Messages in this thread | | | Date | Sat, 3 Nov 2018 19:07:36 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [Patch v4 03/18] x86/speculation: Reorganize cpu_show_common() |
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Tim,
On Tue, 30 Oct 2018, Tim Chen wrote: > Extract the logic to show IBPB, STIBP usages in cpu_show_common() > into helper functions. > > Later patches will add other userspace Spectre v2 mitigation modes. > This patch makes it easy to show IBPB and STIBP > usage scenario according to the mitigation mode.
First of all, I asked you before to do:
# git grep 'This patch' Documentation/process
This leads you to:
"Describe your changes in imperative mood, e.g. "make xyzzy do frotz" instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy to do frotz", as if you are giving orders to the codebase to change its behaviour."
Documentation is there for a reason.
Aside of that, I'd really have a hard time to figure out what you are trying to say, if I didn't have the context already. Change logs need to make sense on their own. So something like this:
The Spectre V2 printout in cpu_show_common() handles conditionals for the various mitigation methods directly in the sprintf() argument list. That's hard to read and will become unreadable if more complex decisions need to be made for a particular method.
Move the conditionals for STIBP and IBPB string selection into helper functions, so they can be extended later on.
follows the obvious ordering for change logs:
1) Describe context and problem
2) Describe the solution
and is understandable without needing to know about the context in which this change was developed.
Hmm? This is a suggestion, feel free to rewrite it in you own words. The same applies to other change logs as well. I won't comment on those.
> static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr, > char *buf, unsigned int bug) > { > @@ -872,9 +888,8 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr > > case X86_BUG_SPECTRE_V2: > return sprintf(buf, "%s%s%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled], > - boot_cpu_has(X86_FEATURE_USE_IBPB) ? ", IBPB" : "", > boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "", > - (x86_spec_ctrl_base & SPEC_CTRL_STIBP) ? ", STIBP" : "", > + ibpb_state(), stibp_state(), > boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "", > spectre_v2_module_string());
Any particular reason for changing the output ordering here? If yes, then the changelog should mention it. If no, why?
Thanks,
tglx
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