On Sep 9, 2016 1:04 AM, "Marcin Nowakowski"
<marcin.nowakowski@xxxxxxxxxx> wrote:
>
> Extend the syscall tracing subsystem by adding a handler for compat
> tasks. For some architectures, where compat tasks' syscall numbers have
> an exclusive set of syscall numbers, this already works since the
> removal of syscall_nr.
> Architectures where the same syscall may use a different syscall number
> for compat tasks need to define ARCH_COMPAT_SYSCALL_NUMBERS_OVERLAP and
> define a method arch_trace_is_compat_syscall(struct pt_regs*) that tells
> if a current task is a compat one.
> For architectures that define ARCH_COMPAT_SYSCALL_NUMBERS_OVERLAP the
> number of trace event files is doubled and all syscall trace events are
> identified by the syscall number offset by NR_syscalls.
>
> Note that as this patch series is posted as an RFC, this currently only
> includes arch updates for MIPS and x86 (and has only been tested on
> MIPS and x86_64). I will work on updating other arch trees after this
> solution is reviewed.
I bet you didn't test x32 -- see below :)
>
> Signed-off-by: Marcin Nowakowski <marcin.nowakowski@xxxxxxxxxx>
>
> ---
> arch/mips/kernel/ftrace.c | 4 +-
> arch/x86/include/asm/ftrace.h | 10 +---
> arch/x86/kernel/ftrace.c | 14 ++++++
> include/linux/ftrace.h | 2 +-
> kernel/trace/trace.h | 11 +++-
> kernel/trace/trace_syscalls.c | 113 +++++++++++++++++++++++++-----------------
> 6 files changed, 94 insertions(+), 60 deletions(-)
>
> diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
> index 937c54b..e150cf6 100644
> --- a/arch/mips/kernel/ftrace.c
> +++ b/arch/mips/kernel/ftrace.c
> @@ -412,7 +412,7 @@ out:
> #ifdef CONFIG_FTRACE_SYSCALLS
>
> #ifdef CONFIG_32BIT
> -unsigned long __init arch_syscall_addr(int nr)
> +unsigned long __init arch_syscall_addr(int nr, int compat)
> {
> return (unsigned long)sys_call_table[nr - __NR_O32_Linux];
> }
> @@ -420,7 +420,7 @@ unsigned long __init arch_syscall_addr(int nr)
>
> #ifdef CONFIG_64BIT
>
> -unsigned long __init arch_syscall_addr(int nr)
> +unsigned long __init arch_syscall_addr(int nr, int compat)
bool compat?
> {
> #ifdef CONFIG_MIPS32_N32
> if (nr >= __NR_N32_Linux && nr <= __NR_N32_Linux + __NR_N32_Linux_syscalls)
> diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
> index a4820d4..a24a21c 100644
> --- a/arch/x86/include/asm/ftrace.h
> +++ b/arch/x86/include/asm/ftrace.h
> @@ -47,15 +47,7 @@ int ftrace_int3_handler(struct pt_regs *regs);
> #if defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_IA32_EMULATION)
> #include <asm/compat.h>
>
> -/*
> - * Because ia32 syscalls do not map to x86_64 syscall numbers
> - * this screws up the trace output when tracing a ia32 task.
> - * Instead of reporting bogus syscalls, just do not trace them.
> - *
> - * If the user really wants these, then they should use the
> - * raw syscall tracepoints with filtering.
> - */
> -#define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS 1
> +#define ARCH_COMPAT_SYSCALL_NUMBERS_OVERLAP 1
> static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
> {
> if (in_compat_syscall())
This isn't your fault obviously, but shouldn't that be in_ia32_syscall()?
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