch/hexagon/include/asm/syscall.h
+++ b/arch/hexagon/include/asm/syscall.h
@@ -37,10 +37,8 @@ static inline long syscall_get_nr(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
- BUG_ON(i + n > 6);
- memcpy(args, &(&regs->r00)[i], n * sizeof(args[0]));
+ memcpy(args, &(&regs->r00)[0], 6 * sizeof(args[0]));
}
#endif
diff --git a/arch/ia64/include/asm/syscall.h b/arch/ia64/include/asm/syscall.h
index 1d0b875fec44..8204c1ff70ce 100644
--- a/arch/ia64/include/asm/syscall.h
+++ b/arch/ia64/include/asm/syscall.h
@@ -63,12 +63,9 @@ extern void ia64_syscall_get_set_arguments(struct task_struct *task,
unsigned long *args, int rw);
static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
- BUG_ON(i + n > 6);
-
- ia64_syscall_get_set_arguments(task, regs, i, n, args, 0);
+ ia64_syscall_get_set_arguments(task, regs, 0, 6, args, 0);
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/arch/metag/include/asm/syscall.h b/arch/metag/include/asm/syscall.h
index 24fc97939f77..981bf74c2ec5 100644
--- a/arch/metag/include/asm/syscall.h
+++ b/arch/metag/include/asm/syscall.h
@@ -66,13 +66,11 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
unsigned int reg, j;
- BUG_ON(i + n > 6);

- for (j = i, reg = 6 - i; j < (i + n); j++, reg--) {
+ for (j = 0, reg = 6; j < 6; j++, reg--) {
if (reg % 2)
args[j] = regs->ctx.DX[(reg + 1) / 2].U0;
else
diff --git a/arch/microblaze/include/asm/syscall.h b/arch/microblaze/include/asm/syscall.h
index 04a5bece8168..ec2b0be2076e 100644
--- a/arch/microblaze/include/asm/syscall.h
+++ b/arch/microblaze/include/asm/syscall.h
@@ -81,9 +81,11 @@ static inline void microblaze_set_syscall_arg(struct pt_regs *regs,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
+ unsigned int i = 0;
+ unsigned int n = 6;
+
while (n--)
*args++ = microblaze_get_syscall_arg(regs, i++);
}
diff --git a/arch/mips/include/asm/syscall.h b/arch/mips/include/asm/syscall.h
index d87882513ee3..279878f58191 100644
--- a/arch/mips/include/asm/syscall.h
+++ b/arch/mips/include/asm/syscall.h
@@ -94,9 +94,10 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
+ unsigned int i = 0;
+ unsigned int n = 6;
int ret;
/* O32 ABI syscall() - Either 64-bit with O32 or 32-bit */
if ((IS_ENABLED(CONFIG_32BIT) ||
diff --git a/arch/mn10300/include/asm/syscall.h b/arch/mn10300/include/asm/syscall.h
index b44b0bb75a01..0b2767144a60 100644
--- a/arch/mn10300/include/asm/syscall.h
+++ b/arch/mn10300/include/asm/syscall.h
@@ -52,34 +52,14 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
- switch (i) {
- case 0:
- if (!n--) break;
- *args++ = regs->a0;
- case 1:
- if (!n--) break;
- *args++ = regs->d1;
- case 2:
- if (!n--) break;
- *args++ = regs->a3;
- case 3:
- if (!n--) break;
- *args++ = regs->a2;
- case 4:
- if (!n--) break;
- *args++ = regs->d3;
- case 5:
- if (!n--) break;
- *args++ = regs->d2;
- case 6:
- if (!n--) break;
- default:
- BUG();
- break;
- }
+ *args++ = regs->a0;
+ *args++ = regs->d1;
+ *args++ = regs->a3;
+ *args++ = regs->a2;
+ *args++ = regs->d3;
+ *args = regs->d2;
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/arch/nios2/include/asm/syscall.h b/arch/nios2/include/asm/syscall.h
index 9de220854c4a..964603805cbd 100644
--- a/arch/nios2/include/asm/syscall.h
+++ b/arch/nios2/include/asm/syscall.h
@@ -58,42 +58,14 @@ static inline void syscall_set_return_value(struct task_struct *task,
}

static inline void syscall_get_arguments(struct task_struct *task,
- struct pt_regs *regs, unsigned int i, unsigned int n,
- unsigned long *args)
+ struct pt_regs *regs, unsigned long *args)
{
- BUG_ON(i + n > 6);
-
- switch (i) {
- case 0:
- if (!n--)
- break;
- *args++ = regs->r4;
- case 1:
- if (!n--)
- break;
- *args++ = regs->r5;
- case 2:
- if (!n--)
- break;
- *args++ = regs->r6;
- case 3:
- if (!n--)
- break;
- *args++ = regs->r7;
- case 4:
- if (!n--)
- break;
- *args++ = regs->r8;
- case 5:
- if (!n--)
- break;
- *args++ = regs->r9;
- case 6:
- if (!n--)
- break;
- default:
- BUG();
- }
+ *args++ = regs->r4;
+ *args++ = regs->r5;
+ *args++ = regs->r6;
+ *args++ = regs->r7;
+ *args++ = regs->r8;
+ *args++ = regs->r9;
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/arch/openrisc/include/asm/syscall.h b/arch/openrisc/include/asm/syscall.h
index 2db9f1cf0694..72607860cd55 100644
--- a/arch/openrisc/include/asm/syscall.h
+++ b/arch/openrisc/include/asm/syscall.h
@@ -56,11 +56,9 @@ syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,

static inline void
syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
- unsigned int i, unsigned int n, unsigned long *args)
+ unsigned long *args)
{
- BUG_ON(i + n > 6);
-
- memcpy(args, &regs->gpr[3 + i], n * sizeof(args[0]));
+ memcpy(args, &regs->gpr[3], 6 * sizeof(args[0]));
}

static inline void
diff --git a/arch/parisc/include/asm/syscall.h b/arch/parisc/include/asm/syscall.h
index 5e0b4e6bd99d..f7296bf30eb4 100644
--- a/arch/parisc/include/asm/syscall.h
+++ b/arch/parisc/include/asm/syscall.h
@@ -17,29 +17,15 @@ static inline long syscall_get_nr(struct task_struct *tsk,
}

static inline void syscall_get_arguments(struct task_struct *tsk,
- struct pt_regs *regs, unsigned int i,
- unsigned int n, unsigned long *args)
+ struct pt_regs *regs,
+ unsigned long *args)
{
- BUG_ON(i);
-
- switch (n) {
- case 6:
- args[5] = regs->gr[21];
- case 5:
- args[4] = regs->gr[22];
- case 4:
- args[3] = regs->gr[23];
- case 3:
- args[2] = regs->gr[24];
- case 2:
- args[1] = regs->gr[25];
- case 1:
- args[0] = regs->gr[26];
- case 0:
- break;
- default:
- BUG();
- }
+ args[5] = regs->gr[21];
+ args[4] = regs->gr[22];
+ args[3] = regs->gr[23];
+ args[2] = regs->gr[24];
+ args[1] = regs->gr[25];
+ args[0] = regs->gr[26];
}

static inline long syscall_get_return_value(struct task_struct *task,
diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h
index ab9f3f0a8637..70dcb199c47c 100644
--- a/arch/powerpc/include/asm/syscall.h
+++ b/arch/powerpc/include/asm/syscall.h
@@ -66,22 +66,20 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
unsigned long val, mask = -1UL;
-
- BUG_ON(i + n > 6);
+ unsigned int n = 6;

#ifdef CONFIG_COMPAT
if (test_tsk_thread_flag(task, TIF_32BIT))
mask = 0xffffffff;
#endif
while (n--) {
- if (n == 0 && i == 0)
+ if (n == 0)
val = regs->orig_gpr3;
else
- val = regs->gpr[3 + i + n];
+ val = regs->gpr[3 + n];

args[n] = val & mask;
}
diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
index 6ba0bf928909..2b520aa8ad62 100644
--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -59,21 +59,20 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
unsigned long mask = -1UL;
+ unsigned int n = 6;

- BUG_ON(i + n > 6);
#ifdef CONFIG_COMPAT
if (test_tsk_thread_flag(task, TIF_31BIT))
mask = 0xffffffff;
#endif
while (n-- > 0)
- if (i + n > 0)
- args[n] = regs->gprs[2 + i + n] & mask;
- if (i == 0)
- args[0] = regs->orig_gpr2 & mask;
+ if (n > 0)
+ args[n] = regs->gprs[2 + n] & mask;
+
+ args[0] = regs->orig_gpr2 & mask;
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/arch/sh/include/asm/syscall_32.h b/arch/sh/include/asm/syscall_32.h
index 95be3b0ce0ac..09f4942c1b11 100644
--- a/arch/sh/include/asm/syscall_32.h
+++ b/arch/sh/include/asm/syscall_32.h
@@ -47,30 +47,16 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
- /*
- * Do this simply for now. If we need to start supporting
- * fetching arguments from arbitrary indices, this will need some
- * extra logic. Presently there are no in-tree users that depend
- * on this behaviour.
- */
- BUG_ON(i);

/* Argument pattern is: R4, R5, R6, R7, R0, R1 */
- switch (n) {
- case 6: args[5] = regs->regs[1];
- case 5: args[4] = regs->regs[0];
- case 4: args[3] = regs->regs[7];
- case 3: args[2] = regs->regs[6];
- case 2: args[1] = regs->regs[5];
- case 1: args[0] = regs->regs[4];
- case 0:
- break;
- default:
- BUG();
- }
+ args[5] = regs->regs[1];
+ args[4] = regs->regs[0];
+ args[3] = regs->regs[7];
+ args[2] = regs->regs[6];
+ args[1] = regs->regs[5];
+ args[0] = regs->regs[4];
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/arch/sh/include/asm/syscall_64.h b/arch/sh/include/asm/syscall_64.h
index c6a797b90b80..0c5d28f47827 100644
--- a/arch/sh/include/asm/syscall_64.h
+++ b/arch/sh/include/asm/syscall_64.h
@@ -46,11 +46,9 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
- BUG_ON(i + n > 6);
- memcpy(args, &regs->regs[2 + i], n * sizeof(args[0]));
+ memcpy(args, &regs->regs[2], 6 * sizeof(args[0]));
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/arch/sparc/include/asm/syscall.h b/arch/sparc/include/asm/syscall.h
index 1757cd6c521b..419ed27ae60b 100644
--- a/arch/sparc/include/asm/syscall.h
+++ b/arch/sparc/include/asm/syscall.h
@@ -95,11 +95,11 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
int zero_extend = 0;
unsigned int j;
+ unsigned int n = 6;

#ifdef CONFIG_SPARC64
if (test_tsk_thread_flag(task, TIF_32BIT))
@@ -107,7 +107,7 @@ static inline void syscall_get_arguments(struct task_struct *task,
#endif

for (j = 0; j < n; j++) {
- unsigned long val = regs->u_regs[UREG_I0 + i + j];
+ unsigned long val = regs->u_regs[UREG_I0 + j];

if (zero_extend)
args[j] = (u32) val;
diff --git a/arch/tile/include/asm/syscall.h b/arch/tile/include/asm/syscall.h
index 373d73064ea1..42c6204b3c30 100644
--- a/arch/tile/include/asm/syscall.h
+++ b/arch/tile/include/asm/syscall.h
@@ -76,11 +76,9 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
- BUG_ON(i + n > 6);
- memcpy(args, &regs[i], n * sizeof(args[0]));
+ memcpy(args, &regs[0], 6 * sizeof(args[0]));
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/arch/um/include/asm/syscall-generic.h b/arch/um/include/asm/syscall-generic.h
index 9fb9cf8cd39a..25d00acd1322 100644
--- a/arch/um/include/asm/syscall-generic.h
+++ b/arch/um/include/asm/syscall-generic.h
@@ -53,43 +53,16 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
const struct uml_pt_regs *r = &regs->regs;

- switch (i) {
- case 0:
- if (!n--)
- break;
- *args++ = UPT_SYSCALL_ARG1(r);
- case 1:
- if (!n--)
- break;
- *args++ = UPT_SYSCALL_ARG2(r);
- case 2:
- if (!n--)
- break;
- *args++ = UPT_SYSCALL_ARG3(r);
- case 3:
- if (!n--)
- break;
- *args++ = UPT_SYSCALL_ARG4(r);
- case 4:
- if (!n--)
- break;
- *args++ = UPT_SYSCALL_ARG5(r);
- case 5:
- if (!n--)
- break;
- *args++ = UPT_SYSCALL_ARG6(r);
- case 6:
- if (!n--)
- break;
- default:
- BUG();
- break;
- }
+ *args++ = UPT_SYSCALL_ARG1(r);
+ *args++ = UPT_SYSCALL_ARG2(r);
+ *args++ = UPT_SYSCALL_ARG3(r);
+ *args++ = UPT_SYSCALL_ARG4(r);
+ *args++ = UPT_SYSCALL_ARG5(r);
+ *args = UPT_SYSCALL_ARG6(r);
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
index e3c95e8e61c5..050891169b51 100644
--- a/arch/x86/include/asm/syscall.h
+++ b/arch/x86/include/asm/syscall.h
@@ -87,11 +87,9 @@ static inline void syscall_set_return_value(struct task_struct *task,

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
- BUG_ON(i + n > 6);
- memcpy(args, &regs->bx + i, n * sizeof(args[0]));
+ memcpy(args, &regs->bx, 6 * sizeof(args[0]));
}

static inline void syscall_set_arguments(struct task_struct *task,
@@ -112,63 +110,25 @@ static inline int syscall_get_arch(void)

static inline void syscall_get_arguments(struct task_struct *task,
struct pt_regs *regs,
- unsigned int i, unsigned int n,
unsigned long *args)
{
# ifdef CONFIG_IA32_EMULATION
- if (task->thread.status & TS_COMPAT)
- switch (i) {
- case 0:
- if (!n--) break;
- *args++ = regs->bx;
- case 1:
- if (!n--) break;
- *args++ = regs->cx;
- case 2:
- if (!n--) break;
- *args++ = regs->dx;
- case 3:
- if (!n--) break;
- *args++ = regs->si;
- case 4:
- if (!n--) break;
- *args++ = regs->di;
- case 5:
- if (!n--) break;
- *args++ = regs->bp;
- case 6:
- if (!n--) break;
- default:
- BUG();
- break;
- }
- else
+ if (task->thread.status & TS_COMPAT) {
+ *args++ = regs->bx;
+ *args++ = regs->cx;
+ *args++ = regs->dx;
+ *args++ = regs->si;
+ *args++ = regs->di;
+ *args = regs->bp;
+ } else {
# endif
- switch (i) {
- case 0:
- if (!n--) break;
- *args++ = regs->di;
- case 1:
- if (!n--) break;
- *args++ = regs->si;
- case 2:
- if (!n--) break;
- *args++ = regs->dx;
- case 3:
- if (!n--) break;
- *args++ = regs->r10;
- case 4:
- if (!n--) break;
- *args++ = regs->r8;
- case 5:
- if (!n--) break;
- *args++ = regs->r9;
- case 6:
- if (!n--) break;
- default:
- BUG();
- break;
- }
+ *args++ = regs->di;
+ *args++ = regs->si;
+ *args++ = regs->dx;
+ *args++ = regs->r10;
+ *args++ = regs->r8;
+ *args = regs->r9;
+ }
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h
index 0c938a4354f6..269e9412ef42 100644
--- a/include/asm-generic/syscall.h
+++ b/include/asm-generic/syscall.h
@@ -105,21 +105,16 @@ void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
* syscall_get_arguments - extract system call parameter values
* @task: task of interest, must be blocked
* @regs: task_pt_regs() of @task
- * @i: argument index [0,5]
- * @n: number of arguments; n+i must be [1,6].
* @args: array filled with argument values
*
- * Fetches @n arguments to the system call starting with the @i'th argument
- * (from 0 through 5). Argument @i is stored in @args[0], and so on.
- * An arch inline version is probably optimal when @i and @n are constants.
+ * Fetches 6 arguments to the system call. First argument is stored in
+* @args[0], and so on.
*
* It's only valid to call this when @task is stopped for tracing on
* entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
- * It's invalid to call this with @i + @n > 6; we only support system calls
- * taking up to 6 arguments.
*/
void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
- unsigned int i, unsigned int n, unsigned long *args);
+ unsigned long *args);

/**
* syscall_set_arguments - change system call parameter value
diff --git a/include/trace/events/syscalls.h b/include/trace/events/syscalls.h
index 14e49c798135..72aa1694a6cf 100644
--- a/include/trace/events/syscalls.h
+++ b/include/trace/events/syscalls.h
@@ -26,7 +26,7 @@ TRACE_EVENT_FN(sys_enter,

TP_fast_assign(
__entry->id = id;
- syscall_get_arguments(current, regs, 0, 6, __entry->args);
+ syscall_get_arguments(current, regs, __entry->args);
),

TP_printk("NR %ld (%lx, %lx, %lx, %lx, %lx, %lx)",
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 0db7c8a2afe2..31d1a3c04bec 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -75,7 +75,7 @@ static void populate_seccomp_data(struct seccomp_data *sd)

sd->nr = syscall_get_nr(task, regs);
sd->arch = syscall_get_arch();
- syscall_get_arguments(task, regs, 0, 6, args);
+ syscall_get_arguments(task, regs, args);
sd->args[0] = args[0];
sd->args[1] = args[1];
sd->args[2] = args[2];
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 52c1503cedfa..3aff1f5e7fc3 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -347,7 +347,7 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)

entry = ring_buffer_event_data(event);
entry->nr = syscall_nr;
- syscall_get_arguments(current, regs, 0, 6, args);
+ syscall_get_arguments(current, regs, args);
memcpy(entry->args, args, sizeof(unsigned long) * sys_data->nb_args);

event_trigger_unlock_commit(trace_file, buffer, event, entry,
@@ -595,7 +595,7 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
return;

rec->nr = syscall_nr;
- syscall_get_arguments(current, regs, 0, 6, args);
+ syscall_get_arguments(current, regs, args);
memcpy(&rec->args, args, sizeof(unsigned long) * sys_data->nb_args);

perf_trace_buf_submit(rec, size, rctx,
diff --git a/lib/syscall.c b/lib/syscall.c
index cbd376c66bbc..cc83c9e2d682 100644
--- a/lib/syscall.c
+++ b/lib/syscall.c
@@ -26,7 +26,7 @@ static int collect_syscall(struct task_struct *target, long *callno,

*callno = syscall_get_nr(target, regs);
if (*callno != -1L)
- syscall_get_arguments(target, regs, 0, 6, args);
+ syscall_get_arguments(target, regs, args);

put_task_stack(target);
return 0;
--
2.9.3