| Message ID | 20201026160342.3705327-2-arnd@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/4] arm64: cpu_errata: fix override-init warnings | expand |
On Mon, Oct 26, 2020 at 05:03:29PM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > When CONFIG_COMPAT_VDSO is disabled, we get a warning > about a potential out-of-bounds access: > > arch/arm64/kernel/vdso.c: In function 'aarch32_vdso_mremap': > arch/arm64/kernel/vdso.c:86:37: warning: array subscript 1 is above array bounds of 'struct vdso_abi_info[1]' [-Warray-bounds] > 86 | unsigned long vdso_size = vdso_info[abi].vdso_code_end - > | ~~~~~~~~~^~~~~ > > This is all in dead code however that the compiler is unable to > eliminate by itself. > > Change the array to individual local variables that can be > dropped in dead code elimination to let the compiler understand > this better. > > Fixes: 0cbc2659123e ("arm64: vdso32: Remove a bunch of #ifdef CONFIG_COMPAT_VDSO guards") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> This looks like a nice cleanup to me! I agree we don't need the array here. Reviewed-by: Mark Rutland <mark.rutland@arm.com> Thanks, Mark. > --- > arch/arm64/kernel/vdso.c | 56 ++++++++++++++++++---------------------- > 1 file changed, 25 insertions(+), 31 deletions(-) > > diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c > index debb8995d57f..0b69d2894742 100644 > --- a/arch/arm64/kernel/vdso.c > +++ b/arch/arm64/kernel/vdso.c > @@ -286,36 +286,9 @@ static int aarch32_vdso_mremap(const struct vm_special_mapping *sm, > return __vdso_remap(VDSO_ABI_AA32, sm, new_vma); > } > > -enum aarch32_map { > - AA32_MAP_VECTORS, /* kuser helpers */ > - AA32_MAP_SIGPAGE, > - AA32_MAP_VVAR, > - AA32_MAP_VDSO, > -}; > - > static struct page *aarch32_vectors_page __ro_after_init; > static struct page *aarch32_sig_page __ro_after_init; > > -static struct vm_special_mapping aarch32_vdso_maps[] = { > - [AA32_MAP_VECTORS] = { > - .name = "[vectors]", /* ABI */ > - .pages = &aarch32_vectors_page, > - }, > - [AA32_MAP_SIGPAGE] = { > - .name = "[sigpage]", /* ABI */ > - .pages = &aarch32_sig_page, > - }, > - [AA32_MAP_VVAR] = { > - .name = "[vvar]", > - .fault = vvar_fault, > - .mremap = vvar_mremap, > - }, > - [AA32_MAP_VDSO] = { > - .name = "[vdso]", > - .mremap = aarch32_vdso_mremap, > - }, > -}; > - > static int aarch32_alloc_kuser_vdso_page(void) > { > extern char __kuser_helper_start[], __kuser_helper_end[]; > @@ -352,14 +325,25 @@ static int aarch32_alloc_sigpage(void) > return 0; > } > > +static struct vm_special_mapping aarch32_vdso_map_vvar = { > + .name = "[vvar]", > + .fault = vvar_fault, > + .mremap = vvar_mremap, > +}; > + > +static struct vm_special_mapping aarch32_vdso_map_vdso = { > + .name = "[vdso]", > + .mremap = aarch32_vdso_mremap, > +}; > + > static int __aarch32_alloc_vdso_pages(void) > { > > if (!IS_ENABLED(CONFIG_COMPAT_VDSO)) > return 0; > > - vdso_info[VDSO_ABI_AA32].dm = &aarch32_vdso_maps[AA32_MAP_VVAR]; > - vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_maps[AA32_MAP_VDSO]; > + vdso_info[VDSO_ABI_AA32].dm = &aarch32_vdso_map_vvar; > + vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_map_vdso; > > return __vdso_init(VDSO_ABI_AA32); > } > @@ -380,6 +364,11 @@ static int __init aarch32_alloc_vdso_pages(void) > } > arch_initcall(aarch32_alloc_vdso_pages); > > +static struct vm_special_mapping aarch32_vdso_map_vectors = { > + .name = "[vectors]", /* ABI */ > + .pages = &aarch32_vectors_page, > +}; > + > static int aarch32_kuser_helpers_setup(struct mm_struct *mm) > { > void *ret; > @@ -394,11 +383,16 @@ static int aarch32_kuser_helpers_setup(struct mm_struct *mm) > ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE, > VM_READ | VM_EXEC | > VM_MAYREAD | VM_MAYEXEC, > - &aarch32_vdso_maps[AA32_MAP_VECTORS]); > + &aarch32_vdso_map_vectors); > > return PTR_ERR_OR_ZERO(ret); > } > > +static struct vm_special_mapping aarch32_vdso_map_sigpage = { > + .name = "[sigpage]", /* ABI */ > + .pages = &aarch32_sig_page, > +}; > + > static int aarch32_sigreturn_setup(struct mm_struct *mm) > { > unsigned long addr; > @@ -417,7 +411,7 @@ static int aarch32_sigreturn_setup(struct mm_struct *mm) > ret = _install_special_mapping(mm, addr, PAGE_SIZE, > VM_READ | VM_EXEC | VM_MAYREAD | > VM_MAYWRITE | VM_MAYEXEC, > - &aarch32_vdso_maps[AA32_MAP_SIGPAGE]); > + &aarch32_vdso_map_sigpage); > if (IS_ERR(ret)) > goto out; > > -- > 2.27.0 >
On Mon, Oct 26, 2020 at 5:55 PM Mark Rutland <mark.rutland@arm.com> wrote: > On Mon, Oct 26, 2020 at 05:03:29PM +0100, Arnd Bergmann wrote: > > From: Arnd Bergmann <arnd@arndb.de> > > > > When CONFIG_COMPAT_VDSO is disabled, we get a warning > > about a potential out-of-bounds access: > > > > arch/arm64/kernel/vdso.c: In function 'aarch32_vdso_mremap': > > arch/arm64/kernel/vdso.c:86:37: warning: array subscript 1 is above array bounds of 'struct vdso_abi_info[1]' [-Warray-bounds] > > 86 | unsigned long vdso_size = vdso_info[abi].vdso_code_end - > > | ~~~~~~~~~^~~~~ > > > > This is all in dead code however that the compiler is unable to > > eliminate by itself. > > > > Change the array to individual local variables that can be > > dropped in dead code elimination to let the compiler understand > > this better. > > > > Fixes: 0cbc2659123e ("arm64: vdso32: Remove a bunch of #ifdef CONFIG_COMPAT_VDSO guards") > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > This looks like a nice cleanup to me! I agree we don't need the array > here. > > Reviewed-by: Mark Rutland <mark.rutland@arm.com> Thanks! I see the patch now conflicts with "mm: forbid splitting special mappings" in -mm, by Dmitry Safonov. I have rebased my patch on top, should I send it to Andrew for inclusion in -mm then? Arnd
On 10/29/20 1:35 PM, Arnd Bergmann wrote: > On Mon, Oct 26, 2020 at 5:55 PM Mark Rutland <mark.rutland@arm.com> wrote: >> On Mon, Oct 26, 2020 at 05:03:29PM +0100, Arnd Bergmann wrote: >>> From: Arnd Bergmann <arnd@arndb.de> >>> >>> When CONFIG_COMPAT_VDSO is disabled, we get a warning >>> about a potential out-of-bounds access: >>> >>> arch/arm64/kernel/vdso.c: In function 'aarch32_vdso_mremap': >>> arch/arm64/kernel/vdso.c:86:37: warning: array subscript 1 is above array bounds of 'struct vdso_abi_info[1]' [-Warray-bounds] >>> 86 | unsigned long vdso_size = vdso_info[abi].vdso_code_end - >>> | ~~~~~~~~~^~~~~ >>> >>> This is all in dead code however that the compiler is unable to >>> eliminate by itself. >>> >>> Change the array to individual local variables that can be >>> dropped in dead code elimination to let the compiler understand >>> this better. >>> >>> Fixes: 0cbc2659123e ("arm64: vdso32: Remove a bunch of #ifdef CONFIG_COMPAT_VDSO guards") >>> Signed-off-by: Arnd Bergmann <arnd@arndb.de> >> >> This looks like a nice cleanup to me! I agree we don't need the array >> here. >> >> Reviewed-by: Mark Rutland <mark.rutland@arm.com> > > Thanks! > > I see the patch now conflicts with "mm: forbid splitting special mappings" > in -mm, by Dmitry Safonov. I have rebased my patch on top, should > I send it to Andrew for inclusion in -mm then? Makes sense to me. I plan to add some more patches on top that will make tracking of user landing (on vdso/sigpage/etc) common between architectures in generic code. So, I think it's probably good idea to keep it in one place, -mm tree seems like a proper place for it. Thanks, Dmitry
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index debb8995d57f..0b69d2894742 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -286,36 +286,9 @@ static int aarch32_vdso_mremap(const struct vm_special_mapping *sm, return __vdso_remap(VDSO_ABI_AA32, sm, new_vma); } -enum aarch32_map { - AA32_MAP_VECTORS, /* kuser helpers */ - AA32_MAP_SIGPAGE, - AA32_MAP_VVAR, - AA32_MAP_VDSO, -}; - static struct page *aarch32_vectors_page __ro_after_init; static struct page *aarch32_sig_page __ro_after_init; -static struct vm_special_mapping aarch32_vdso_maps[] = { - [AA32_MAP_VECTORS] = { - .name = "[vectors]", /* ABI */ - .pages = &aarch32_vectors_page, - }, - [AA32_MAP_SIGPAGE] = { - .name = "[sigpage]", /* ABI */ - .pages = &aarch32_sig_page, - }, - [AA32_MAP_VVAR] = { - .name = "[vvar]", - .fault = vvar_fault, - .mremap = vvar_mremap, - }, - [AA32_MAP_VDSO] = { - .name = "[vdso]", - .mremap = aarch32_vdso_mremap, - }, -}; - static int aarch32_alloc_kuser_vdso_page(void) { extern char __kuser_helper_start[], __kuser_helper_end[]; @@ -352,14 +325,25 @@ static int aarch32_alloc_sigpage(void) return 0; } +static struct vm_special_mapping aarch32_vdso_map_vvar = { + .name = "[vvar]", + .fault = vvar_fault, + .mremap = vvar_mremap, +}; + +static struct vm_special_mapping aarch32_vdso_map_vdso = { + .name = "[vdso]", + .mremap = aarch32_vdso_mremap, +}; + static int __aarch32_alloc_vdso_pages(void) { if (!IS_ENABLED(CONFIG_COMPAT_VDSO)) return 0; - vdso_info[VDSO_ABI_AA32].dm = &aarch32_vdso_maps[AA32_MAP_VVAR]; - vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_maps[AA32_MAP_VDSO]; + vdso_info[VDSO_ABI_AA32].dm = &aarch32_vdso_map_vvar; + vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_map_vdso; return __vdso_init(VDSO_ABI_AA32); } @@ -380,6 +364,11 @@ static int __init aarch32_alloc_vdso_pages(void) } arch_initcall(aarch32_alloc_vdso_pages); +static struct vm_special_mapping aarch32_vdso_map_vectors = { + .name = "[vectors]", /* ABI */ + .pages = &aarch32_vectors_page, +}; + static int aarch32_kuser_helpers_setup(struct mm_struct *mm) { void *ret; @@ -394,11 +383,16 @@ static int aarch32_kuser_helpers_setup(struct mm_struct *mm) ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE, VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYEXEC, - &aarch32_vdso_maps[AA32_MAP_VECTORS]); + &aarch32_vdso_map_vectors); return PTR_ERR_OR_ZERO(ret); } +static struct vm_special_mapping aarch32_vdso_map_sigpage = { + .name = "[sigpage]", /* ABI */ + .pages = &aarch32_sig_page, +}; + static int aarch32_sigreturn_setup(struct mm_struct *mm) { unsigned long addr; @@ -417,7 +411,7 @@ static int aarch32_sigreturn_setup(struct mm_struct *mm) ret = _install_special_mapping(mm, addr, PAGE_SIZE, VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, - &aarch32_vdso_maps[AA32_MAP_SIGPAGE]); + &aarch32_vdso_map_sigpage); if (IS_ERR(ret)) goto out;