Implement text_alloc() and text_free() with with the vmalloc API. These can
be used to allocate pages for trampoline code without relying on the module
loader code.
Cc: linux-mm@xxxxxxxxx
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
arch/x86/Kconfig | 3 +++
arch/x86/kernel/Makefile | 1 +
arch/x86/kernel/text_alloc.c | 41 ++++++++++++++++++++++++++++++++++++
3 files changed, 45 insertions(+)
create mode 100644 arch/x86/kernel/text_alloc.c
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0dea7fdd7a00..a4ee5d1300f6 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2035,6 +2035,9 @@ config KEXEC_FILE
config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE
+config ARCH_HAS_TEXT_ALLOC
+ def_bool y
+
config KEXEC_SIG
bool "Verify kernel signature during kexec_file_load() syscall"
depends on KEXEC_FILE
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index e77261db2391..fa1415424ae3 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -68,6 +68,7 @@ obj-y += tsc.o tsc_msr.o io_delay.o rtc.o
obj-y += pci-iommu_table.o
obj-y += resource.o
obj-y += irqflags.o
+obj-y += text_alloc.o
obj-y += process.o
obj-y += fpu/
diff --git a/arch/x86/kernel/text_alloc.c b/arch/x86/kernel/text_alloc.c
new file mode 100644
index 000000000000..f31c2d82c258
--- /dev/null
+++ b/arch/x86/kernel/text_alloc.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Kernel module help for x86.
+ * Copyright (C) 2001 Rusty Russell.
+ */
+
+#include <linux/kasan.h>
+#include <linux/mm.h>
+#include <linux/moduleloader.h>
+#include <linux/vmalloc.h>
+#include <asm/setup.h>
+
+void *text_alloc(unsigned long size)
+{
+ void *p;
+
+ if (PAGE_ALIGN(size) > MODULES_LEN)
+ return NULL;
+
+ p = __vmalloc_node_range(size, MODULE_ALIGN, MODULES_VADDR, MODULES_END,
+ GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE,
+ __builtin_return_address(0));
+
+ if (p && (kasan_module_alloc(p, size) < 0)) {
+ vfree(p);
+ return NULL;
+ }
+
+ return p;
+}
+
+void text_free(void *region)
+{
+ /*
+ * This memory may be RO, and freeing RO memory in an interrupt is not
+ * supported by vmalloc.
+ */
+ lockdep_assert_irqs_enabled();
+
+ vfree(region);
+}
--
2.25.1
