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    Subject[PATCH 3/6] ftrace syscalls: Make arch_syscall_addr weak
    From: Ian Munsie <>

    Some architectures use non-trivial system call tables and will not work
    with the generic arch_syscall_addr code. For example, PowerPC64 uses a
    table of twin long longs.

    This patch makes the generic arch_syscall_addr weak to allow
    architectures with non-trivial system call tables to override it.

    Signed-off-by: Ian Munsie <>
    Documentation/trace/ftrace-design.txt | 3 +++
    kernel/trace/trace_syscalls.c | 2 +-
    2 files changed, 4 insertions(+), 1 deletions(-)

    diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
    index dc52bd4..6fca17b 100644
    --- a/Documentation/trace/ftrace-design.txt
    +++ b/Documentation/trace/ftrace-design.txt
    @@ -247,6 +247,9 @@ You need very few things to get the syscalls tracing in an arch.
    - Support the TIF_SYSCALL_TRACEPOINT thread flags.
    - Put the trace_sys_enter() and trace_sys_exit() tracepoints calls from ptrace
    in the ptrace syscalls tracing path.
    +- If the system call table on this arch is more complicated than a simple array
    + of addresses of the system calls, implement an arch_syscall_addr to return
    + the address of a given system call.
    - Tag this arch as HAVE_SYSCALL_TRACEPOINTS.

    diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
    index 1a6e8dd..33360b9 100644
    --- a/kernel/trace/trace_syscalls.c
    +++ b/kernel/trace/trace_syscalls.c
    @@ -445,7 +445,7 @@ int init_syscall_trace(struct ftrace_event_call *call)
    return id;

    -unsigned long __init arch_syscall_addr(int nr)
    +unsigned long __init __weak arch_syscall_addr(int nr)
    return (unsigned long)sys_call_table[nr];

     \ /
      Last update: 2011-02-02 08:15    [W:0.019 / U:46.588 seconds]
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