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ARM: 7456/1: ptrace: provide separate functions for tracing syscall {entry,exit}

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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>
This commit is contained in:
Will Deacon 2012-07-06 15:50:14 +01:00 committed by Russell King
parent 5125430ccc
commit ad72254114
2 changed files with 32 additions and 21 deletions
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14
arch/arm/kernel/entry-common.S
View file

@ -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

39
arch/arm/kernel/ptrace.c
View file

@ -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;
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;
return current_thread_info()->syscall;
}
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;
}