Messages in this thread Patch in this message | | | Subject | [RFC][PATCH 2/8] x86/fpu: hook up PKRU into signal user ABIs | From | Dave Hansen <> | Date | Tue, 22 Jun 2021 15:24:59 -0700 |
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From: Dave Hansen <dave.hansen@linux.intel.com>
One nice thing about having PKRU be XSAVE-managed is that it gets naturally exposed into the XSAVE-using ABIs. Now that XSAVE will not be used to manage PKRU, these ABIs need to be manually enabled to deal with PKRU.
For signals (the restore_hwregs_from_user() path), it's quite straightforward. restore_hwregs_from_user() will update PKRU in from the user signal buffer. Ensure that PKRU is shuffled into the thread storage.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: x86@kernel.org Cc: Andy Lutomirski <luto@kernel.org> ---
b/arch/x86/kernel/fpu/signal.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff -puN arch/x86/kernel/fpu/signal.c~fpu-sig-stash-pkru arch/x86/kernel/fpu/signal.c --- a/arch/x86/kernel/fpu/signal.c~fpu-sig-stash-pkru 2021-06-22 14:49:07.899051760 -0700 +++ b/arch/x86/kernel/fpu/signal.c 2021-06-22 14:49:07.903051760 -0700 @@ -233,6 +233,13 @@ static int restore_hwregs_from_user(void if (!ret && unlikely(init_bv)) os_xrstor(&init_fpstate.xsave, init_bv); + + /* + * PKRU may have been modified by XRSTOR, + * save the possibly updated value: + */ + current->thread.pkru = read_pkru(); + return ret; } else if (use_fxsr()) { return fxrstor_from_user_sigframe(buf); _
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