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authorAKASHI Takahiro <takahiro.akashi@linaro.org>2014-11-28 05:26:34 +0000
committerWill Deacon <will.deacon@arm.com>2014-11-28 10:19:49 +0000
commit766a85d7bc5d7f1ddd6de28bdb844eae45ec63b0 (patch)
tree3445af3c028dbaae227fcd3f74d45b80da115b8a /arch/arm64/kernel/ptrace.c
parent034edabe6cf1d0dea49d4c836ba128cec90fad04 (diff)
arm64: ptrace: add NT_ARM_SYSTEM_CALL regset
This regeset is intended to be used to get and set a system call number while tracing. There was some discussion about possible approaches to do so: (1) modify x8 register with ptrace(PTRACE_SETREGSET) indirectly, and update regs->syscallno later on in syscall_trace_enter(), or (2) define a dedicated regset for this purpose as on s390, or (3) support ptrace(PTRACE_SET_SYSCALL) as on arch/arm Thinking of the fact that user_pt_regs doesn't expose 'syscallno' to tracer as well as that secure_computing() expects a changed syscall number, especially case of -1, to be visible before this function returns in syscall_trace_enter(), (1) doesn't work well. We will take (2) since it looks much cleaner. Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/ptrace.c')
-rw-r--r--arch/arm64/kernel/ptrace.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 8a4ae8e73213..f576781d8d3b 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -551,6 +551,32 @@ static int tls_set(struct task_struct *target, const struct user_regset *regset,
return ret;
}
+static int system_call_get(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ void *kbuf, void __user *ubuf)
+{
+ int syscallno = task_pt_regs(target)->syscallno;
+
+ return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+ &syscallno, 0, -1);
+}
+
+static int system_call_set(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ const void *kbuf, const void __user *ubuf)
+{
+ int syscallno, ret;
+
+ ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &syscallno, 0, -1);
+ if (ret)
+ return ret;
+
+ task_pt_regs(target)->syscallno = syscallno;
+ return ret;
+}
+
enum aarch64_regset {
REGSET_GPR,
REGSET_FPR,
@@ -559,6 +585,7 @@ enum aarch64_regset {
REGSET_HW_BREAK,
REGSET_HW_WATCH,
#endif
+ REGSET_SYSTEM_CALL,
};
static const struct user_regset aarch64_regsets[] = {
@@ -608,6 +635,14 @@ static const struct user_regset aarch64_regsets[] = {
.set = hw_break_set,
},
#endif
+ [REGSET_SYSTEM_CALL] = {
+ .core_note_type = NT_ARM_SYSTEM_CALL,
+ .n = 1,
+ .size = sizeof(int),
+ .align = sizeof(int),
+ .get = system_call_get,
+ .set = system_call_set,
+ },
};
static const struct user_regset_view user_aarch64_view = {