On 23.05.2018 16:49, Michael Kerrisk (man-pages) wrote:
> Hello Helge,
>
> On 22 May 2018 at 15:14, Helge Deller <deller@xxxxxx> wrote:
>> The parisc gateway page currently only exports 3 functions:
>> The lws_entry for CAS operations (at 0xb0), the set_thread_pointer
>> function for usage in glibc (at 0xe0) and the linux syscall entry (at
>> 0x100).
>>
>> All other symbols in the manpage are internal labels and shouldn't be
>> used directly by userspace or glibc, so drop them from the man page
>> documentation.
>
> Can I clarify a point here. You say they are "internal labels that
> shouldn't be used".
Correct.
> This seems a little contradictory. Am I correct to
> understand that what you mean is that those symbols are actually
> visible but should be used?
... those symbols are actually visible but should NOT be used?
-> Yes.
The code flow is:
Userspace jumps to 0xb0 which is symbol "lws_entry".
lws_entry then runs across lws_start, then e.g. to lws_compare_and_swap and
returns to userspace via lws_exit.
All symbols beside lws_entry should not be visible to userspace and should not be
called directly by userspace.
Thus, those symbols should not be listed in the man page either.
Ideally I should mark those symbols as local symbols in the
kernel source code in a future patch....
> If yes, maybe some words need to be added
> to the text to bring this point across.
I'm fine with any better wording.
Helge
>> Signed-off-by: Helge Deller <deller@xxxxxx>
>>
>> diff --git a/man7/vdso.7 b/man7/vdso.7
>> index 6eec351e5..6ee64ed4b 100644
>> --- a/man7/vdso.7
>> +++ b/man7/vdso.7
>> @@ -322,7 +322,7 @@ set_tid_address
>> .SS parisc (hppa) functions
>> .\" See linux/arch/parisc/kernel/syscall.S
>> .\" See linux/Documentation/parisc/registers
>> -The parisc port has a code page full of utility functions
>> +The parisc port has a code page with utility functions
>> called a gateway page.
>> Rather than use the normal ELF auxiliary vector approach,
>> it passes the address of
>> @@ -344,21 +344,9 @@ for example:
>> l l.
>> offset function
>> _
>> -00b0 lws_entry
>> -00e0 set_thread_pointer
>> +00b0 lws_entry (CAS operations)
>> +00e0 set_thread_pointer (used by glibc)
>> 0100 linux_gateway_entry (syscall)
>> -0268 syscall_nosys
>> -0274 tracesys
>> -0324 tracesys_next
>> -0368 tracesys_exit
>> -03a0 tracesys_sigexit
>> -03b8 lws_start
>> -03dc lws_exit_nosys
>> -03e0 lws_exit
>> -03e4 lws_compare_and_swap64
>> -03e8 lws_compare_and_swap
>> -0404 cas_wouldblock
>> -0410 cas_action
>> .TE
>> .if t \{\
>> .in
>
>
>
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