152 lines
5.3 KiB
Diff
152 lines
5.3 KiB
Diff
From edb2bd52885ccc2fbe3e0825efe0ac55951a7710 Mon Sep 17 00:00:00 2001
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From: "qiwu.chen@transsion.com" <qiwu.chen@transsion.com>
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Date: Fri, 22 Dec 2023 03:30:33 +0000
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Subject: [PATCH 1/6] arm64: support HW Tag-Based KASAN (MTE) mode
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Kernel commit 2e903b914797 ("kasan, arm64: implement HW_TAGS runtime")
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introduced Hardware Tag-Based KASAN (MTE) mode for ARMv8.5 and later
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CPUs, which uses the Top Byte Ignore (TBI) feature of arm64 CPUs to
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store a pointer tag in the top byte of kernel pointers.
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Currently, crash utility cannot load MTE ramdump due to access invalid
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HW Tag-Based kernel virtual addresses. Here's the example error message:
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please wait... (gathering kmem slab cache data)
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crash: invalid kernel virtual address: f1ffff80c000201c type: "kmem_cache objsize/object_size"
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please wait... (gathering task table data)
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crash: invalid kernel virtual address: f9ffff8239c2cde0 type: "xa_node shift"
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This patch replaces the orignal generic_is_kvaddr() with arm64_is_kvaddr(),
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which checks the validity for a HW Tag-Based kvaddr. mte_tag_reset() is
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used to convert a Tag-Based kvaddr to untaggged kvaddr in arm64_VTOP()
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and arm64_IS_VMALLOC_ADDR().
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Signed-off-by: chenqiwu <qiwu.chen@transsion.com>
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Signed-off-by: Kazuhito Hagio <k-hagio-ab@nec.com>
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Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
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---
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arm64.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
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defs.h | 1 +
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2 files changed, 50 insertions(+), 3 deletions(-)
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diff --git a/arm64.c b/arm64.c
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index 57965c6cb3c8..6ab10ca9b5be 100644
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--- a/arm64.c
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+++ b/arm64.c
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@@ -102,6 +102,41 @@ struct kernel_range {
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static struct kernel_range *arm64_get_va_range(struct machine_specific *ms);
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static void arm64_get_struct_page_size(struct machine_specific *ms);
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+/* mte tag shift bit */
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+#define MTE_TAG_SHIFT 56
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+/* native kernel pointers tag */
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+#define KASAN_TAG_KERNEL 0xFF
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+/* minimum value for random tags */
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+#define KASAN_TAG_MIN 0xF0
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+/* right shift the tag to MTE_TAG_SHIFT bit */
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+#define mte_tag_shifted(tag) ((ulong)(tag) << MTE_TAG_SHIFT)
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+/* get the top byte value of the original kvaddr */
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+#define mte_tag_get(addr) (unsigned char)((ulong)(addr) >> MTE_TAG_SHIFT)
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+/* reset the top byte to get an untaggged kvaddr */
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+#define mte_tag_reset(addr) (((ulong)addr & ~mte_tag_shifted(KASAN_TAG_KERNEL)) | \
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+ mte_tag_shifted(KASAN_TAG_KERNEL))
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+
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+static inline bool is_mte_kvaddr(ulong addr)
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+{
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+ /* check for ARM64_MTE enabled */
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+ if (!(machdep->flags & ARM64_MTE))
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+ return false;
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+
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+ /* check the validity of HW Tag-Based kvaddr */
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+ if (mte_tag_get(addr) >= KASAN_TAG_MIN && mte_tag_get(addr) < KASAN_TAG_KERNEL)
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+ return true;
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+
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+ return false;
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+}
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+
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+static int arm64_is_kvaddr(ulong addr)
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+{
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+ if (is_mte_kvaddr(addr))
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+ return (mte_tag_reset(addr) >= (ulong)(machdep->kvbase));
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+
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+ return (addr >= (ulong)(machdep->kvbase));
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+}
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+
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static void arm64_calc_kernel_start(void)
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{
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struct machine_specific *ms = machdep->machspec;
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@@ -182,6 +217,9 @@ arm64_init(int when)
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if (kernel_symbol_exists("kimage_voffset"))
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machdep->flags |= NEW_VMEMMAP;
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+ if (kernel_symbol_exists("cpu_enable_mte"))
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+ machdep->flags |= ARM64_MTE;
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+
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if (!machdep->pagesize && arm64_get_vmcoreinfo(&value, "PAGESIZE", NUM_DEC))
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machdep->pagesize = (unsigned int)value;
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@@ -262,7 +300,7 @@ arm64_init(int when)
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machdep->kvbase = ARM64_VA_START;
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ms->userspace_top = ARM64_USERSPACE_TOP;
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}
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- machdep->is_kvaddr = generic_is_kvaddr;
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+ machdep->is_kvaddr = arm64_is_kvaddr;
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machdep->kvtop = arm64_kvtop;
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/* The defaults */
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@@ -975,6 +1013,8 @@ arm64_dump_machdep_table(ulong arg)
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fprintf(fp, "%sFLIPPED_VM", others++ ? "|" : "");
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if (machdep->flags & HAS_PHYSVIRT_OFFSET)
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fprintf(fp, "%sHAS_PHYSVIRT_OFFSET", others++ ? "|" : "");
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+ if (machdep->flags & ARM64_MTE)
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+ fprintf(fp, "%sARM64_MTE", others++ ? "|" : "");
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fprintf(fp, ")\n");
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fprintf(fp, " kvbase: %lx\n", machdep->kvbase);
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@@ -1023,7 +1063,7 @@ arm64_dump_machdep_table(ulong arg)
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fprintf(fp, " dis_filter: arm64_dis_filter()\n");
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fprintf(fp, " cmd_mach: arm64_cmd_mach()\n");
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fprintf(fp, " get_smp_cpus: arm64_get_smp_cpus()\n");
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- fprintf(fp, " is_kvaddr: generic_is_kvaddr()\n");
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+ fprintf(fp, " is_kvaddr: arm64_is_kvaddr()\n");
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fprintf(fp, " is_uvaddr: arm64_is_uvaddr()\n");
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fprintf(fp, " value_to_symbol: generic_machdep_value_to_symbol()\n");
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fprintf(fp, " init_kernel_pgd: arm64_init_kernel_pgd\n");
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@@ -1633,6 +1673,9 @@ ulong arm64_PTOV(ulong paddr)
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ulong
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arm64_VTOP(ulong addr)
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{
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+ if (is_mte_kvaddr(addr))
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+ addr = mte_tag_reset(addr);
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+
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if (machdep->flags & NEW_VMEMMAP) {
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if (machdep->machspec->VA_START &&
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(addr >= machdep->machspec->kimage_text) &&
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@@ -4562,7 +4605,10 @@ int
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arm64_IS_VMALLOC_ADDR(ulong vaddr)
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{
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struct machine_specific *ms = machdep->machspec;
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-
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+
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+ if (is_mte_kvaddr(vaddr))
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+ vaddr = mte_tag_reset(vaddr);
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+
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if ((machdep->flags & NEW_VMEMMAP) &&
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(vaddr >= machdep->machspec->kimage_text) &&
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(vaddr <= machdep->machspec->kimage_end))
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diff --git a/defs.h b/defs.h
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index 20237b72a10b..aa8eba83b7f4 100644
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--- a/defs.h
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+++ b/defs.h
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@@ -3348,6 +3348,7 @@ typedef signed int s32;
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#define FLIPPED_VM (0x400)
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#define HAS_PHYSVIRT_OFFSET (0x800)
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#define OVERFLOW_STACKS (0x1000)
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+#define ARM64_MTE (0x2000)
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/*
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* Get kimage_voffset from /dev/crash
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--
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2.41.0
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