Tony Lindgren wrote: > __kuser_get_tls: @ 0xffff0fe0 > - > -#if !defined(CONFIG_HAS_TLS_REG) && !defined(CONFIG_TLS_REG_EMUL) > - ldr r0, [pc, #(16 - 8)] @ TLS stored at 0xffff0ff0 > -#else > - mrc p15, 0, r0, c13, c0, 3 @ read TLS register > -#endif > + ldr r0, [pc, #(20 - 8)] @ software TLS set in > 0xffff0ff4? > + cmp r0, #0 @ hardware TLS if flag not set > + mrceq p15, 0, r0, c13, c0, 3 @ read hardware TLS register > + ldrne r0, [pc, #(12 - 8)] @ software TLS val at 0xffff0ff8 > usr_ret lr > - > - .rep 5 > - .word 0 @ pad up to __kuser_helper_version > - .endr > + .word 0 @ non-zero for software TLS > + .word 0 @ software TLS value
It'd be nice not to waste instructions checking for HWCAP_TLS on archs which definitely don't have it. I guess it doesn't matter elsewhere; I'd expect this to be a warm path for some programs making extensive use of TLS (I haven't measured though). As it's only a single instruction, and the code is in a writable page already (copied at init), how about just patching the instruction when ELF_HWCAP is set? -- Jamie -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
