On Sun, Nov 12, 2023 at 09:23:24PM -0500, Mickaël Salaün wrote: > From: Madhavan T. Venkataraman <madve...@linux.microsoft.com> > > X86 uses a function called __text_poke() to modify executable code. This > patching function is used by many features such as KProbes and FTrace. > > Update the permissions counters for the text page so that write > permissions can be temporarily established in the EPT to modify the > instructions in that page. > > Cc: Borislav Petkov <b...@alien8.de> > Cc: Dave Hansen <dave.han...@linux.intel.com> > Cc: H. Peter Anvin <h...@zytor.com> > Cc: Ingo Molnar <mi...@redhat.com> > Cc: Kees Cook <keesc...@chromium.org> > Cc: Madhavan T. Venkataraman <madve...@linux.microsoft.com> > Cc: Mickaël Salaün <m...@digikod.net> > Cc: Paolo Bonzini <pbonz...@redhat.com> > Cc: Sean Christopherson <sea...@google.com> > Cc: Thomas Gleixner <t...@linutronix.de> > Cc: Vitaly Kuznetsov <vkuzn...@redhat.com> > Cc: Wanpeng Li <wanpen...@tencent.com> > Signed-off-by: Madhavan T. Venkataraman <madve...@linux.microsoft.com> > --- > > Changes since v1: > * New patch > --- > arch/x86/kernel/alternative.c | 5 ++++ > arch/x86/mm/heki.c | 49 +++++++++++++++++++++++++++++++++++ > include/linux/heki.h | 14 ++++++++++ > 3 files changed, 68 insertions(+) > > diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c > index 517ee01503be..64fd8757ba5c 100644 > --- a/arch/x86/kernel/alternative.c > +++ b/arch/x86/kernel/alternative.c > @@ -18,6 +18,7 @@ > #include <linux/mmu_context.h> > #include <linux/bsearch.h> > #include <linux/sync_core.h> > +#include <linux/heki.h> > #include <asm/text-patching.h> > #include <asm/alternative.h> > #include <asm/sections.h> > @@ -1801,6 +1802,7 @@ static void *__text_poke(text_poke_f func, void *addr, > const void *src, size_t l > */ > pgprot = __pgprot(pgprot_val(PAGE_KERNEL) & ~_PAGE_GLOBAL); > > + heki_text_poke_start(pages, cross_page_boundary ? 2 : 1, pgprot); > /* > * The lock is not really needed, but this allows to avoid open-coding. > */ > @@ -1865,7 +1867,10 @@ static void *__text_poke(text_poke_f func, void *addr, > const void *src, size_t l > } > > local_irq_restore(flags); > + > pte_unmap_unlock(ptep, ptl); > + heki_text_poke_end(pages, cross_page_boundary ? 2 : 1, pgprot); > + > return addr; > }
This makes no sense, we already use a custom CR3 with userspace alias for the actual pages to write to, why are you then frobbing permissions on that *again* ?
