| Message ID | 20181117185715.25198-3-ard.biesheuvel@linaro.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | bpf: permit JIT allocations to be served outside the module region | expand |
On Sat, Nov 17, 2018 at 6:58 PM Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > > All arch overrides of the __weak bpf_jit_free() amount to the same > thing: the allocated memory was never mapped read-only, and so > it does not have to be remapped to read-write before being freed. > > So in preparation of permitting arches to serve allocations for BPF > JIT programs from other regions than the module region, refactor > the existing bpf_jit_free() implementations to use the shared code > where possible, and only specialize the remap and free operations. > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > --- > arch/mips/net/bpf_jit.c | 7 ++----- > arch/powerpc/net/bpf_jit_comp.c | 7 ++----- > arch/powerpc/net/bpf_jit_comp64.c | 9 +++------ > arch/sparc/net/bpf_jit_comp_32.c | 7 ++----- > kernel/bpf/core.c | 15 +++++---------- > 5 files changed, 14 insertions(+), 31 deletions(-) > > diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c > index 1b69897274a1..5696bd7dccc7 100644 > --- a/arch/mips/net/bpf_jit.c > +++ b/arch/mips/net/bpf_jit.c > @@ -1261,10 +1261,7 @@ void bpf_jit_compile(struct bpf_prog *fp) > kfree(ctx.offsets); > } > > -void bpf_jit_free(struct bpf_prog *fp) > +void bpf_jit_binary_free(struct bpf_binary_header *hdr) > { > - if (fp->jited) > - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); > - > - bpf_prog_unlock_free(fp); > + module_memfree(hdr); > } > diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c > index a1ea1ea6b40d..5b5ce4a1b44b 100644 > --- a/arch/powerpc/net/bpf_jit_comp.c > +++ b/arch/powerpc/net/bpf_jit_comp.c > @@ -680,10 +680,7 @@ void bpf_jit_compile(struct bpf_prog *fp) > return; > } > > -void bpf_jit_free(struct bpf_prog *fp) > +void bpf_jit_binary_free(struct bpf_binary_header *hdr) > { > - if (fp->jited) > - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); > - > - bpf_prog_unlock_free(fp); > + module_memfree(hdr); > } > diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c > index 84c8f013a6c6..f64f1294bd62 100644 > --- a/arch/powerpc/net/bpf_jit_comp64.c > +++ b/arch/powerpc/net/bpf_jit_comp64.c > @@ -1021,11 +1021,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) > return fp; > } > > -/* Overriding bpf_jit_free() as we don't set images read-only. */ > -void bpf_jit_free(struct bpf_prog *fp) > +/* Overriding bpf_jit_binary_free() as we don't set images read-only. */ > +void bpf_jit_binary_free(struct bpf_binary_header *hdr) > { > - if (fp->jited) > - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); > - > - bpf_prog_unlock_free(fp); > + module_memfree(hdr); > } > diff --git a/arch/sparc/net/bpf_jit_comp_32.c b/arch/sparc/net/bpf_jit_comp_32.c > index 01bda6bc9e7f..589950d152cc 100644 > --- a/arch/sparc/net/bpf_jit_comp_32.c > +++ b/arch/sparc/net/bpf_jit_comp_32.c > @@ -756,10 +756,7 @@ cond_branch: f_offset = addrs[i + filter[i].jf]; > return; > } > > -void bpf_jit_free(struct bpf_prog *fp) > +void bpf_jit_binary_free(struct bpf_binary_header *hdr) > { > - if (fp->jited) > - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); > - > - bpf_prog_unlock_free(fp); > + module_memfree(hdr); > } > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > index 1a796e0799ec..29f766dac203 100644 > --- a/kernel/bpf/core.c > +++ b/kernel/bpf/core.c > @@ -646,25 +646,20 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, > return hdr; > } > > -void bpf_jit_binary_free(struct bpf_binary_header *hdr) > +void __weak bpf_jit_binary_free(struct bpf_binary_header *hdr) > { > - u32 pages = hdr->pages; > - > + bpf_jit_binary_unlock_ro(hdr); > module_memfree(hdr); > - bpf_jit_uncharge_modmem(pages); > } > > -/* This symbol is only overridden by archs that have different > - * requirements than the usual eBPF JITs, f.e. when they only > - * implement cBPF JIT, do not set images read-only, etc. > - */ Do you want to move the above comments to new weak function bpf_jit_binary_free? > -void __weak bpf_jit_free(struct bpf_prog *fp) > +void bpf_jit_free(struct bpf_prog *fp) > { > if (fp->jited) { > struct bpf_binary_header *hdr = bpf_jit_binary_hdr(fp); > + u32 pages = hdr->pages; > > - bpf_jit_binary_unlock_ro(hdr); > bpf_jit_binary_free(hdr); > + bpf_jit_uncharge_modmem(pages); > > WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(fp)); > } > -- > 2.17.1 >
On Sat, 17 Nov 2018 at 23:47, Y Song <ys114321@gmail.com> wrote: > > On Sat, Nov 17, 2018 at 6:58 PM Ard Biesheuvel > <ard.biesheuvel@linaro.org> wrote: > > > > All arch overrides of the __weak bpf_jit_free() amount to the same > > thing: the allocated memory was never mapped read-only, and so > > it does not have to be remapped to read-write before being freed. > > > > So in preparation of permitting arches to serve allocations for BPF > > JIT programs from other regions than the module region, refactor > > the existing bpf_jit_free() implementations to use the shared code > > where possible, and only specialize the remap and free operations. > > > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > > --- > > arch/mips/net/bpf_jit.c | 7 ++----- > > arch/powerpc/net/bpf_jit_comp.c | 7 ++----- > > arch/powerpc/net/bpf_jit_comp64.c | 9 +++------ > > arch/sparc/net/bpf_jit_comp_32.c | 7 ++----- > > kernel/bpf/core.c | 15 +++++---------- > > 5 files changed, 14 insertions(+), 31 deletions(-) > > > > diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c > > index 1b69897274a1..5696bd7dccc7 100644 > > --- a/arch/mips/net/bpf_jit.c > > +++ b/arch/mips/net/bpf_jit.c > > @@ -1261,10 +1261,7 @@ void bpf_jit_compile(struct bpf_prog *fp) > > kfree(ctx.offsets); > > } > > > > -void bpf_jit_free(struct bpf_prog *fp) > > +void bpf_jit_binary_free(struct bpf_binary_header *hdr) > > { > > - if (fp->jited) > > - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); > > - > > - bpf_prog_unlock_free(fp); > > + module_memfree(hdr); > > } > > diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c > > index a1ea1ea6b40d..5b5ce4a1b44b 100644 > > --- a/arch/powerpc/net/bpf_jit_comp.c > > +++ b/arch/powerpc/net/bpf_jit_comp.c > > @@ -680,10 +680,7 @@ void bpf_jit_compile(struct bpf_prog *fp) > > return; > > } > > > > -void bpf_jit_free(struct bpf_prog *fp) > > +void bpf_jit_binary_free(struct bpf_binary_header *hdr) > > { > > - if (fp->jited) > > - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); > > - > > - bpf_prog_unlock_free(fp); > > + module_memfree(hdr); > > } > > diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c > > index 84c8f013a6c6..f64f1294bd62 100644 > > --- a/arch/powerpc/net/bpf_jit_comp64.c > > +++ b/arch/powerpc/net/bpf_jit_comp64.c > > @@ -1021,11 +1021,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) > > return fp; > > } > > > > -/* Overriding bpf_jit_free() as we don't set images read-only. */ > > -void bpf_jit_free(struct bpf_prog *fp) > > +/* Overriding bpf_jit_binary_free() as we don't set images read-only. */ > > +void bpf_jit_binary_free(struct bpf_binary_header *hdr) > > { > > - if (fp->jited) > > - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); > > - > > - bpf_prog_unlock_free(fp); > > + module_memfree(hdr); > > } > > diff --git a/arch/sparc/net/bpf_jit_comp_32.c b/arch/sparc/net/bpf_jit_comp_32.c > > index 01bda6bc9e7f..589950d152cc 100644 > > --- a/arch/sparc/net/bpf_jit_comp_32.c > > +++ b/arch/sparc/net/bpf_jit_comp_32.c > > @@ -756,10 +756,7 @@ cond_branch: f_offset = addrs[i + filter[i].jf]; > > return; > > } > > > > -void bpf_jit_free(struct bpf_prog *fp) > > +void bpf_jit_binary_free(struct bpf_binary_header *hdr) > > { > > - if (fp->jited) > > - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); > > - > > - bpf_prog_unlock_free(fp); > > + module_memfree(hdr); > > } > > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > > index 1a796e0799ec..29f766dac203 100644 > > --- a/kernel/bpf/core.c > > +++ b/kernel/bpf/core.c > > @@ -646,25 +646,20 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, > > return hdr; > > } > > > > -void bpf_jit_binary_free(struct bpf_binary_header *hdr) > > +void __weak bpf_jit_binary_free(struct bpf_binary_header *hdr) > > { > > - u32 pages = hdr->pages; > > - > > + bpf_jit_binary_unlock_ro(hdr); > > module_memfree(hdr); > > - bpf_jit_uncharge_modmem(pages); > > } > > > > -/* This symbol is only overridden by archs that have different > > - * requirements than the usual eBPF JITs, f.e. when they only > > - * implement cBPF JIT, do not set images read-only, etc. > > - */ > > Do you want to move the above comments to > new weak function bpf_jit_binary_free? > Perhaps. But one thing I don't understand, looking at this again, is why we have these overrides in the first place. module_memfree() just calls vfree(), which takes down the mapping entirely (along with any updated permissions), and so remapping it back to r/w right before that seems rather pointless imo. Can we get rid of bpf_jit_binary_unlock_ro() entirely, and along with it, all these overrides for the free() path?
On Sun, Nov 18, 2018 at 3:55 PM Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > > On Sat, 17 Nov 2018 at 23:47, Y Song <ys114321@gmail.com> wrote: > > > > On Sat, Nov 17, 2018 at 6:58 PM Ard Biesheuvel > > <ard.biesheuvel@linaro.org> wrote: > > > > > > All arch overrides of the __weak bpf_jit_free() amount to the same > > > thing: the allocated memory was never mapped read-only, and so > > > it does not have to be remapped to read-write before being freed. > > > > > > So in preparation of permitting arches to serve allocations for BPF > > > JIT programs from other regions than the module region, refactor > > > the existing bpf_jit_free() implementations to use the shared code > > > where possible, and only specialize the remap and free operations. > > > > > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > > > --- > > > arch/mips/net/bpf_jit.c | 7 ++----- > > > arch/powerpc/net/bpf_jit_comp.c | 7 ++----- > > > arch/powerpc/net/bpf_jit_comp64.c | 9 +++------ > > > arch/sparc/net/bpf_jit_comp_32.c | 7 ++----- > > > kernel/bpf/core.c | 15 +++++---------- > > > 5 files changed, 14 insertions(+), 31 deletions(-) > > > > > > diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c > > > index 1b69897274a1..5696bd7dccc7 100644 > > > --- a/arch/mips/net/bpf_jit.c > > > +++ b/arch/mips/net/bpf_jit.c > > > @@ -1261,10 +1261,7 @@ void bpf_jit_compile(struct bpf_prog *fp) > > > kfree(ctx.offsets); > > > } > > > > > > -void bpf_jit_free(struct bpf_prog *fp) > > > +void bpf_jit_binary_free(struct bpf_binary_header *hdr) > > > { > > > - if (fp->jited) > > > - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); > > > - > > > - bpf_prog_unlock_free(fp); > > > + module_memfree(hdr); > > > } > > > diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c > > > index a1ea1ea6b40d..5b5ce4a1b44b 100644 > > > --- a/arch/powerpc/net/bpf_jit_comp.c > > > +++ b/arch/powerpc/net/bpf_jit_comp.c > > > @@ -680,10 +680,7 @@ void bpf_jit_compile(struct bpf_prog *fp) > > > return; > > > } > > > > > > -void bpf_jit_free(struct bpf_prog *fp) > > > +void bpf_jit_binary_free(struct bpf_binary_header *hdr) > > > { > > > - if (fp->jited) > > > - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); > > > - > > > - bpf_prog_unlock_free(fp); > > > + module_memfree(hdr); > > > } > > > diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c > > > index 84c8f013a6c6..f64f1294bd62 100644 > > > --- a/arch/powerpc/net/bpf_jit_comp64.c > > > +++ b/arch/powerpc/net/bpf_jit_comp64.c > > > @@ -1021,11 +1021,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) > > > return fp; > > > } > > > > > > -/* Overriding bpf_jit_free() as we don't set images read-only. */ > > > -void bpf_jit_free(struct bpf_prog *fp) > > > +/* Overriding bpf_jit_binary_free() as we don't set images read-only. */ > > > +void bpf_jit_binary_free(struct bpf_binary_header *hdr) > > > { > > > - if (fp->jited) > > > - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); > > > - > > > - bpf_prog_unlock_free(fp); > > > + module_memfree(hdr); > > > } > > > diff --git a/arch/sparc/net/bpf_jit_comp_32.c b/arch/sparc/net/bpf_jit_comp_32.c > > > index 01bda6bc9e7f..589950d152cc 100644 > > > --- a/arch/sparc/net/bpf_jit_comp_32.c > > > +++ b/arch/sparc/net/bpf_jit_comp_32.c > > > @@ -756,10 +756,7 @@ cond_branch: f_offset = addrs[i + filter[i].jf]; > > > return; > > > } > > > > > > -void bpf_jit_free(struct bpf_prog *fp) > > > +void bpf_jit_binary_free(struct bpf_binary_header *hdr) > > > { > > > - if (fp->jited) > > > - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); > > > - > > > - bpf_prog_unlock_free(fp); > > > + module_memfree(hdr); > > > } > > > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > > > index 1a796e0799ec..29f766dac203 100644 > > > --- a/kernel/bpf/core.c > > > +++ b/kernel/bpf/core.c > > > @@ -646,25 +646,20 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, > > > return hdr; > > > } > > > > > > -void bpf_jit_binary_free(struct bpf_binary_header *hdr) > > > +void __weak bpf_jit_binary_free(struct bpf_binary_header *hdr) > > > { > > > - u32 pages = hdr->pages; > > > - > > > + bpf_jit_binary_unlock_ro(hdr); > > > module_memfree(hdr); > > > - bpf_jit_uncharge_modmem(pages); > > > } > > > > > > -/* This symbol is only overridden by archs that have different > > > - * requirements than the usual eBPF JITs, f.e. when they only > > > - * implement cBPF JIT, do not set images read-only, etc. > > > - */ > > > > Do you want to move the above comments to > > new weak function bpf_jit_binary_free? > > > > Perhaps. But one thing I don't understand, looking at this again, is > why we have these overrides in the first place. module_memfree() just > calls vfree(), which takes down the mapping entirely (along with any > updated permissions), and so remapping it back to r/w right before > that seems rather pointless imo. > > Can we get rid of bpf_jit_binary_unlock_ro() entirely, and along with > it, all these overrides for the free() path? Maybe based on current implementation. Just a pure speculation. module_memfree() can be overwritten by arch specific implementation. The intention could be restoring the allocated page to its original permission just in case arch specific implementation of module_memfree() does different thing than default vfee().
diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c index 1b69897274a1..5696bd7dccc7 100644 --- a/arch/mips/net/bpf_jit.c +++ b/arch/mips/net/bpf_jit.c @@ -1261,10 +1261,7 @@ void bpf_jit_compile(struct bpf_prog *fp) kfree(ctx.offsets); } -void bpf_jit_free(struct bpf_prog *fp) +void bpf_jit_binary_free(struct bpf_binary_header *hdr) { - if (fp->jited) - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); - - bpf_prog_unlock_free(fp); + module_memfree(hdr); } diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index a1ea1ea6b40d..5b5ce4a1b44b 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -680,10 +680,7 @@ void bpf_jit_compile(struct bpf_prog *fp) return; } -void bpf_jit_free(struct bpf_prog *fp) +void bpf_jit_binary_free(struct bpf_binary_header *hdr) { - if (fp->jited) - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); - - bpf_prog_unlock_free(fp); + module_memfree(hdr); } diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 84c8f013a6c6..f64f1294bd62 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -1021,11 +1021,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) return fp; } -/* Overriding bpf_jit_free() as we don't set images read-only. */ -void bpf_jit_free(struct bpf_prog *fp) +/* Overriding bpf_jit_binary_free() as we don't set images read-only. */ +void bpf_jit_binary_free(struct bpf_binary_header *hdr) { - if (fp->jited) - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); - - bpf_prog_unlock_free(fp); + module_memfree(hdr); } diff --git a/arch/sparc/net/bpf_jit_comp_32.c b/arch/sparc/net/bpf_jit_comp_32.c index 01bda6bc9e7f..589950d152cc 100644 --- a/arch/sparc/net/bpf_jit_comp_32.c +++ b/arch/sparc/net/bpf_jit_comp_32.c @@ -756,10 +756,7 @@ cond_branch: f_offset = addrs[i + filter[i].jf]; return; } -void bpf_jit_free(struct bpf_prog *fp) +void bpf_jit_binary_free(struct bpf_binary_header *hdr) { - if (fp->jited) - bpf_jit_binary_free(bpf_jit_binary_hdr(fp)); - - bpf_prog_unlock_free(fp); + module_memfree(hdr); } diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 1a796e0799ec..29f766dac203 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -646,25 +646,20 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, return hdr; } -void bpf_jit_binary_free(struct bpf_binary_header *hdr) +void __weak bpf_jit_binary_free(struct bpf_binary_header *hdr) { - u32 pages = hdr->pages; - + bpf_jit_binary_unlock_ro(hdr); module_memfree(hdr); - bpf_jit_uncharge_modmem(pages); } -/* This symbol is only overridden by archs that have different - * requirements than the usual eBPF JITs, f.e. when they only - * implement cBPF JIT, do not set images read-only, etc. - */ -void __weak bpf_jit_free(struct bpf_prog *fp) +void bpf_jit_free(struct bpf_prog *fp) { if (fp->jited) { struct bpf_binary_header *hdr = bpf_jit_binary_hdr(fp); + u32 pages = hdr->pages; - bpf_jit_binary_unlock_ro(hdr); bpf_jit_binary_free(hdr); + bpf_jit_uncharge_modmem(pages); WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(fp)); }
All arch overrides of the __weak bpf_jit_free() amount to the same thing: the allocated memory was never mapped read-only, and so it does not have to be remapped to read-write before being freed. So in preparation of permitting arches to serve allocations for BPF JIT programs from other regions than the module region, refactor the existing bpf_jit_free() implementations to use the shared code where possible, and only specialize the remap and free operations. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- arch/mips/net/bpf_jit.c | 7 ++----- arch/powerpc/net/bpf_jit_comp.c | 7 ++----- arch/powerpc/net/bpf_jit_comp64.c | 9 +++------ arch/sparc/net/bpf_jit_comp_32.c | 7 ++----- kernel/bpf/core.c | 15 +++++---------- 5 files changed, 14 insertions(+), 31 deletions(-)