| Message ID | 20160426011431.GA3752@brightrain.aerifal.cx (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/arch/sh/include/uapi/asm/sigcontext.h b/arch/sh/include/uapi/asm/sigcontext.h index 8ce1435..faa5d08 100644 --- a/arch/sh/include/uapi/asm/sigcontext.h +++ b/arch/sh/include/uapi/asm/sigcontext.h @@ -25,8 +25,6 @@ struct sigcontext { unsigned long sc_mach; unsigned long sc_macl; -#if defined(__SH4__) || defined(CONFIG_CPU_SH4) || \ - defined(__SH2A__) || defined(CONFIG_CPU_SH2A) /* FPU registers */ unsigned long sc_fpregs[16]; unsigned long sc_xfpregs[16]; @@ -34,7 +32,6 @@ struct sigcontext { unsigned int sc_fpul; unsigned int sc_ownedfp; #endif -#endif }; #endif /* __ASM_SH_SIGCONTEXT_H */
Up until now, the SH version of the sigcontext structure, and thus mcontext_t/ucontext_t, varied depending on the cpu model the kernel was built to run on. SH-4 (including SH-4A) and SH-2A used the form with space for FPU registers, and everything else used a form that omitted them. From a userspace perspective, however, the structure layout must be fixed for a given ABI. Traditionally glibc and uClibc used the form with space for FPU registers only when __SH4__ (which implies FPU; __SH4_NOFPU__ is the predefined macro for SH-4 but with no-FPU ABI) was defined. As a result: - SH-4 no-FPU programs never matched kernel sigcontext. - SH-3 programs did not match kernel sigcontext if run on SH-4, despite an apparent intent that they be compatible. - SH-2 and SH-2A programs (using uClibc) did not match kernel sigcontext if run on SH-2A. The mismatch might seem inconsequential because it occurs at the end of the sigcontext structure, but sigcontext is embedded as uc_mcontext in ucontext_t, where it is followed by uc_sigmask, an important member for signal handlers to have access to. In particular, access to uc_sigmask is necessary for a correct implementation of thread cancellation. It would be possible to retain support for both sigcontext ABIs via a personality mechanism, but since many configurations were already broken and nobody noticed, and since there are very few if any users of legacy no-FPU models anymore, I have opted to just remove the variation and always include space for the FPU registers in sigcontext. This was proposed and discussed on a thread "SH sigcontext ABI is broken" cross-posted to linux-sh, libc-alpha, and musl libc lists in June 2015, and no objections were raised. Signed-off-by: Rich Felker <dalias@libc.org> --- This was discussed last year and there were no objections I'm aware of. I plan to include this in the official patch series for J2 support and push it in the next (4.7) merge window. Please speak now if you have a strong reason for wanting this handled differently. arch/sh/include/uapi/asm/sigcontext.h | 3 --- 1 file changed, 3 deletions(-)