[PATCH 2/6] arm64: compat: Allow 32-bit vdso and sigpage to co-exist
Mark Rutland
mark.rutland at arm.com
Tue Jun 23 06:19:20 EDT 2020
On Tue, Jun 23, 2020 at 09:54:32AM +0100, Will Deacon wrote:
> In preparation for removing the signal trampoline from the compat vDSO,
> allow the sigpage and the compat vDSO to co-exist.
>
> Signed-off-by: Will Deacon <will at kernel.org>
Can we please add something like:
| For the moment the vDSO signal trampoline will still be used when
| built. Subsequent patches will move to the sigpage consistently.
... since that explains the code left in signal32.c as of this patch.
Otherwise this looks good to me, so with something to that effect:
Reviewed-by: Mark Rutland <mark.rutland at arm.com>
Mark.
> ---
> arch/arm64/include/asm/mmu.h | 3 ++
> arch/arm64/kernel/Makefile | 2 --
> arch/arm64/kernel/signal32.c | 2 +-
> arch/arm64/kernel/vdso.c | 61 +++++++++++++++++-------------------
> 4 files changed, 32 insertions(+), 36 deletions(-)
>
> diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
> index 68140fdd89d6..8444df000181 100644
> --- a/arch/arm64/include/asm/mmu.h
> +++ b/arch/arm64/include/asm/mmu.h
> @@ -19,6 +19,9 @@
>
> typedef struct {
> atomic64_t id;
> +#ifdef CONFIG_COMPAT
> + void *sigpage;
> +#endif
> void *vdso;
> unsigned long flags;
> } mm_context_t;
> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
> index 151f28521f1e..a561cbb91d4d 100644
> --- a/arch/arm64/kernel/Makefile
> +++ b/arch/arm64/kernel/Makefile
> @@ -29,9 +29,7 @@ $(obj)/%.stub.o: $(obj)/%.o FORCE
>
> obj-$(CONFIG_COMPAT) += sys32.o signal32.o \
> sys_compat.o
> -ifneq ($(CONFIG_COMPAT_VDSO), y)
> obj-$(CONFIG_COMPAT) += sigreturn32.o
> -endif
> obj-$(CONFIG_KUSER_HELPERS) += kuser32.o
> obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o entry-ftrace.o
> obj-$(CONFIG_MODULES) += module.o
> diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
> index 82feca6f7052..0aa0b33744de 100644
> --- a/arch/arm64/kernel/signal32.c
> +++ b/arch/arm64/kernel/signal32.c
> @@ -371,7 +371,7 @@ static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka,
> if (ka->sa.sa_flags & SA_SIGINFO)
> idx += 3;
>
> - retcode = (unsigned long)current->mm->context.vdso +
> + retcode = (unsigned long)current->mm->context.sigpage +
> (idx << 2) + thumb;
> #endif
> }
> diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
> index 4e016574bd91..e546df0efefb 100644
> --- a/arch/arm64/kernel/vdso.c
> +++ b/arch/arm64/kernel/vdso.c
> @@ -191,15 +191,12 @@ enum aarch32_map {
> #ifdef CONFIG_COMPAT_VDSO
> AA32_MAP_VVAR,
> AA32_MAP_VDSO,
> -#else
> - AA32_MAP_SIGPAGE
> #endif
> + AA32_MAP_SIGPAGE
> };
>
> static struct page *aarch32_vectors_page __ro_after_init;
> -#ifndef CONFIG_COMPAT_VDSO
> static struct page *aarch32_sig_page __ro_after_init;
> -#endif
>
> static struct vm_special_mapping aarch32_vdso_maps[] = {
> [AA32_MAP_VECTORS] = {
> @@ -214,12 +211,11 @@ static struct vm_special_mapping aarch32_vdso_maps[] = {
> .name = "[vdso]",
> .mremap = aarch32_vdso_mremap,
> },
> -#else
> +#endif /* CONFIG_COMPAT_VDSO */
> [AA32_MAP_SIGPAGE] = {
> .name = "[sigpage]", /* ABI */
> .pages = &aarch32_sig_page,
> },
> -#endif /* CONFIG_COMPAT_VDSO */
> };
>
> static int aarch32_alloc_kuser_vdso_page(void)
> @@ -242,27 +238,11 @@ static int aarch32_alloc_kuser_vdso_page(void)
> return 0;
> }
>
> -#ifdef CONFIG_COMPAT_VDSO
> -static int __aarch32_alloc_vdso_pages(void)
> -{
> - int ret;
> -
> - vdso_info[VDSO_ABI_AA32].dm = &aarch32_vdso_maps[AA32_MAP_VVAR];
> - vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_maps[AA32_MAP_VDSO];
> -
> - ret = __vdso_init(VDSO_ABI_AA32);
> - if (ret)
> - return ret;
> -
> - return aarch32_alloc_kuser_vdso_page();
> -}
> -#else
> -static int __aarch32_alloc_vdso_pages(void)
> +static int aarch32_alloc_sigpage(void)
> {
> extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
> int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start;
> unsigned long sigpage;
> - int ret;
>
> sigpage = get_zeroed_page(GFP_ATOMIC);
> if (!sigpage)
> @@ -271,18 +251,34 @@ static int __aarch32_alloc_vdso_pages(void)
> memcpy((void *)sigpage, __aarch32_sigret_code_start, sigret_sz);
> aarch32_sig_page = virt_to_page(sigpage);
> flush_dcache_page(aarch32_sig_page);
> + return 0;
> +}
>
> - ret = aarch32_alloc_kuser_vdso_page();
> - if (ret)
> - free_page(sigpage);
> +#ifdef CONFIG_COMPAT_VDSO
> +static int __aarch32_alloc_vdso_pages(void)
> +{
> + vdso_info[VDSO_ABI_AA32].dm = &aarch32_vdso_maps[AA32_MAP_VVAR];
> + vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_maps[AA32_MAP_VDSO];
>
> - return ret;
> + return __vdso_init(VDSO_ABI_AA32);
> }
> #endif /* CONFIG_COMPAT_VDSO */
>
> static int __init aarch32_alloc_vdso_pages(void)
> {
> - return __aarch32_alloc_vdso_pages();
> + int ret;
> +
> +#ifdef CONFIG_COMPAT_VDSO
> + ret = __aarch32_alloc_vdso_pages();
> + if (ret)
> + return ret;
> +#endif
> +
> + ret = aarch32_alloc_sigpage();
> + if (ret)
> + return ret;
> +
> + return aarch32_alloc_kuser_vdso_page();
> }
> arch_initcall(aarch32_alloc_vdso_pages);
>
> @@ -305,7 +301,6 @@ static int aarch32_kuser_helpers_setup(struct mm_struct *mm)
> return PTR_ERR_OR_ZERO(ret);
> }
>
> -#ifndef CONFIG_COMPAT_VDSO
> static int aarch32_sigreturn_setup(struct mm_struct *mm)
> {
> unsigned long addr;
> @@ -328,12 +323,11 @@ static int aarch32_sigreturn_setup(struct mm_struct *mm)
> if (IS_ERR(ret))
> goto out;
>
> - mm->context.vdso = (void *)addr;
> + mm->context.sigpage = (void *)addr;
>
> out:
> return PTR_ERR_OR_ZERO(ret);
> }
> -#endif /* !CONFIG_COMPAT_VDSO */
>
> int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
> {
> @@ -352,10 +346,11 @@ int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
> mm,
> bprm,
> uses_interp);
> -#else
> - ret = aarch32_sigreturn_setup(mm);
> + if (ret)
> + goto out;
> #endif /* CONFIG_COMPAT_VDSO */
>
> + ret = aarch32_sigreturn_setup(mm);
> out:
> mmap_write_unlock(mm);
> return ret;
> --
> 2.27.0.111.gc72c7da667-goog
>
>
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