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Message-ID: <20250603111446.2609381-6-rppt@kernel.org>
Date: Tue, 3 Jun 2025 14:14:45 +0300
From: Mike Rapoport <rppt@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Ingo Molnar <mingo@...hat.com>,
Jürgen Groß <jgross@...e.com>,
Mike Rapoport <rppt@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Xin Li <xin@...or.com>,
linux-kernel@...r.kernel.org,
stable@...r.kernel.org,
x86@...nel.org
Subject: [PATCH 5/5] Revert "mm/execmem: Unify early execmem_cache behaviour"
From: "Mike Rapoport (Microsoft)" <rppt@...nel.org>
The commit d6d1e3e6580c ("mm/execmem: Unify early execmem_cache
behaviour") changed early behaviour of execemem ROX cache to allow its
usage in early x86 code that allocates text pages when
CONFIG_MITGATION_ITS is enabled.
The permission management of the pages allocated from execmem for ITS
mitigation is now completely contained in arch/x86/kernel/alternatives.c
and therefore there is no need to special case early allocations in
execmem.
This reverts commit d6d1e3e6580ca35071ad474381f053cbf1fb6414.
Signed-off-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
---
arch/x86/mm/init_32.c | 3 ---
arch/x86/mm/init_64.c | 3 ---
include/linux/execmem.h | 8 +-------
mm/execmem.c | 40 +++-------------------------------------
4 files changed, 4 insertions(+), 50 deletions(-)
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index bb8d99e717b9..148eba50265a 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -30,7 +30,6 @@
#include <linux/initrd.h>
#include <linux/cpumask.h>
#include <linux/gfp.h>
-#include <linux/execmem.h>
#include <asm/asm.h>
#include <asm/bios_ebda.h>
@@ -756,8 +755,6 @@ void mark_rodata_ro(void)
pr_info("Write protecting kernel text and read-only data: %luk\n",
size >> 10);
- execmem_cache_make_ro();
-
kernel_set_to_readonly = 1;
#ifdef CONFIG_CPA_DEBUG
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 949a447f75ec..7c4f6f591f2b 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -34,7 +34,6 @@
#include <linux/gfp.h>
#include <linux/kcore.h>
#include <linux/bootmem_info.h>
-#include <linux/execmem.h>
#include <asm/processor.h>
#include <asm/bios_ebda.h>
@@ -1392,8 +1391,6 @@ void mark_rodata_ro(void)
(end - start) >> 10);
set_memory_ro(start, (end - start) >> PAGE_SHIFT);
- execmem_cache_make_ro();
-
kernel_set_to_readonly = 1;
/*
diff --git a/include/linux/execmem.h b/include/linux/execmem.h
index ca42d5e46ccc..3be35680a54f 100644
--- a/include/linux/execmem.h
+++ b/include/linux/execmem.h
@@ -54,7 +54,7 @@ enum execmem_range_flags {
EXECMEM_ROX_CACHE = (1 << 1),
};
-#if defined(CONFIG_ARCH_HAS_EXECMEM_ROX) && defined(CONFIG_EXECMEM)
+#ifdef CONFIG_ARCH_HAS_EXECMEM_ROX
/**
* execmem_fill_trapping_insns - set memory to contain instructions that
* will trap
@@ -94,15 +94,9 @@ int execmem_make_temp_rw(void *ptr, size_t size);
* Return: 0 on success or negative error code on failure.
*/
int execmem_restore_rox(void *ptr, size_t size);
-
-/*
- * Called from mark_readonly(), where the system transitions to ROX.
- */
-void execmem_cache_make_ro(void);
#else
static inline int execmem_make_temp_rw(void *ptr, size_t size) { return 0; }
static inline int execmem_restore_rox(void *ptr, size_t size) { return 0; }
-static inline void execmem_cache_make_ro(void) { }
#endif
/**
diff --git a/mm/execmem.c b/mm/execmem.c
index 6f7a2653b280..e6c4f5076ca8 100644
--- a/mm/execmem.c
+++ b/mm/execmem.c
@@ -254,34 +254,6 @@ static void *__execmem_cache_alloc(struct execmem_range *range, size_t size)
return ptr;
}
-static bool execmem_cache_rox = false;
-
-void execmem_cache_make_ro(void)
-{
- struct maple_tree *free_areas = &execmem_cache.free_areas;
- struct maple_tree *busy_areas = &execmem_cache.busy_areas;
- MA_STATE(mas_free, free_areas, 0, ULONG_MAX);
- MA_STATE(mas_busy, busy_areas, 0, ULONG_MAX);
- struct mutex *mutex = &execmem_cache.mutex;
- void *area;
-
- execmem_cache_rox = true;
-
- mutex_lock(mutex);
-
- mas_for_each(&mas_free, area, ULONG_MAX) {
- unsigned long pages = mas_range_len(&mas_free) >> PAGE_SHIFT;
- set_memory_ro(mas_free.index, pages);
- }
-
- mas_for_each(&mas_busy, area, ULONG_MAX) {
- unsigned long pages = mas_range_len(&mas_busy) >> PAGE_SHIFT;
- set_memory_ro(mas_busy.index, pages);
- }
-
- mutex_unlock(mutex);
-}
-
static int execmem_cache_populate(struct execmem_range *range, size_t size)
{
unsigned long vm_flags = VM_ALLOW_HUGE_VMAP;
@@ -302,15 +274,9 @@ static int execmem_cache_populate(struct execmem_range *range, size_t size)
/* fill memory with instructions that will trap */
execmem_fill_trapping_insns(p, alloc_size, /* writable = */ true);
- if (execmem_cache_rox) {
- err = set_memory_rox((unsigned long)p, vm->nr_pages);
- if (err)
- goto err_free_mem;
- } else {
- err = set_memory_x((unsigned long)p, vm->nr_pages);
- if (err)
- goto err_free_mem;
- }
+ err = set_memory_rox((unsigned long)p, vm->nr_pages);
+ if (err)
+ goto err_free_mem;
err = execmem_cache_add(p, alloc_size);
if (err)
--
2.47.2
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