On Wed, Jun 18, 2014 at 03:00:46PM +0100, Paul Burton wrote:
> This reverts commit eec43a224cf1 "MIPS: Save/restore MSA context around
> signals" and the MSA parts of ca750649e08c "MIPS: kernel: signal:
> Prevent save/restore FPU context in user memory" (the restore path of
> which appears incorrect anyway...).
>
> The reverted patch took care not to break compatibility with userland
> users of struct sigcontext, but inadvertantly changed the offset of the
> uc_sigmask field of struct ucontext. Thus Linux v3.15 breaks the
> userland ABI. The MSA context will need to be saved via some other
> opt-in mechanism, but for now revert the change to reduce the fallout.
>
> This will have minimal impact upon use of MSA since the only supported
> CPU which includes it (the P5600) is 32-bit and therefore requires that
> the experimental CONFIG_MIPS_O32_FP64_SUPPORT Kconfig option be selected
> before the kernel will set FR=1 for a task, a requirement for MSA use.
> Thus the users of MSA are limited to known small groups of people & this
> patch won't be breaking any previously working MSA-using userland
> outside of experimental settings.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Joseph S. Myers <joseph@xxxxxxxxxxxxxxxx>
> Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
> ---
> Ralf: if this can get into mainline ASAP so it can hit the 3.15 stable
> branch too that would be great. Sorry for this!
I tried to apply this to my fixes branch which is 3.16-rc1-based but
I'm getting rejects:
--- arch/mips/kernel/asm-offsets.c
+++ arch/mips/kernel/asm-offsets.c
@@ -296,8 +296,6 @@
OFFSET(SC_LO2, sigcontext, sc_lo2);
OFFSET(SC_HI3, sigcontext, sc_hi3);
OFFSET(SC_LO3, sigcontext, sc_lo3);
- OFFSET(SC_MSAREGS, sigcontext, sc_msaregs);
- OFFSET(SC_MSA_CSR, sigcontext, sc_msa_csr);
BLANK();
}
#endif
@@ -312,8 +310,6 @@
OFFSET(SC_MDLO, sigcontext, sc_mdlo);
OFFSET(SC_PC, sigcontext, sc_pc);
OFFSET(SC_FPC_CSR, sigcontext, sc_fpc_csr);
- OFFSET(SC_MSAREGS, sigcontext, sc_msaregs);
- OFFSET(SC_MSA_CSR, sigcontext, sc_msa_csr);
BLANK();
}
#endif
@@ -325,8 +321,6 @@
OFFSET(SC32_FPREGS, sigcontext32, sc_fpregs);
OFFSET(SC32_FPC_CSR, sigcontext32, sc_fpc_csr);
OFFSET(SC32_FPC_EIR, sigcontext32, sc_fpc_eir);
- OFFSET(SC32_MSAREGS, sigcontext32, sc_msaregs);
- OFFSET(SC32_MSA_CSR, sigcontext32, sc_msa_csr);
BLANK();
}
#endif
This is rejecting because the upstream asm-offsets.c doesn't contain
the SC_MSA_CSR / SC32_MSA_CSR lines. Also hunk2 of r4k_fpu.S is
rejecting.
I've fixed the rejects and applied this as c0a098f1 to upstream-sfr
but you may want to test this and resubmit it for -stable.
Cheers,
Ralf
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