| Message ID | 20200724050553.1724168-4-jarkko.sakkinen@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arch/x86: kprobes: Remove MODULES dependency | expand |
* Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote: > +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); Had to dig around a bit to find the source of this restriction. Might make sense to clarify this comment to: /* * This memory may be read-only, and freeing VM_FLUSH_RESET_PERMS memory * in an interrupt is not supported by vmalloc. */ Thanks, Ingo
On Fri, Jul 24, 2020 at 11:22:58AM +0200, Ingo Molnar wrote: > > * Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote: > > > +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); > > Had to dig around a bit to find the source of this restriction. Might > make sense to clarify this comment to: > > /* > * This memory may be read-only, and freeing VM_FLUSH_RESET_PERMS memory > * in an interrupt is not supported by vmalloc. > */ This definitely clarifies and is a better explanation. I updated the commit accordingly. Thank you. > > Thanks, > > Ingo /Jarkko
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); +}
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@kvack.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> --- 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