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authorWill Deacon <will.deacon@arm.com>2012-07-06 15:50:14 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2012-07-09 17:44:14 +0100
commitad722541147e6e517a2077e3d944105e7bc4fa8e (patch)
treed69c7f9399e1407ec3300aa73b2467294972a087
parent5125430cccc41f67bfe024394a302901034f6d39 (diff)
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ARM: 7456/1: ptrace: provide separate functions for tracing syscall {entry,exit}
The syscall_trace on ARM takes a `why' parameter to indicate whether or not we are entering or exiting a system call. This can be confusing for people looking at the code since (a) it conflicts with the why register alias in the entry assembly code and (b) it is not immediately clear what it represents. This patch splits up the syscall_trace function into separate wrappers for syscall entry and exit, allowing the low-level syscall handling code to branch to the appropriate function. Reported-by: Al Viro <viro@zeniv.linux.org.uk> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm/kernel/entry-common.S14
-rw-r--r--arch/arm/kernel/ptrace.c37
2 files changed, 31 insertions, 20 deletions
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 10911c93fbf1..49d9f9305247 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -442,10 +442,9 @@ ENDPROC(vector_swi)
* context switches, and waiting for our parent to respond.
*/
__sys_trace:
- mov r2, scno
- add r1, sp, #S_OFF
- mov r0, #0 @ trace entry [IP = 0]
- bl syscall_trace
+ mov r1, scno
+ add r0, sp, #S_OFF
+ bl syscall_trace_enter
adr lr, BSYM(__sys_trace_return) @ return address
mov scno, r0 @ syscall number (possibly new)
@@ -457,10 +456,9 @@ __sys_trace:
__sys_trace_return:
str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
- mov r2, scno
- mov r1, sp
- mov r0, #1 @ trace exit [IP = 1]
- bl syscall_trace
+ mov r1, scno
+ mov r0, sp
+ bl syscall_trace_exit
b ret_slow_syscall
.align 5
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 592a39d0ef31..dab711e6e1ca 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -907,12 +907,18 @@ long arch_ptrace(struct task_struct *child, long request,
return ret;
}
-asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
+enum ptrace_syscall_dir {
+ PTRACE_SYSCALL_ENTER = 0,
+ PTRACE_SYSCALL_EXIT,
+};
+
+static int ptrace_syscall_trace(struct pt_regs *regs, int scno,
+ enum ptrace_syscall_dir dir)
{
unsigned long ip;
if (!test_thread_flag(TIF_SYSCALL_TRACE))
- goto out_no_trace;
+ return scno;
current_thread_info()->syscall = scno;
@@ -921,21 +927,28 @@ asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
* IP = 0 -> entry, =1 -> exit
*/
ip = regs->ARM_ip;
- regs->ARM_ip = why;
+ regs->ARM_ip = dir;
- if (why)
+ if (dir == PTRACE_SYSCALL_EXIT)
tracehook_report_syscall_exit(regs, 0);
else if (tracehook_report_syscall_entry(regs))
current_thread_info()->syscall = -1;
regs->ARM_ip = ip;
- scno = current_thread_info()->syscall;
+ return current_thread_info()->syscall;
+}
-out_no_trace:
- if (why)
- audit_syscall_exit(regs);
- else
- audit_syscall_entry(AUDIT_ARCH_ARM, scno, regs->ARM_r0,
- regs->ARM_r1, regs->ARM_r2, regs->ARM_r3);
- return scno;
+asmlinkage int syscall_trace_enter(struct pt_regs *regs, int scno)
+{
+ int ret = ptrace_syscall_trace(regs, scno, PTRACE_SYSCALL_ENTER);
+ audit_syscall_entry(AUDIT_ARCH_ARM, scno, regs->ARM_r0, regs->ARM_r1,
+ regs->ARM_r2, regs->ARM_r3);
+ return ret;
+}
+
+asmlinkage int syscall_trace_exit(struct pt_regs *regs, int scno)
+{
+ int ret = ptrace_syscall_trace(regs, scno, PTRACE_SYSCALL_EXIT);
+ audit_syscall_exit(regs);
+ return ret;
}