On Sat, 18 Jul 2020 19:23:59 +0300 Mike Rapoport <rppt@xxxxxxxxxx> wrote: > On Fri, Jul 17, 2020 at 06:04:17AM +0300, Jarkko Sakkinen wrote: > > Introduce functions for allocating memory for dynamic trampolines, such > > as kprobes. An arch can promote the availability of these functions with > > CONFIG_ARCH_HAS_TEXT_ALLOC. Provide default/fallback implementation > > wrapping module_alloc() and module_memfree(). > > > > Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx> > > Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> > > Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> > > --- > > include/linux/vmalloc.h | 23 +++++++++++++++++++++++ > > 1 file changed, 23 insertions(+) > > > > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h > > index 0221f852a7e1..e981436e30b6 100644 > > --- a/include/linux/vmalloc.h > > +++ b/include/linux/vmalloc.h > > @@ -9,6 +9,7 @@ > > #include <asm/page.h> /* pgprot_t */ > > #include <linux/rbtree.h> > > #include <linux/overflow.h> > > +#include <linux/moduleloader.h> > > > > #include <asm/vmalloc.h> > > > > @@ -249,4 +250,26 @@ pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms) > > int register_vmap_purge_notifier(struct notifier_block *nb); > > int unregister_vmap_purge_notifier(struct notifier_block *nb); > > > > +#ifdef CONFIG_ARCH_HAS_TEXT_ALLOC > > +/* > > + * Allocate memory to be used for dynamic trampoline code. > > + */ > > +void *text_alloc(unsigned long size); > > + > > +/* > > + * Free memory returned from text_alloc(). > > + */ > > +void text_free(void *region); > > +#else > > +static inline void *text_alloc(unsigned long size) > > +{ > > + return module_alloc(size); > > +} > > + > > +static inline void text_free(void *region) > > +{ > > + module_memfree(region); > > +} > > Using module_alloc() as the default implementation of generic > text_alloc() does not sound right to me. > > I would suggest rename module_alloc() to text_alloc() on x86, as Peter > proposed and then add text_alloc_kprobes() that can be overridden by the > architectures. x86 could use text_alloc(), arm64 vmalloc() with options > of their choice and the fallback would remain module_alloc(). Something > like (untested) patch below: Hmm, of course we need some more work on this patch (e.g. MODULE_STATE_* for callbacks), but basically, this direction seems good to me for the first step. If other dynamic trampoline code (ftrace and bpf) are interested in replacing the module_alloc() with text_alloc_*(), we should revisit how we can unify it (or at least share the common parts.) BTW, this changes CONFIG_MODULES dependency according to the architecture implementation. It also should be noted somewhere. Thank you, > From 928b6903e76ebf5790fc415f9eed390e400e5bc3 Mon Sep 17 00:00:00 2001 > From: Mike Rapoport <rppt@xxxxxxxxxxxxx> > Date: Sat, 18 Jul 2020 19:13:02 +0300 > Subject: [PATCH] kprobes: introduce text_alloc_kprobes() and > text_free_kprobes() > > Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> > --- > arch/Kconfig | 5 ++++- > arch/arm64/Kconfig | 1 + > arch/arm64/kernel/probes/kprobes.c | 10 ++++++++-- > arch/x86/Kconfig | 3 ++- > arch/x86/kernel/kprobes/core.c | 9 ++++----- > include/linux/kprobes.h | 17 +++++++++++++++-- > kernel/kprobes.c | 8 ++++---- > 7 files changed, 38 insertions(+), 15 deletions(-) > > diff --git a/arch/Kconfig b/arch/Kconfig > index 8cc35dc556c7..c0589b3b3225 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -61,7 +61,7 @@ config OPROFILE_NMI_TIMER > > config KPROBES > bool "Kprobes" > - depends on MODULES > + depends on MODULES || HAVE_KPROBES_TEXT_ALLOC > depends on HAVE_KPROBES > select KALLSYMS > help > @@ -186,6 +186,9 @@ config HAVE_IOREMAP_PROT > config HAVE_KPROBES > bool > > +config HAVE_KPROBES_TEXT_ALLOC > + bool > + > config HAVE_KRETPROBES > bool > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 66dc41fd49f2..abc0538b13ef 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -177,6 +177,7 @@ config ARM64 > select HAVE_STACKPROTECTOR > select HAVE_SYSCALL_TRACEPOINTS > select HAVE_KPROBES > + select HAVE_KPROBES_TEXT_ALLOC > select HAVE_KRETPROBES > select HAVE_GENERIC_VDSO > select IOMMU_DMA if IOMMU_SUPPORT > diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c > index 5290f17a4d80..fac8c6020040 100644 > --- a/arch/arm64/kernel/probes/kprobes.c > +++ b/arch/arm64/kernel/probes/kprobes.c > @@ -118,13 +118,19 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) > return 0; > } > > -void *alloc_insn_page(void) > +void *text_alloc_kprobes(unsigned long size) > { > - return __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, VMALLOC_END, > + return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END, > GFP_KERNEL, PAGE_KERNEL_ROX, VM_FLUSH_RESET_PERMS, > NUMA_NO_NODE, __builtin_return_address(0)); > } > > +void text_free_kprobes(void *mem) > +{ > + lockdep_assert_irqs_enabled(); > + vfree(mem); > +} > + > /* arm kprobe: install breakpoint in text */ > void __kprobes arch_arm_kprobe(struct kprobe *p) > { > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 883da0abf779..d08b92f91531 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -190,6 +190,7 @@ config X86 > select HAVE_KERNEL_XZ > select HAVE_KPROBES > select HAVE_KPROBES_ON_FTRACE > + select HAVE_KPROBES_TEXT_ALLOC > select HAVE_FUNCTION_ERROR_INJECTION > select HAVE_KRETPROBES > select HAVE_KVM > diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c > index ada39ddbc922..a3e8f01c62d4 100644 > --- a/arch/x86/kernel/kprobes/core.c > +++ b/arch/x86/kernel/kprobes/core.c > @@ -418,12 +418,11 @@ static int prepare_boost(kprobe_opcode_t *buf, struct kprobe *p, > return len; > } > > -/* Make page to RO mode when allocate it */ > -void *alloc_insn_page(void) > +void *text_alloc_kprobes(unsigned long size) > { > void *page; > > - page = module_alloc(PAGE_SIZE); > + page = text_alloc(size); > if (!page) > return NULL; > > @@ -444,9 +443,9 @@ void *alloc_insn_page(void) > } > > /* Recover page to RW mode before releasing it */ > -void free_insn_page(void *page) > +void text_free_kprobes(void *page) > { > - module_memfree(page); > + text_free(page); > } > > static int arch_copy_kprobe(struct kprobe *p) > diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h > index 6adf90f248d7..dbc9c71d4ec4 100644 > --- a/include/linux/kprobes.h > +++ b/include/linux/kprobes.h > @@ -27,6 +27,7 @@ > #include <linux/rcupdate.h> > #include <linux/mutex.h> > #include <linux/ftrace.h> > +#include <linux/moduleloader.h> > #include <asm/kprobes.h> > > #ifdef CONFIG_KPROBES > @@ -374,8 +375,20 @@ int enable_kprobe(struct kprobe *kp); > > void dump_kprobe(struct kprobe *kp); > > -void *alloc_insn_page(void); > -void free_insn_page(void *page); > +#ifdef CONFIG_HAVE_KPROBES_TEXT_ALLOC > +void *text_alloc_kprobes(unsigned long size); > +void text_free_kprobes(void *page); > +#else > +static inline void *text_alloc_kprobes(unsigned long size) > +{ > + return module_alloc(size); > +} > + > +static inline void text_free_kprobes(void *page) > +{ > + module_memfree(page); > +} > +#endif > > #else /* !CONFIG_KPROBES: */ > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 2e97febeef77..c4f107682250 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -109,14 +109,14 @@ enum kprobe_slot_state { > SLOT_USED = 2, > }; > > -void __weak *alloc_insn_page(void) > +static void *alloc_insn_page(void) > { > - return module_alloc(PAGE_SIZE); > + return text_alloc_kprobes(PAGE_SIZE); > } > > -void __weak free_insn_page(void *page) > +static void free_insn_page(void *page) > { > - module_memfree(page); > + text_free_kprobes(page); > } > > struct kprobe_insn_cache kprobe_insn_slots = { > -- > 2.26.2 > > > > +#endif > > + > > #endif /* _LINUX_VMALLOC_H */ > > -- > > 2.25.1 > > > > -- > Sincerely yours, > Mike. -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>