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Follow GNU C Library from c579f48edba88380635ab98cb612030e3ed8691e
and remove the PID caching. These simplifies the architecture specific
assembly code.
The run of the test suite found no regressions, it even solves
some of the test failures for x86/x86_64/sparc.
Reviewed-by: Max Filippov <jcmvbkbc@gmail.com>
Reviewed-by: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Acked-by: Matthew Fortune <Matthew.Fortune@imgtec.com>
Acked-by: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
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This change was inspired by similar change in glibc:
https://sourceware.org/git/?p=glibc.git;a=commit;h=0cb313f7cb0e418b3d56f3a2ac69790522ab825d
Current Linux kernel requires CLONE_VM to be set with CLONE_THREAD
otherwise returning -EINVAL, see man clone2. This means we don't need
to check for both CLONE_THREAD and CLONE_VM instead we may simplify
code a lot and just check 1 bit (CLONE_THREAD).
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
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For thread group case (CLONE_THREAD), the cached PID of new process/thread
need not be reset. The old logic to decide that was flawed as it would be
true only for exact combination of CLONE_THREAD + _VM, but would fail for
CLONE_THREAD + _VM + _xyz.
More detailed tear-down of current and new code below.
Current implementation is:
--------------------->8--------------------
; r12 contains clone flags
mov_s r2, CLONE_THREAD_N_VM; r2 contains bit mask
and_s r2, r2, r12 ; r2 contains bit mask AND clone flags
; but r12 still contains the same flags
brne r2, r12, .Lgo_thread ; here we compare modified mask with
; flags as they were and skip pthread TID/PID
; setup if r2 != r12 which happens all
; the time except clone flags were
; exactly CLONE_THREAD | CLONE_VM
--------------------->8--------------------
New implementation is:
--------------------->8--------------------
; r12 contains clone flags
mov_s r2, CLONE_THREAD_N_VM; r2 contains bit mask
and_s r12, r12, r2 ; r12 contains clone flags AND bit mask
; i.e. we did mask all flags except
; CLONE_THREAD and CLONE_VM
breq r2, r12, .Lgo_thread ; here we compare masked flags with
; target mask and if they match we skip
; pthread TID/PID setup
--------------------->8--------------------
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
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Caught by tst-getpid1 test from uClibc's test-suite.
It looks like original implementation was not correct.
The code in question is supposed to recover PID of the new
thread. And by no means that could happen with clone() syscall
while getpid() does exactly this.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Reported-by: Eugeniy Paltsev <paltsev@synopsys.com>
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Typically kernel would set the TP register of newly created thread in
clone syscall with CLONE_SETTLS.
However this implies that:
* kernel knows of the exact TP register (which is already different for
ARCompact and ARCv2) and is a detail which becomes part of the ABI
* kernel also needs to handle the unlikely but possible case of !TLS
userspace (e.g. Android libc) case where TP reg is not reserved and
thus need not be mucked with (using ELF personality based detection)
It is better to confine this detail to userspace runtime and set TP reg
right after clone syscall returns.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
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Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
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This showed up due to longstanding test/unistd/clone failure where post
clone, the callback was not exiting and rather falling thru in into main
program.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
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For this port, I would like to give due credit to:
- Folks from Codito technologies (Sameer, Amit, Kanika, Ramana,...)
who did the very first port
- ARC UK from 2007-2009 (Joern, Irfan, Khurram, Phil...
- Late Brendan Kehoe (may he RIP)
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
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