similar to: [PATCH] x86/paravirt: convert simple paravirt functions to asm

All functions referenced via __PV_IS_CALLEE_SAVE() need to be assembler functions, as those functions calls are hidden from gcc. In case the kernel is compiled with "-fzero-call-used-regs" the compiler will clobber caller-saved registers at the end of C functions, which will result in unexpectedly zeroed registers at the call site of the related paravirt functions. Replace the C

This is a small series getting rid of paravirt patching by switching completely to alternative patching for the same functionality. The basic idea is to add the capability to switch from indirect to direct calls via a special alternative patching option. This removes _some_ of the paravirt macro maze, but most of it needs to stay due to the need of hiding the call instructions from the compiler

This is a small series getting rid of paravirt patching by switching completely to alternative patching for the same functionality. The basic idea is to add the capability to switch from indirect to direct calls via a special alternative patching option. This removes _some_ of the paravirt macro maze, but most of it needs to stay due to the need of hiding the call instructions from the compiler

On Wed, Jul 15, 2020 at 11:13:37AM +0200, Joerg Roedel wrote: > On Wed, Jul 15, 2020 at 10:47:52AM +0200, Peter Zijlstra wrote: > > On Tue, Jul 14, 2020 at 02:09:05PM +0200, Joerg Roedel wrote: > > > > > @@ -1028,6 +1036,16 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication) > > > struct ghcb *ghcb; > > > > > >

On Wed, Jul 15, 2020 at 11:13:37AM +0200, Joerg Roedel wrote: > On Wed, Jul 15, 2020 at 10:47:52AM +0200, Peter Zijlstra wrote: > > On Tue, Jul 14, 2020 at 02:09:05PM +0200, Joerg Roedel wrote: > > > > > @@ -1028,6 +1036,16 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication) > > > struct ghcb *ghcb; > > > > > >

On 09.03.23 14:39, Borislav Petkov wrote: > On Wed, Mar 08, 2023 at 04:42:10PM +0100, Juergen Gross wrote: >> All functions referenced via __PV_IS_CALLEE_SAVE() need to be assembler >> functions, as those functions calls are hidden from gcc. In case the >> kernel is compiled with "-fzero-call-used-regs" the compiler will >> clobber caller-saved registers at the

On Tue, Jul 14, 2020 at 02:08:47PM +0200, Joerg Roedel wrote: > @@ -489,6 +490,9 @@ DEFINE_IDTENTRY_RAW(exc_nmi) > this_cpu_write(nmi_cr2, read_cr2()); > nmi_restart: > > + /* Needs to happen before DR7 is accessed */ > + sev_es_ist_enter(regs); > + > this_cpu_write(nmi_dr7, local_db_save()); > > nmi_enter(); > @@ -502,6 +506,8 @@

On Tue, Jul 14, 2020 at 02:08:47PM +0200, Joerg Roedel wrote: > @@ -489,6 +490,9 @@ DEFINE_IDTENTRY_RAW(exc_nmi) > this_cpu_write(nmi_cr2, read_cr2()); > nmi_restart: > > + /* Needs to happen before DR7 is accessed */ > + sev_es_ist_enter(regs); > + > this_cpu_write(nmi_dr7, local_db_save()); > > nmi_enter(); > @@ -502,6 +506,8 @@

On Wed, Jul 15, 2020 at 12:08:08PM +0200, Joerg Roedel wrote: > On Wed, Jul 15, 2020 at 11:51:36AM +0200, Peter Zijlstra wrote: > > On Wed, Jul 15, 2020 at 11:13:37AM +0200, Joerg Roedel wrote: > > > Then my understanding of intrumentation_begin/end() is wrong, I thought > > > that the kernel will forbid setting breakpoints before > > > instrumentation_begin(),

On Thu, Feb 27, 2020 at 04:00:45PM -0800, Thomas Garnier wrote: > Minor changes based on feedback and rebase from v10. > > Splitting the previous serie in two. This part contains assembly code > changes required for PIE but without any direct dependencies with the > rest of the patchset. > > Note: Using objtool to detect non-compliant PIE relocations is not yet > possible

On Thu, Feb 27, 2020 at 04:00:45PM -0800, Thomas Garnier wrote: > Minor changes based on feedback and rebase from v10. > > Splitting the previous serie in two. This part contains assembly code > changes required for PIE but without any direct dependencies with the > rest of the patchset. > > Note: Using objtool to detect non-compliant PIE relocations is not yet > possible

On Tue, Jun 23, 2020 at 03:59:16PM +0200, Peter Zijlstra wrote: > So basically when your exception frame points to your own IST, you die. > That sounds like something we should have in generic IST code. Something like this... #DF already dies and NMI is 'magic' --- arch/x86/entry/common.c | 7 +++++++ arch/x86/include/asm/idtentry.h | 12 +++++++++++- 2 files changed, 18

On Tue, Jun 23, 2020 at 02:52:01PM +0200, Peter Zijlstra wrote: > On Tue, Jun 23, 2020 at 02:04:33PM +0200, Joerg Roedel wrote: > > No, the recursion check is fine, because overwriting an already used IST > > stack doesn't matter (as long as it can be detected) if we are going to > > panic anyway. It doesn't matter because the kernel will not leave the > >

On Tue, Jun 23, 2020 at 04:59:14PM +0200, Joerg Roedel wrote: > On Tue, Jun 23, 2020 at 04:53:44PM +0200, Peter Zijlstra wrote: > > +noinstr void idtentry_validate_ist(struct pt_regs *regs) > > +{ > > + if ((regs->sp & ~(EXCEPTION_STKSZ-1)) == > > + (_RET_IP_ & ~(EXCEPTION_STKSZ-1))) > > + die("IST stack recursion", regs, 0); > > +}

On Tue, Jul 14, 2020 at 02:09:05PM +0200, Joerg Roedel wrote: > @@ -1028,6 +1036,16 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication) > struct ghcb *ghcb; > > lockdep_assert_irqs_disabled(); > + > + /* > + * #DB is special and needs to be handled outside of the intrumentation_begin()/end(). > + * Otherwise the #VC handler could be raised recursivly. > +

On Tue, Jul 14, 2020 at 02:09:05PM +0200, Joerg Roedel wrote: > @@ -1028,6 +1036,16 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication) > struct ghcb *ghcb; > > lockdep_assert_irqs_disabled(); > + > + /* > + * #DB is special and needs to be handled outside of the intrumentation_begin()/end(). > + * Otherwise the #VC handler could be raised recursivly. > +

On Wed, Aug 05, 2020 at 03:26:29PM +0200, Marco Elver wrote: > Add missing noinstr to arch_local*() helpers, as they may be called from > noinstr code. > > On a KCSAN config with CONFIG_PARAVIRT=y, syzbot stumbled across corrupt Cute, so I've been working on adding objtool support for this a little: https://lkml.kernel.org/r/20200803143231.GE2674 at

Fantastic! Thanks for all of the input! I'll be considering all of it going forward. The plan right now is just to worry about ELF executables and nothing else. I'm very sympathetic to the "llvm-objtool" change. If everyone is cool with it I'll change the name in the next CL to "llvm-objtool". To start out I implemented a very basic ELF64LE specific bit of code.

On Tue, Aug 11, 2020 at 11:20:54AM +0200, peterz at infradead.org wrote: > On Tue, Aug 11, 2020 at 10:38:50AM +0200, J?rgen Gro? wrote: > > In case you don't want to do it I can send the patch for the Xen > > variants. > > I might've opened a whole new can of worms here. I'm not sure we > can/want to fix the entire fallout this release :/ > > Let me

On Tue, Aug 11, 2020 at 11:20:54AM +0200, peterz at infradead.org wrote: > On Tue, Aug 11, 2020 at 10:38:50AM +0200, J?rgen Gro? wrote: > > In case you don't want to do it I can send the patch for the Xen > > variants. > > I might've opened a whole new can of worms here. I'm not sure we > can/want to fix the entire fallout this release :/ > > Let me