Commit 3e39ce26 authored by Vasily Gorbik's avatar Vasily Gorbik
Browse files

s390/kasan: add KASAN_VMALLOC support 



Add KASAN_VMALLOC support which now enables vmalloc memory area access
checks as well as enables usage of VMAP_STACK under kasan.

KASAN_VMALLOC changes the way vmalloc and modules areas shadow memory
is handled. With this new approach only top level page tables are
pre-populated and lower levels are filled dynamically upon memory
allocation.

Acked-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 1b68ac86

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -124,6 +124,7 @@ config S390 
	select HAVE_ARCH_JUMP_LABEL

	select HAVE_ARCH_JUMP_LABEL_RELATIVE

	select HAVE_ARCH_KASAN

	select HAVE_ARCH_KASAN_VMALLOC

	select CPU_NO_EFFICIENT_FFS if !HAVE_MARCH_Z9_109_FEATURES

	select HAVE_ARCH_SECCOMP_FILTER

	select HAVE_ARCH_SOFT_DIRTY

arch/s390/mm/kasan_init.c

+56 −12
Original line number Diff line number Diff line
@@ -82,7 +82,8 @@ static pte_t * __init kasan_early_pte_alloc(void) 
enum populate_mode {

	POPULATE_ONE2ONE,

	POPULATE_MAP,

	POPULATE_ZERO_SHADOW

	POPULATE_ZERO_SHADOW,

	POPULATE_SHALLOW

};

static void __init kasan_early_vmemmap_populate(unsigned long address,

						unsigned long end,
@@ -116,6 +117,12 @@ static void __init kasan_early_vmemmap_populate(unsigned long address, 
			pgd_populate(&init_mm, pg_dir, p4_dir);

		}



		if (IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING) &&

		    mode == POPULATE_SHALLOW) {

			address = (address + P4D_SIZE) & P4D_MASK;

			continue;

		}



		p4_dir = p4d_offset(pg_dir, address);

		if (p4d_none(*p4_dir)) {

			if (mode == POPULATE_ZERO_SHADOW &&
@@ -130,6 +137,12 @@ static void __init kasan_early_vmemmap_populate(unsigned long address, 
			p4d_populate(&init_mm, p4_dir, pu_dir);

		}



		if (!IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING) &&

		    mode == POPULATE_SHALLOW) {

			address = (address + PUD_SIZE) & PUD_MASK;

			continue;

		}



		pu_dir = pud_offset(p4_dir, address);

		if (pud_none(*pu_dir)) {

			if (mode == POPULATE_ZERO_SHADOW &&
@@ -195,6 +208,9 @@ static void __init kasan_early_vmemmap_populate(unsigned long address, 
				page = kasan_early_shadow_page;

				pte_val(*pt_dir) = __pa(page) | pgt_prot_zero;

				break;

			case POPULATE_SHALLOW:

				/* should never happen */

				break;

			}

		}

		address += PAGE_SIZE;
@@ -315,20 +331,48 @@ void __init kasan_early_init(void) 
	 * Current memory layout:

	 * +- 0 -------------+	   +- shadow start -+

	 * | 1:1 ram mapping |	  /| 1/8 ram	    |

	 * |		     |	 / |		    |

	 * +- end of ram ----+	/  +----------------+

	 * | ... gap ...     |/  |	kasan	  |

	 * | ... gap ...     | /   |		    |

	 * |		     |/    |	kasan	    |

	 * +- shadow start --+	   |	zero	    |

	 * | 1/8 addr space  |	   |	page	    |

	 * +- shadow end    -+	   |	mapping	    |

	 * | ... gap ...     |\    |  (untracked)   |

	 * +- vmalloc area  -+ \   |		    |

	 * | vmalloc_size    |	\  |		    |

	 * +- modules vaddr -+	 \ +----------------+

	 * | 2Gb	     |	  \|	  unmapped  | allocated per module

	 * +-----------------+	   +- shadow end ---+

	 *

	 * Current memory layout (KASAN_VMALLOC):

	 * +- 0 -------------+	   +- shadow start -+

	 * | 1:1 ram mapping |	  /| 1/8 ram	    |

	 * |		     |	 / |		    |

	 * +- end of ram ----+	/  +----------------+

	 * | ... gap ...     | /   |	kasan	    |

	 * |		     |/    |	zero	    |

	 * +- shadow start --+	   |	page	    |

	 * | 1/8 addr space  |	   |	mapping     |

	 * +- shadow end    -+	   |  (untracked)   |

	 * | ... gap ...     |\    |		    |

	 * +- vmalloc area  -+ \   +- vmalloc area -+

	 * | vmalloc_size    |	\  |shallow populate|

	 * +- modules vaddr -+	 \ +- modules area -+

	 * | 2Gb	     |	  \|shallow populate|

	 * +-----------------+	   +- shadow end ---+

	 */

	/* populate kasan shadow (for identity mapping and zero page mapping) */

	kasan_early_vmemmap_populate(__sha(0), __sha(memsize), POPULATE_MAP);

	if (IS_ENABLED(CONFIG_MODULES))

		untracked_mem_end = vmax - MODULES_LEN;

	if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {

		untracked_mem_end = vmax - vmalloc_size - MODULES_LEN;

		/* shallowly populate kasan shadow for vmalloc and modules */

		kasan_early_vmemmap_populate(__sha(untracked_mem_end),

					     __sha(vmax), POPULATE_SHALLOW);

	}

	/* populate kasan shadow for untracked memory */

	kasan_early_vmemmap_populate(__sha(max_physmem_end),

				     __sha(untracked_mem_end),

				     POPULATE_ZERO_SHADOW);

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