From: Madhavan T. Venkataraman <redacted>

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 <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <redacted>
Cc: Madhavan T. Venkataraman <redacted>
Cc: Mickaël Salaün <mic@digikod.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Thomas Gleixner <redacted>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <redacted>
Signed-off-by: Madhavan T. Venkataraman <redacted>
---

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;
 }