[RFC][PATCH 3/4 v2] syscalls: Remove start and number from syscall_get_arguments() args

From: Steven Rostedt
Date: Thu Mar 28 2019 - 23:23:03 EST

From: "Steven Rostedt (Red Hat)" <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.

Link: http://lkml.kernel.org/r/20161107213233.754809394@xxxxxxxxxxx

Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
Cc: Dave Martin <dave.martin@xxxxxxx>
Cc: "Dmitry V. Levin" <ldv@xxxxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: linux-snps-arc@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-c6x-dev@xxxxxxxxxxxxx
Cc: uclinux-h8-devel@xxxxxxxxxxxxxxxxxxxx
Cc: linux-hexagon@xxxxxxxxxxxxxxx
Cc: linux-ia64@xxxxxxxxxxxxxxx
Cc: linux-mips@xxxxxxxxxxxxxxx
Cc: nios2-dev@xxxxxxxxxxxxxxxxxxxxxx
Cc: openrisc@xxxxxxxxxxxxxxxxxxxx
Cc: linux-parisc@xxxxxxxxxxxxxxx
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Cc: linux-riscv@xxxxxxxxxxxxxxxxxxx
Cc: linux-s390@xxxxxxxxxxxxxxx
Cc: linux-sh@xxxxxxxxxxxxxxx
Cc: sparclinux@xxxxxxxxxxxxxxx
Cc: linux-um@xxxxxxxxxxxxxxxxxxx
Cc: linux-xtensa@xxxxxxxxxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx
Reported-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
arch/arc/include/asm/syscall.h | 7 ++-
arch/arm/include/asm/syscall.h | 23 ++-------
arch/arm64/include/asm/syscall.h | 22 ++------
arch/c6x/include/asm/syscall.h | 41 +++------------
arch/csky/include/asm/syscall.h | 13 ++---
arch/h8300/include/asm/syscall.h | 34 +++----------
arch/hexagon/include/asm/syscall.h | 4 +-
arch/ia64/include/asm/syscall.h | 5 +-
arch/microblaze/include/asm/syscall.h | 4 +-
arch/mips/include/asm/syscall.h | 3 +-
arch/mips/kernel/ptrace.c | 2 +-
arch/nds32/include/asm/syscall.h | 33 +++---------
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/riscv/include/asm/syscall.h | 12 ++---
arch/s390/include/asm/syscall.h | 17 ++-----
arch/sh/include/asm/syscall_32.h | 26 +++-------
arch/sh/include/asm/syscall_64.h | 4 +-
arch/sparc/include/asm/syscall.h | 4 +-
arch/um/include/asm/syscall-generic.h | 39 +++-----------
arch/x86/include/asm/syscall.h | 73 +++++++--------------------
arch/xtensa/include/asm/syscall.h | 16 ++----
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, 113 insertions(+), 376 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 06dea6bce293..db969a2972ae 100644
--- a/arch/arm/include/asm/syscall.h
+++ b/arch/arm/include/asm/syscall.h
@@ -55,29 +55,12 @@ 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_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;
- }
-
- 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 ad8be16a39c9..55b2dab21023 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -65,28 +65,12 @@ 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/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/csky/include/asm/syscall.h b/arch/csky/include/asm/syscall.h
index d637445737b7..5cc0b8283a69 100644
--- a/arch/csky/include/asm/syscall.h
+++ b/arch/csky/include/asm/syscall.h
@@ -43,16 +43,11 @@ 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)
{
- BUG_ON(i + n > 6);
- if (i == 0) {
- args[0] = regs->orig_a0;
- args++;
- i++;
- n--;
- }
- memcpy(args, &regs->a1 + i * sizeof(regs->a1), n * sizeof(args[0]));
+ args[0] = regs->orig_a0;
+ args++;
+ memcpy(args, &regs->a1 + sizeof(regs->a1), 5 * sizeof(args[0]));
}

static inline void
diff --git a/arch/h8300/include/asm/syscall.h b/arch/h8300/include/asm/syscall.h
index 924990401237..ddd483c6ca95 100644
--- a/arch/h8300/include/asm/syscall.h
+++ b/arch/h8300/include/asm/syscall.h
@@ -17,34 +17,14 @@ 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/microblaze/include/asm/syscall.h b/arch/microblaze/include/asm/syscall.h
index 220decd605a4..4b23e44e5c3c 100644
--- a/arch/microblaze/include/asm/syscall.h
+++ b/arch/microblaze/include/asm/syscall.h
@@ -82,9 +82,11 @@ 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 6cf8ffb5367e..a2b4748655df 100644
--- a/arch/mips/include/asm/syscall.h
+++ b/arch/mips/include/asm/syscall.h
@@ -116,9 +116,10 @@ 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() */
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 0057c910bc2f..3a62f80958e1 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -1419,7 +1419,7 @@ asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall)

sd.nr = syscall;
sd.arch = syscall_get_arch();
- syscall_get_arguments(current, regs, 0, 6, args);
+ syscall_get_arguments(current, regs, args);
for (i = 0; i < 6; i++)
sd.args[i] = args[i];
sd.instruction_pointer = KSTK_EIP(current);
diff --git a/arch/nds32/include/asm/syscall.h b/arch/nds32/include/asm/syscall.h
index f7e5e86765fe..89a6ec8731d8 100644
--- a/arch/nds32/include/asm/syscall.h
+++ b/arch/nds32/include/asm/syscall.h
@@ -108,42 +108,21 @@ 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 (from 0 through 5). The 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.
*/
#define SYSCALL_MAX_ARGS 6
void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
- unsigned int i, unsigned int n, unsigned long *args)
+ 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]));
- memset(args_bad, 0, n_bad * sizeof(args[0]));
- }
-
- if (i == 0) {
- args[0] = regs->orig_r0;
- args++;
- i++;
- n--;
- }
-
- memcpy(args, &regs->uregs[0] + i, n * sizeof(args[0]));
+ args[0] = regs->orig_r0;
+ args++;
+ memcpy(args, &regs->uregs[0] + 1, 5 * sizeof(args[0]));
}

/**
diff --git a/arch/nios2/include/asm/syscall.h b/arch/nios2/include/asm/syscall.h
index 9de220854c4a..792bd449d839 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 8bff1a58c97f..62a6d477fae0 100644
--- a/arch/parisc/include/asm/syscall.h
+++ b/arch/parisc/include/asm/syscall.h
@@ -18,29 +18,15 @@ 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 1a0e7a8b1c81..5c9b9dc82b7e 100644
--- a/arch/powerpc/include/asm/syscall.h
+++ b/arch/powerpc/include/asm/syscall.h
@@ -65,22 +65,20 @@ 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/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h
index bba3da6ef157..85a31dd0f2ba 100644
--- a/arch/riscv/include/asm/syscall.h
+++ b/arch/riscv/include/asm/syscall.h
@@ -72,17 +72,11 @@ 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)
{
- BUG_ON(i + n > 6);
- if (i == 0) {
- args[0] = regs->orig_a0;
- args++;
- i++;
- n--;
- }
- memcpy(args, &regs->a1 + i * sizeof(regs->a1), n * sizeof(args[0]));
+ args[0] = regs->orig_a0;
+ args++;
+ memcpy(args, &regs->a1 + sizeof(regs->a1), 5 * sizeof(args[0]));
}

static inline void syscall_set_arguments(struct task_struct *task,
diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
index 96f9a9151fde..ee0b1f6aa36d 100644
--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -56,27 +56,20 @@ 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;

- /*
- * No arguments for this syscall, there's nothing to do.
- */
- if (!n)
- return;
-
- 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 6e118799831c..2bf1199a0595 100644
--- a/arch/sh/include/asm/syscall_32.h
+++ b/arch/sh/include/asm/syscall_32.h
@@ -48,30 +48,16 @@ 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 43882580c7f9..4e8f6460c703 100644
--- a/arch/sh/include/asm/syscall_64.h
+++ b/arch/sh/include/asm/syscall_64.h
@@ -47,11 +47,9 @@ 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 053989e3f6a6..872dfee852d6 100644
--- a/arch/sparc/include/asm/syscall.h
+++ b/arch/sparc/include/asm/syscall.h
@@ -96,11 +96,11 @@ 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))
@@ -108,7 +108,7 @@ 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/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 d653139857af..8dbb5c379450 100644
--- a/arch/x86/include/asm/syscall.h
+++ b/arch/x86/include/asm/syscall.h
@@ -91,11 +91,9 @@ 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,
@@ -116,63 +114,26 @@ 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_info.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_info.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/arch/xtensa/include/asm/syscall.h b/arch/xtensa/include/asm/syscall.h
index a168bf81c7f4..1504ce9a233a 100644
--- a/arch/xtensa/include/asm/syscall.h
+++ b/arch/xtensa/include/asm/syscall.h
@@ -59,23 +59,13 @@ 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)
{
static const unsigned int reg[] = XTENSA_SYSCALL_ARGUMENT_REGS;
- unsigned int j;
-
- if (n == 0)
- return;
-
- WARN_ON_ONCE(i + n > SYSCALL_MAX_ARGS);
+ unsigned int i;

- for (j = 0; j < n; ++j) {
- if (i + j < SYSCALL_MAX_ARGS)
- args[j] = regs->areg[reg[i + j]];
- else
- args[j] = 0;
- }
+ for (i = 0; i < 6; ++i)
+ args[i] = regs->areg[reg[i]];
}

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 44a3259ed4a5..b6e0cbc2c71f 100644
--- a/include/trace/events/syscalls.h
+++ b/include/trace/events/syscalls.h
@@ -28,7 +28,7 @@ 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 54a0347ca812..df27e499956a 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -149,7 +149,7 @@ 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 e9f5bbbad6d9..fa8fbff736d6 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -348,7 +348,7 @@ 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,
@@ -616,7 +616,7 @@ 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);

if ((valid_prog_array &&
diff --git a/lib/syscall.c b/lib/syscall.c
index e8467e17b9a2..fb328e7ccb08 100644
--- a/lib/syscall.c
+++ b/lib/syscall.c
@@ -27,7 +27,7 @@ static int collect_syscall(struct task_struct *target, struct syscall_info *info

info->data.nr = syscall_get_nr(target, regs);
if (info->data.nr != -1L)
- syscall_get_arguments(target, regs, 0, 6,
+ syscall_get_arguments(target, regs,
(unsigned long *)&info->data.args[0]);

put_task_stack(target);
--
2.20.1