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Re: manual SyS_foo management is unnecessary?
- From: Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>
- To: Josh Stone <jistone at redhat dot com>
- Cc: systemtap at sourceware dot org
- Date: Tue, 15 Jun 2010 10:49:06 +0530
- Subject: Re: manual SyS_foo management is unnecessary?
- References: <4C168896.7010804@redhat.com>
- Reply-to: ananth at in dot ibm dot com
On Mon, Jun 14, 2010 at 12:52:54PM -0700, Josh Stone wrote:
...
> probe nd_syscall.open = kprobe.function("compat_sys_open") ?,
> kprobe.function("sys32_open") ?,
> kprobe.function("SyS_open") ?,
> kprobe.function("sys_open") ?
>
> The kprobe.function is resolved only at runtime, where kprobes uses
> kallsyms to map the symbol name to an address. It turns out, at least
> on recent kernels, that kallsyms also resolves aliased names. So again
> SyS_open and sys_open create duplicate probe addresses.
For the normal case (kernel.function) case, when SYSCALL_WRAPPERS were
introduced, every one of the syscall tests would fail with 'no match for
probe point sys_open' and the like. This was because the sys_ variants
would be inlined and stap wouldn't find them. Has this changed?
Ananth