On Fri, Feb 25, 2022 at 1:57 AM Palmer Dabbelt [off-list ref] wrote:

On Thu, 24 Feb 2022 00:54:07 PST (-0800), guoren@kernel.org wrote:

quoted

From: Guo Ren <redacted>

Reconstruct __setup_additional_pages() by appending vdso info
pointer argument to meet compat_vdso_info requirement. And change
vm_special_mapping *dm, *cm initialization into static.

Signed-off-by: Guo Ren <redacted>
Signed-off-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Palmer Dabbelt <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
---
 arch/riscv/include/asm/elf.h |   5 ++
 arch/riscv/include/asm/mmu.h |   1 +
 arch/riscv/kernel/vdso.c     | 103 +++++++++++++++++++++++------------
 3 files changed, 74 insertions(+), 35 deletions(-)

diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h
index 3a4293dc7229..d87d3bcc758d 100644
--- a/arch/riscv/include/asm/elf.h
+++ b/arch/riscv/include/asm/elf.h

@@ -134,5 +134,10 @@ do {    if ((ex).e_ident[EI_CLASS] == ELFCLASS32)                \
 typedef compat_ulong_t                       compat_elf_greg_t;
 typedef compat_elf_greg_t            compat_elf_gregset_t[ELF_NGREG];

+extern int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
+                                           int uses_interp);
+#define compat_arch_setup_additional_pages \
+                             compat_arch_setup_additional_pages
+
 #endif /* CONFIG_COMPAT */
 #endif /* _ASM_RISCV_ELF_H */

diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
index 0099dc116168..cedcf8ea3c76 100644
--- a/arch/riscv/include/asm/mmu.h
+++ b/arch/riscv/include/asm/mmu.h

@@ -16,6 +16,7 @@ typedef struct {
      atomic_long_t id;
 #endif
      void *vdso;
+     void *vdso_info;
 #ifdef CONFIG_SMP
      /* A local icache flush is needed before user execution can resume. */
      cpumask_t icache_stale_mask;

diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
index a9436a65161a..f864811aa011 100644
--- a/arch/riscv/kernel/vdso.c
+++ b/arch/riscv/kernel/vdso.c

@@ -23,6 +23,9 @@ struct vdso_data {
 #endif

 extern char vdso_start[], vdso_end[];
+#ifdef CONFIG_COMPAT
+extern char compat_vdso_start[], compat_vdso_end[];
+#endif

 enum vvar_pages {
      VVAR_DATA_PAGE_OFFSET,

@@ -30,6 +33,11 @@ enum vvar_pages {
      VVAR_NR_PAGES,
 };

+enum rv_vdso_map {
+     RV_VDSO_MAP_VVAR,
+     RV_VDSO_MAP_VDSO,
+};
+
 #define VVAR_SIZE  (VVAR_NR_PAGES << PAGE_SHIFT)

 /*

@@ -52,12 +60,6 @@ struct __vdso_info {
      struct vm_special_mapping *cm;
 };

-static struct __vdso_info vdso_info __ro_after_init = {
-     .name = "vdso",
-     .vdso_code_start = vdso_start,
-     .vdso_code_end = vdso_end,
-};
-
 static int vdso_mremap(const struct vm_special_mapping *sm,
                     struct vm_area_struct *new_vma)
 {

@@ -66,37 +68,33 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
      return 0;
 }

-static int __init __vdso_init(void)
+static void __init __vdso_init(struct __vdso_info *vdso_info)
 {
      unsigned int i;
      struct page **vdso_pagelist;
      unsigned long pfn;

-     if (memcmp(vdso_info.vdso_code_start, "\177ELF", 4)) {
-             pr_err("vDSO is not a valid ELF object!\n");
-             return -EINVAL;
-     }
+     if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4))
+             panic("vDSO is not a valid ELF object!\n");

-     vdso_info.vdso_pages = (
-             vdso_info.vdso_code_end -
-             vdso_info.vdso_code_start) >>
+     vdso_info->vdso_pages = (
+             vdso_info->vdso_code_end -
+             vdso_info->vdso_code_start) >>
              PAGE_SHIFT;

-     vdso_pagelist = kcalloc(vdso_info.vdso_pages,
+     vdso_pagelist = kcalloc(vdso_info->vdso_pages,
                              sizeof(struct page *),
                              GFP_KERNEL);
      if (vdso_pagelist == NULL)
-             return -ENOMEM;
+             panic("vDSO kcalloc failed!\n");

      /* Grab the vDSO code pages. */
-     pfn = sym_to_pfn(vdso_info.vdso_code_start);
+     pfn = sym_to_pfn(vdso_info->vdso_code_start);

-     for (i = 0; i < vdso_info.vdso_pages; i++)
+     for (i = 0; i < vdso_info->vdso_pages; i++)
              vdso_pagelist[i] = pfn_to_page(pfn + i);

-     vdso_info.cm->pages = vdso_pagelist;
-
-     return 0;
+     vdso_info->cm->pages = vdso_pagelist;
 }

 #ifdef CONFIG_TIME_NS

@@ -116,13 +114,14 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
 {
      struct mm_struct *mm = task->mm;
      struct vm_area_struct *vma;
+     struct __vdso_info *vdso_info = mm->context.vdso_info;

      mmap_read_lock(mm);

      for (vma = mm->mmap; vma; vma = vma->vm_next) {
              unsigned long size = vma->vm_end - vma->vm_start;

-             if (vma_is_special_mapping(vma, vdso_info.dm))
+             if (vma_is_special_mapping(vma, vdso_info->dm))
                      zap_page_range(vma, vma->vm_start, size);
      }

@@ -187,11 +186,6 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
      return vmf_insert_pfn(vma, vmf->address, pfn);
 }

-enum rv_vdso_map {
-     RV_VDSO_MAP_VVAR,
-     RV_VDSO_MAP_VDSO,
-};
-
 static struct vm_special_mapping rv_vdso_maps[] __ro_after_init = {
      [RV_VDSO_MAP_VVAR] = {
              .name   = "[vvar]",

@@ -203,25 +197,44 @@ static struct vm_special_mapping rv_vdso_maps[] __ro_after_init = {
      },
 };

+static struct __vdso_info vdso_info __ro_after_init = {
+     .name = "vdso",
+     .vdso_code_start = vdso_start,
+     .vdso_code_end = vdso_end,
+     .dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
+     .cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
+};
+
+#ifdef CONFIG_COMPAT
+static struct __vdso_info compat_vdso_info __ro_after_init = {
+     .name = "compat_vdso",
+     .vdso_code_start = compat_vdso_start,
+     .vdso_code_end = compat_vdso_end,
+     .dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR],
+     .cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO],
+};
+#endif
+
 static int __init vdso_init(void)
 {
-     vdso_info.dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR];
-     vdso_info.cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO];
+     __vdso_init(&vdso_info);
+     __vdso_init(&compat_vdso_info);

An autobuilder is pointing out an issue here.  I'm assuming just an `#if
defined(CONFIG_COMPAT)` will fix it, I'm OK squashing that in if it's
the only issue -- a fixed one never hurts, though ;)

Thx for pointing out, my fault, it should be:
 static int __init vdso_init(void)
 {
        __vdso_init(&vdso_info);
+#ifdef CONFIG_COMPAT
        __vdso_init(&compat_vdso_info);
+#endif

I'll try to take another look soon.

Okay.

quoted

-     return __vdso_init();
+     return 0;
 }
 arch_initcall(vdso_init);

 static int __setup_additional_pages(struct mm_struct *mm,
                                  struct linux_binprm *bprm,
-                                 int uses_interp)
+                                 int uses_interp,
+                                 struct __vdso_info *vdso_info)
 {
      unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
      void *ret;

      BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES);

-     vdso_text_len = vdso_info.vdso_pages << PAGE_SHIFT;
+     vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT;
      /* Be sure to map the data page */
      vdso_mapping_len = vdso_text_len + VVAR_SIZE;

@@ -232,16 +245,18 @@ static int __setup_additional_pages(struct mm_struct *mm,
      }

      ret = _install_special_mapping(mm, vdso_base, VVAR_SIZE,
-             (VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info.dm);
+             (VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info->dm);
      if (IS_ERR(ret))
              goto up_fail;

      vdso_base += VVAR_SIZE;
      mm->context.vdso = (void *)vdso_base;
+     mm->context.vdso_info = (void *)vdso_info;
+
      ret =
         _install_special_mapping(mm, vdso_base, vdso_text_len,
              (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
-             vdso_info.cm);
+             vdso_info->cm);

      if (IS_ERR(ret))
              goto up_fail;

@@ -253,6 +268,24 @@ static int __setup_additional_pages(struct mm_struct *mm,
      return PTR_ERR(ret);
 }

+#ifdef CONFIG_COMPAT
+int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
+                                    int uses_interp)
+{
+     struct mm_struct *mm = current->mm;
+     int ret;
+
+     if (mmap_write_lock_killable(mm))
+             return -EINTR;
+
+     ret = __setup_additional_pages(mm, bprm, uses_interp,
+                                                     &compat_vdso_info);
+     mmap_write_unlock(mm);
+
+     return ret;
+}
+#endif
+
 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 {
      struct mm_struct *mm = current->mm;

@@ -261,7 +294,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
      if (mmap_write_lock_killable(mm))
              return -EINTR;

-     ret = __setup_additional_pages(mm, bprm, uses_interp);
+     ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info);
      mmap_write_unlock(mm);

      return ret;

-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/