Re: [PATCH v7 23/26] x86/traps: Fixup general protection faults caused by UMIP
I am sorry Boris, I also missed this feedback. On Fri, 2017-06-09 at 15:02 +0200, Borislav Petkov wrote: > On Fri, May 05, 2017 at 11:17:21AM -0700, Ricardo Neri wrote: > > If the User-Mode Instruction Prevention CPU feature is available and > > enabled, a general protection fault will be issued if the instructions > > sgdt, sldt, sidt, str or smsw are executed from user-mode context > > (CPL > 0). If the fault was caused by any of the instructions protected > > by UMIP, fixup_umip_exception will emulate dummy results for these > > Please end function names with parentheses. I have audited my commit messages to remove all instances of this error. > > > instructions. If emulation is successful, the result is passed to the > > user space program and no SIGSEGV signal is emitted. > > > > Please note that fixup_umip_exception also caters for the case when > > the fault originated while running in virtual-8086 mode. > > > > Cc: Andy Lutomirski > > Cc: Andrew Morton > > Cc: H. Peter Anvin > > Cc: Borislav Petkov > > Cc: Brian Gerst > > Cc: Chen Yucong > > Cc: Chris Metcalf > > Cc: Dave Hansen > > Cc: Fenghua Yu > > Cc: Huang Rui > > Cc: Jiri Slaby > > Cc: Jonathan Corbet > > Cc: Michael S. Tsirkin > > Cc: Paul Gortmaker > > Cc: Peter Zijlstra > > Cc: Ravi V. Shankar > > Cc: Shuah Khan > > Cc: Vlastimil Babka > > Cc: Tony Luck > > Cc: Paolo Bonzini > > Cc: Liang Z. Li > > Cc: Alexandre Julliard > > Cc: Stas Sergeev > > Cc: x...@kernel.org > > Cc: linux-msdos@vger.kernel.org > > Reviewed-by: Andy Lutomirski > > Signed-off-by: Ricardo Neri > > --- > > arch/x86/kernel/traps.c | 4 > > 1 file changed, 4 insertions(+) > > > > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > > index 3995d3a..cec548d 100644 > > --- a/arch/x86/kernel/traps.c > > +++ b/arch/x86/kernel/traps.c > > @@ -65,6 +65,7 @@ > > #include > > #include > > #include > > +#include > > > > #ifdef CONFIG_X86_64 > > #include > > @@ -526,6 +527,9 @@ do_general_protection(struct pt_regs *regs, long > > error_code) > > RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); > > cond_local_irq_enable(regs); > > > > Almost definitely: > > if (static_cpu_has(X86_FEATURE_UMIP)) { > if (... I will make this update. > > > + if (user_mode(regs) && fixup_umip_exception(regs)) > > + return; > > We don't want to punish !UMIP machines. I will add this check. Thanks and BR, Ricardo -- To unsubscribe from this list: send the line "unsubscribe linux-msdos" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v7 23/26] x86/traps: Fixup general protection faults caused by UMIP
On Fri, May 05, 2017 at 11:17:21AM -0700, Ricardo Neri wrote: > If the User-Mode Instruction Prevention CPU feature is available and > enabled, a general protection fault will be issued if the instructions > sgdt, sldt, sidt, str or smsw are executed from user-mode context > (CPL > 0). If the fault was caused by any of the instructions protected > by UMIP, fixup_umip_exception will emulate dummy results for these Please end function names with parentheses. > instructions. If emulation is successful, the result is passed to the > user space program and no SIGSEGV signal is emitted. > > Please note that fixup_umip_exception also caters for the case when > the fault originated while running in virtual-8086 mode. > > Cc: Andy Lutomirski > Cc: Andrew Morton > Cc: H. Peter Anvin > Cc: Borislav Petkov > Cc: Brian Gerst > Cc: Chen Yucong > Cc: Chris Metcalf > Cc: Dave Hansen > Cc: Fenghua Yu > Cc: Huang Rui > Cc: Jiri Slaby > Cc: Jonathan Corbet > Cc: Michael S. Tsirkin > Cc: Paul Gortmaker > Cc: Peter Zijlstra > Cc: Ravi V. Shankar > Cc: Shuah Khan > Cc: Vlastimil Babka > Cc: Tony Luck > Cc: Paolo Bonzini > Cc: Liang Z. Li > Cc: Alexandre Julliard > Cc: Stas Sergeev > Cc: x...@kernel.org > Cc: linux-msdos@vger.kernel.org > Reviewed-by: Andy Lutomirski > Signed-off-by: Ricardo Neri > --- > arch/x86/kernel/traps.c | 4 > 1 file changed, 4 insertions(+) > > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > index 3995d3a..cec548d 100644 > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -65,6 +65,7 @@ > #include > #include > #include > +#include > > #ifdef CONFIG_X86_64 > #include > @@ -526,6 +527,9 @@ do_general_protection(struct pt_regs *regs, long > error_code) > RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); > cond_local_irq_enable(regs); > Almost definitely: if (static_cpu_has(X86_FEATURE_UMIP)) { if (... > + if (user_mode(regs) && fixup_umip_exception(regs)) > + return; We don't want to punish !UMIP machines. -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) -- -- To unsubscribe from this list: send the line "unsubscribe linux-msdos" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH v7 23/26] x86/traps: Fixup general protection faults caused by UMIP
If the User-Mode Instruction Prevention CPU feature is available and enabled, a general protection fault will be issued if the instructions sgdt, sldt, sidt, str or smsw are executed from user-mode context (CPL > 0). If the fault was caused by any of the instructions protected by UMIP, fixup_umip_exception will emulate dummy results for these instructions. If emulation is successful, the result is passed to the user space program and no SIGSEGV signal is emitted. Please note that fixup_umip_exception also caters for the case when the fault originated while running in virtual-8086 mode. Cc: Andy Lutomirski Cc: Andrew Morton Cc: H. Peter Anvin Cc: Borislav Petkov Cc: Brian Gerst Cc: Chen Yucong Cc: Chris Metcalf Cc: Dave Hansen Cc: Fenghua Yu Cc: Huang Rui Cc: Jiri Slaby Cc: Jonathan Corbet Cc: Michael S. Tsirkin Cc: Paul Gortmaker Cc: Peter Zijlstra Cc: Ravi V. Shankar Cc: Shuah Khan Cc: Vlastimil Babka Cc: Tony Luck Cc: Paolo Bonzini Cc: Liang Z. Li Cc: Alexandre Julliard Cc: Stas Sergeev Cc: x...@kernel.org Cc: linux-msdos@vger.kernel.org Reviewed-by: Andy Lutomirski Signed-off-by: Ricardo Neri --- arch/x86/kernel/traps.c | 4 1 file changed, 4 insertions(+) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 3995d3a..cec548d 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -65,6 +65,7 @@ #include #include #include +#include #ifdef CONFIG_X86_64 #include @@ -526,6 +527,9 @@ do_general_protection(struct pt_regs *regs, long error_code) RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); cond_local_irq_enable(regs); + if (user_mode(regs) && fixup_umip_exception(regs)) + return; + if (v8086_mode(regs)) { local_irq_enable(); handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code); -- 2.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-msdos" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html