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SubjectRe: [PATCH 00/12] add syscall tracepoints V3 - s390 arch update
On Tue, Aug 25, 2009 at 02:31:11PM +0200, Hendrik Brueckner wrote:
> Hi,
>
> I looked at your recent syscall tracepoint patches and I have few
> more s390 arch updates.
>
> This patch includes s390 arch updates for:
> - tracing: Map syscall name to number (syscall_name_to_nr())
> - tracing: Call arch_init_ftrace_syscalls at boot
> - tracing: add support traceopint ids (set_syscall_{enter,exit}_id())
>
> The patch already uses "NR_syscalls" instead of FTRACE_SYSCALL_MAX.
>
> The patch is based on today's linux-next (20090825).
> Since few of your patches already include s390 changes,
> I would appreciate if you could add the patch to your patch set.
>
> If you have any remarks, please let me know.
>
> Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>


Looks good at a first glance.



> ---
> arch/s390/include/asm/ftrace.h | 4 ++++
> arch/s390/kernel/ftrace.c | 36 +++++++++++++++++++++++++++---------
> 2 files changed, 31 insertions(+), 9 deletions(-)
>
> --- a/arch/s390/kernel/ftrace.c
> +++ b/arch/s390/kernel/ftrace.c
> @@ -220,6 +220,29 @@ struct syscall_metadata *syscall_nr_to_m
> return syscalls_metadata[nr];
> }
>
> +int syscall_name_to_nr(char *name)
> +{
> + int i;
> +
> + if (!syscalls_metadata)
> + return -1;
> + for (i = 0; i < NR_syscalls; i++)
> + if (syscalls_metadata[i])
> + if (!strcmp(syscalls_metadata[i]->name, name))
> + return i;
> + return -1;
> +}
> +void set_syscall_enter_id(int num, int id)
> +{
> + syscalls_metadata[num]->enter_id = id;
> +}
> +
> +void set_syscall_exit_id(int num, int id)
> +{
> + syscalls_metadata[num]->exit_id = id;
> +}



The three helpers above seem very common between archs, I guess
we can move them to the core: kernel/trace/trace_syscalls.c


> static struct syscall_metadata *find_syscall_meta(unsigned long syscall)
> {
> struct syscall_metadata *start;
> @@ -237,24 +260,19 @@ static struct syscall_metadata *find_sys
> return NULL;
> }
>
> -void arch_init_ftrace_syscalls(void)
> +static int __init arch_init_ftrace_syscalls(void)
> {
> struct syscall_metadata *meta;
> int i;
> - static atomic_t refs;
> -
> - if (atomic_inc_return(&refs) != 1)
> - goto out;
> syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) * NR_syscalls,
> GFP_KERNEL);
> if (!syscalls_metadata)
> - goto out;
> + return -ENOMEM;
> for (i = 0; i < NR_syscalls; i++) {
> meta = find_syscall_meta((unsigned long)sys_call_table[i]);
> syscalls_metadata[i] = meta;
> }
> - return;
> -out:
> - atomic_dec(&refs);
> + return 0;
> }
> +arch_initcall(arch_init_ftrace_syscalls);
> #endif



We can even probably move most of this code to the core, expect the tiny parts
that rely on the arch syscall table.

BTW, perhaps a silly question: would it be hard to have a generic syscall table
common to every archs?

Thanks,
Frederic.



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