| Message ID | 20230918072955.2507221-10-rppt@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | mm: jit/text allocator | expand |
On Mon, Sep 18, 2023 at 12:31 AM Mike Rapoport <rppt@kernel.org> wrote: > [...] > @@ -135,5 +138,13 @@ struct execmem_params __init *execmem_arch_params(void) > > range->pgprot = prot; > > + execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_START; > + execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_END; .end = VMALLOC_END. Thanks, Song > + > + if (strict_module_rwx_enabled()) > + execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_ROX; > + else > + execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_EXEC; > + > return &execmem_params; > } > -- > 2.39.2 > >
Hi Mike, Le 18/09/2023 à 09:29, Mike Rapoport a écrit : > From: "Mike Rapoport (IBM)" <rppt@kernel.org> > > powerpc overrides kprobes::alloc_insn_page() to remove writable > permissions when STRICT_MODULE_RWX is on. > > Add definition of EXECMEM_KRPOBES to execmem_params to allow using the > generic kprobes::alloc_insn_page() with the desired permissions. > > As powerpc uses breakpoint instructions to inject kprobes, it does not > need to constrain kprobe allocations to the modules area and can use the > entire vmalloc address space. I don't understand what you mean here. Does it mean kprobe allocation doesn't need to be executable ? I don't think so based on the pgprot you set. On powerpc book3s/32, vmalloc space is not executable. Only modules space is executable. X/NX cannot be set on a per page basis, it can only be set on a 256 Mbytes segment basis. See commit c49643319715 ("powerpc/32s: Only leave NX unset on segments used for modules") and 6ca055322da8 ("powerpc/32s: Use dedicated segment for modules with STRICT_KERNEL_RWX") and 7bee31ad8e2f ("powerpc/32s: Fix is_module_segment() when MODULES_VADDR is defined"). So if your intention is still to have an executable kprobes, then you can't use vmalloc address space. Christophe > > Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org> > --- > arch/powerpc/kernel/kprobes.c | 14 -------------- > arch/powerpc/kernel/module.c | 11 +++++++++++ > 2 files changed, 11 insertions(+), 14 deletions(-) > > diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c > index 62228c7072a2..14c5ddec3056 100644 > --- a/arch/powerpc/kernel/kprobes.c > +++ b/arch/powerpc/kernel/kprobes.c > @@ -126,20 +126,6 @@ kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offse > return (kprobe_opcode_t *)(addr + offset); > } > > -void *alloc_insn_page(void) > -{ > - void *page; > - > - page = execmem_text_alloc(EXECMEM_KPROBES, PAGE_SIZE); > - if (!page) > - return NULL; > - > - if (strict_module_rwx_enabled()) > - set_memory_rox((unsigned long)page, 1); > - > - return page; > -} > - > int arch_prepare_kprobe(struct kprobe *p) > { > int ret = 0; > diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c > index 824d9541a310..bf2c62aef628 100644 > --- a/arch/powerpc/kernel/module.c > +++ b/arch/powerpc/kernel/module.c > @@ -95,6 +95,9 @@ static struct execmem_params execmem_params __ro_after_init = { > [EXECMEM_DEFAULT] = { > .alignment = 1, > }, > + [EXECMEM_KPROBES] = { > + .alignment = 1, > + }, > [EXECMEM_MODULE_DATA] = { > .alignment = 1, > }, > @@ -135,5 +138,13 @@ struct execmem_params __init *execmem_arch_params(void) > > range->pgprot = prot; > > + execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_START; > + execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_END; > + > + if (strict_module_rwx_enabled()) > + execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_ROX; > + else > + execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_EXEC; > + > return &execmem_params; > }
On Thu, Sep 21, 2023 at 03:30:46PM -0700, Song Liu wrote: > On Mon, Sep 18, 2023 at 12:31 AM Mike Rapoport <rppt@kernel.org> wrote: > > > [...] > > @@ -135,5 +138,13 @@ struct execmem_params __init *execmem_arch_params(void) > > > > range->pgprot = prot; > > > > + execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_START; > > + execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_END; > > .end = VMALLOC_END. Thanks, this should have been execmem_params.ranges[EXECMEM_KPROBES].start = range->start; execmem_params.ranges[EXECMEM_KPROBES].end = range->end; where range points to the same range as EXECMEM_MODULE_TEXT. > Thanks, > Song > > > + > > + if (strict_module_rwx_enabled()) > > + execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_ROX; > > + else > > + execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_EXEC; > > + > > return &execmem_params; > > } > > -- > > 2.39.2 > > > >
Hi Christophe, On Fri, Sep 22, 2023 at 10:32:46AM +0000, Christophe Leroy wrote: > Hi Mike, > > Le 18/09/2023 à 09:29, Mike Rapoport a écrit : > > From: "Mike Rapoport (IBM)" <rppt@kernel.org> > > > > powerpc overrides kprobes::alloc_insn_page() to remove writable > > permissions when STRICT_MODULE_RWX is on. > > > > Add definition of EXECMEM_KRPOBES to execmem_params to allow using the > > generic kprobes::alloc_insn_page() with the desired permissions. > > > > As powerpc uses breakpoint instructions to inject kprobes, it does not > > need to constrain kprobe allocations to the modules area and can use the > > entire vmalloc address space. > > I don't understand what you mean here. Does it mean kprobe allocation > doesn't need to be executable ? I don't think so based on the pgprot you > set. > > On powerpc book3s/32, vmalloc space is not executable. Only modules > space is executable. X/NX cannot be set on a per page basis, it can only > be set on a 256 Mbytes segment basis. > > See commit c49643319715 ("powerpc/32s: Only leave NX unset on segments > used for modules") and 6ca055322da8 ("powerpc/32s: Use dedicated segment > for modules with STRICT_KERNEL_RWX") and 7bee31ad8e2f ("powerpc/32s: Fix > is_module_segment() when MODULES_VADDR is defined"). > > So if your intention is still to have an executable kprobes, then you > can't use vmalloc address space. Right, and I've fixed the KPROBES range to uses the same range as MODULES. The commit message is stale and I need to update it. > Christophe > > > > > Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org> > > --- > > arch/powerpc/kernel/kprobes.c | 14 -------------- > > arch/powerpc/kernel/module.c | 11 +++++++++++ > > 2 files changed, 11 insertions(+), 14 deletions(-) > > > > diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c > > index 62228c7072a2..14c5ddec3056 100644 > > --- a/arch/powerpc/kernel/kprobes.c > > +++ b/arch/powerpc/kernel/kprobes.c > > @@ -126,20 +126,6 @@ kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offse > > return (kprobe_opcode_t *)(addr + offset); > > } > > > > -void *alloc_insn_page(void) > > -{ > > - void *page; > > - > > - page = execmem_text_alloc(EXECMEM_KPROBES, PAGE_SIZE); > > - if (!page) > > - return NULL; > > - > > - if (strict_module_rwx_enabled()) > > - set_memory_rox((unsigned long)page, 1); > > - > > - return page; > > -} > > - > > int arch_prepare_kprobe(struct kprobe *p) > > { > > int ret = 0; > > diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c > > index 824d9541a310..bf2c62aef628 100644 > > --- a/arch/powerpc/kernel/module.c > > +++ b/arch/powerpc/kernel/module.c > > @@ -95,6 +95,9 @@ static struct execmem_params execmem_params __ro_after_init = { > > [EXECMEM_DEFAULT] = { > > .alignment = 1, > > }, > > + [EXECMEM_KPROBES] = { > > + .alignment = 1, > > + }, > > [EXECMEM_MODULE_DATA] = { > > .alignment = 1, > > }, > > @@ -135,5 +138,13 @@ struct execmem_params __init *execmem_arch_params(void) > > > > range->pgprot = prot; > > > > + execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_START; > > + execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_END; > > + > > + if (strict_module_rwx_enabled()) > > + execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_ROX; > > + else > > + execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_EXEC; > > + > > return &execmem_params; > > }
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index 62228c7072a2..14c5ddec3056 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -126,20 +126,6 @@ kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offse return (kprobe_opcode_t *)(addr + offset); } -void *alloc_insn_page(void) -{ - void *page; - - page = execmem_text_alloc(EXECMEM_KPROBES, PAGE_SIZE); - if (!page) - return NULL; - - if (strict_module_rwx_enabled()) - set_memory_rox((unsigned long)page, 1); - - return page; -} - int arch_prepare_kprobe(struct kprobe *p) { int ret = 0; diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c index 824d9541a310..bf2c62aef628 100644 --- a/arch/powerpc/kernel/module.c +++ b/arch/powerpc/kernel/module.c @@ -95,6 +95,9 @@ static struct execmem_params execmem_params __ro_after_init = { [EXECMEM_DEFAULT] = { .alignment = 1, }, + [EXECMEM_KPROBES] = { + .alignment = 1, + }, [EXECMEM_MODULE_DATA] = { .alignment = 1, }, @@ -135,5 +138,13 @@ struct execmem_params __init *execmem_arch_params(void) range->pgprot = prot; + execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_START; + execmem_params.ranges[EXECMEM_KPROBES].start = VMALLOC_END; + + if (strict_module_rwx_enabled()) + execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_ROX; + else + execmem_params.ranges[EXECMEM_KPROBES].pgprot = PAGE_KERNEL_EXEC; + return &execmem_params; }