linux-kernel - [RFC PATCH 41/56] static_call: Add update_all_static

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Message-ID: <20251013143444.3999-42-david.kaplan@amd.com>
Date: Mon, 13 Oct 2025 09:34:29 -0500
From: David Kaplan <david.kaplan@....com>
To: Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>,
	Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>,
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, Ingo Molnar
	<mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, "H . Peter Anvin" <hpa@...or.com>
CC: Alexander Graf <graf@...zon.com>, Boris Ostrovsky
	<boris.ostrovsky@...cle.com>, <linux-kernel@...r.kernel.org>
Subject: [RFC PATCH 41/56] static_call: Add update_all_static_calls()

The update_all_static_calls() function re-scans all static call sites and
re-patches them.  This is used during re-patching.

Signed-off-by: David Kaplan <david.kaplan@....com>
---
 arch/x86/kernel/static_call.c |  3 ++-
 include/linux/static_call.h   |  2 ++
 kernel/static_call_inline.c   | 22 ++++++++++++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/static_call.c b/arch/x86/kernel/static_call.c
index 378c388d1b31..2d16d69b17d0 100644
--- a/arch/x86/kernel/static_call.c
+++ b/arch/x86/kernel/static_call.c
@@ -105,7 +105,8 @@ static void __ref __static_call_transform(void *insn, enum insn_type type,
 	if (memcmp(insn, code, size) == 0)
 		return;
 
-	if (system_state == SYSTEM_BOOTING || modinit)
+	/* alternatives_patched is false if we are doing dynamic re-patching. */
+	if (system_state == SYSTEM_BOOTING || modinit || !alternatives_patched)
 		return text_poke_early(insn, code, size);
 
 	smp_text_poke_single(insn, code, size, emulate);
diff --git a/include/linux/static_call.h b/include/linux/static_call.h
index 78a77a4ae0ea..cc5f28a04539 100644
--- a/include/linux/static_call.h
+++ b/include/linux/static_call.h
@@ -181,6 +181,8 @@ struct static_call_tramp_key {
 extern void __static_call_update(struct static_call_key *key, void *tramp, void *func);
 extern int static_call_mod_init(struct module *mod);
 extern int static_call_text_reserved(void *start, void *end);
+extern void update_all_static_calls(struct static_call_site *start,
+		struct static_call_site *stop, struct module *mod);
 
 extern long __static_call_return0(void);
 
diff --git a/kernel/static_call_inline.c b/kernel/static_call_inline.c
index 269683d41aa9..504b69496711 100644
--- a/kernel/static_call_inline.c
+++ b/kernel/static_call_inline.c
@@ -9,6 +9,7 @@
 #include <linux/cpu.h>
 #include <linux/processor.h>
 #include <asm/sections.h>
+#include <linux/kallsyms.h>
 
 extern struct static_call_site __start_static_call_sites[],
 			       __stop_static_call_sites[];
@@ -492,6 +493,27 @@ int static_call_text_reserved(void *start, void *end)
 	return __static_call_mod_text_reserved(start, end);
 }
 
+void update_all_static_calls(struct static_call_site *start,
+			     struct static_call_site *stop,
+			     struct module *mod)
+{
+	struct static_call_site *site;
+	struct static_call_key *key;
+
+	for (site = start; site < stop; site++) {
+		void *site_addr = static_call_addr(site);
+
+		/* All init code is gone when this function is called. */
+		if (is_kernel_text((u64) site_addr) ||
+		    (mod &&
+		     within_module_mem_type((u64) site_addr, mod, MOD_TEXT))) {
+			key = static_call_key(site);
+			arch_static_call_transform(site_addr, NULL, key->func,
+					static_call_is_tail(site));
+		}
+	}
+}
+
 int __init static_call_init(void)
 {
 	int ret;
-- 
2.34.1