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-rw-r--r--Documentation/powerpc/syscall64-abi.rst10
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/powerpc/syscall64-abi.rst b/Documentation/powerpc/syscall64-abi.rst
index dabee3729e5a..56490c4c0c07 100644
--- a/Documentation/powerpc/syscall64-abi.rst
+++ b/Documentation/powerpc/syscall64-abi.rst
@@ -109,6 +109,16 @@ auxiliary vector.
scv 0 syscalls will always behave as PPC_FEATURE2_HTM_NOSC.
+ptrace
+------
+When ptracing system calls (PTRACE_SYSCALL), the pt_regs.trap value contains
+the system call type that can be used to distinguish between sc and scv 0
+system calls, and the different register conventions can be accounted for.
+
+If the value of (pt_regs.trap & 0xfff0) is 0xc00 then the system call was
+performed with the sc instruction, if it is 0x3000 then the system call was
+performed with the scv 0 instruction.
+
vsyscall
========