From nobody Tue Sep 16 15:59:42 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CD8D6C4167B for ; Sat, 31 Dec 2022 17:14:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232273AbiLaROO (ORCPT ); Sat, 31 Dec 2022 12:14:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229595AbiLaROL (ORCPT ); Sat, 31 Dec 2022 12:14:11 -0500 Received: from mail-pg1-x52b.google.com (mail-pg1-x52b.google.com [IPv6:2607:f8b0:4864:20::52b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9C5EA2AE for ; Sat, 31 Dec 2022 09:14:09 -0800 (PST) Received: by mail-pg1-x52b.google.com with SMTP id d10so15947710pgm.13 for ; Sat, 31 Dec 2022 09:14:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=references:in-reply-to:message-id:date:subject:cc:to:from:from:to :cc:subject:date:message-id:reply-to; bh=pBJs4mY/D+ZwJGNCJVKUlWrXepuhs6bh7m8A/RKMgZg=; b=ka+ONasPV0NGAT+kb7L1DOdLyCVQh4HVEjdaHNBXYSq2jVz1ayF++MXNeKTy+oHITx /uNnLMQEf0yv16DuHZ51gK1GC96S1q1IOw7nnRtYST41tc0EALiD41sXrK4h+8PAlh7O t0W3N9T3pUMGz5MzIl7uCWzevzeRxt747jiQuKshFYnS3BqCBFKXfBly9vLZIve6IuZm 1JUhprooq7LbTJSH5fJCZgyS4ahdMel/iRm+P+OT7tA9ZpMO87uXW3It51DXe/dLUcqQ DgOOwFTFGfgV/Tt7FMpVOqpPZFtGjkGWKIt8jRWSEV/sR0oD+pIQ4s8qhj1OyKrwz6y6 EXHw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=references:in-reply-to:message-id:date:subject:cc:to:from :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=pBJs4mY/D+ZwJGNCJVKUlWrXepuhs6bh7m8A/RKMgZg=; b=etgNzmAwlNLIY8s9Xqh4MzCbCfqBWLE8viFFTxcfBq00lrIXXg38WmxsqnDa0HC8lo D24D895p+jhrPvZhbrQFCprbUhF9vpvDlR8Uwmex7DOIT3dYgUO+BmOrtZK19MfW0aN4 X92h3b2g//ITwaYcxO2rQuOKWQLfv7AJhxkFMnI5gPvRoam4XsfjxCf3HR9BltaynILy 9hvmlsfzWmMzngh/y0xaEOngt97euFHQCx1dU6btMdrtm7VPZvdfN4ZsG4dQTyrGq7MF wWjajFGoOkSM4VoqnJnXa49cMSscgrcE0MEmNFW5I7VaYlujq3ncivrHe/RRE/H49LAR 6oAQ== X-Gm-Message-State: AFqh2koGFoTw9/NKs0J63CLbHF7wZOmQIBiCAWZL7VPyePm4iQy7zu83 d14l6KohQb6VghxlyPqkaLI= X-Google-Smtp-Source: AMrXdXsS5UhCBnOcrKq75pm+buUGEr+RDiMV7xv5jnU2Lw7TCPP7uOcUqr+8ZajEPTzjACkzWiY8Uw== X-Received: by 2002:aa7:99ce:0:b0:582:243c:49c9 with SMTP id v14-20020aa799ce000000b00582243c49c9mr3403194pfi.28.1672506848896; Sat, 31 Dec 2022 09:14:08 -0800 (PST) Received: from localhost.localdomain ([116.58.254.36]) by smtp.gmail.com with ESMTPSA id f26-20020aa7969a000000b0058103f45d9esm9033091pfk.82.2022.12.31.09.14.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 31 Dec 2022 09:14:08 -0800 (PST) From: Dmitrii Bundin To: dmitrii.bundin.a@gmail.com Cc: akpm@linux-foundation.org, gregkh@linuxfoundation.org, jan.kiszka@siemens.com, kbingham@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mingo@redhat.com, vbabka@suse.cz, x86@kernel.org Subject: [PATCH v2] scripts/gdb: add mm introspection utils Date: Sat, 31 Dec 2022 20:12:58 +0300 Message-Id: <20221231171258.7907-1-dmitrii.bundin.a@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20221230163512.23736-1-dmitrii.bundin.a@gmail.com> References: <20221230163512.23736-1-dmitrii.bundin.a@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" This command provides a way to traverse the entire page hierarchy by a given virtual address on x86. In addition to qemu's commands info tlb/info mem it provides the complete information about the paging structure for an arbitrary virtual address. It supports 4KB/2MB/1GB and 5 level paging. Here is an example output for 2MB success translation: (gdb) translate-vm address CR3: CR3 BINARY DATA: 0x10c1d2002 NEXT ENTRY PHYSICALL ADDRESS: 0x10c1d2000 --- PAGE LEVEL WRITE THROUGH(bit 3): False PAGE LEVEL CACHE DISABLED(bit 4): False LEVEL 4: ENTRY ADDRESS: 0xffff88810c1d27f0 PAGE ENTRY BINARY DATA: 0x8000000105dca067 NEXT ENTRY PHYSICALL ADDRESS: 0x105dca000 --- ENTRY PRESENT(bit 0): True READ/WRITE ACCESS ALLOWED(bit 1): True USER ACCESS ALLOWED(bit 2): True PAGE LEVEL WRITE THROUGH(bit 3): False PAGE LEVEL CACHE DISABLED(bit 4): False ENTRY HAS BEEN ACCESSED(bit 5): True PAGE SIZE(bit 7): False RESTART TO ORDINARY(bit 11): False EXECUTE DISABLE(bit 63): True LEVEL 3: ENTRY ADDRESS: 0xffff888105dca9d0 PAGE ENTRY BINARY DATA: 0x105c87067 NEXT ENTRY PHYSICALL ADDRESS: 0x105c87000 --- ENTRY PRESENT(bit 0): True READ/WRITE ACCESS ALLOWED(bit 1): True USER ACCESS ALLOWED(bit 2): True PAGE LEVEL WRITE THROUGH(bit 3): False PAGE LEVEL CACHE DISABLED(bit 4): False ENTRY HAS BEEN ACCESSED(bit 5): True PAGE SIZE(bit 7): False RESTART TO ORDINARY(bit 11): False EXECUTE DISABLE(bit 63): False LEVEL 2: ENTRY ADDRESS: 0xffff888105c87698 PAGE ENTRY BINARY DATA: 0x80000001622008e7 PAGE SIZE: 2MB PAGE PHYSICALL ADDRESS: 0x162200000 --- ENTRY PRESENT(bit 0): True READ/WRITE ACCESS ALLOWED(bit 1): True USER ACCESS ALLOWED(bit 2): True PAGE LEVEL WRITE THROUGH(bit 3): False PAGE LEVEL CACHE DISABLED(bit 4): False ENTRY HAS BEEN ACCESSED(bit 5): True PAGE DIRTY(bit 6): True PAGE SIZE(bit 7): True GLOBAL TRANSLATION(bit 8): False RESTART TO ORDINARY(bit 11): True PAT(bit 12): False PROTECTION KEY(bits (62, 59)): 0 EXECUTE DISABLE(bit 63): True Signed-off-by: Dmitrii Bundin --- Changes in v2: https://lore.kernel.org/all/20221230163512.23736-1-dmitrii.b= undin.a@gmail.com/ - Fix commit message to mention x86 explicitly - Assign page_offset_base to a constant in case CONFIG_DYNAMIC_MEMORY_LAYOUT is disabled scripts/gdb/linux/mm.py | 222 +++++++++++++++++++++++++++++++++++++ scripts/gdb/vmlinux-gdb.py | 1 + 2 files changed, 223 insertions(+) create mode 100644 scripts/gdb/linux/mm.py diff --git a/scripts/gdb/linux/mm.py b/scripts/gdb/linux/mm.py new file mode 100644 index 000000000000..1b1d59872b25 --- /dev/null +++ b/scripts/gdb/linux/mm.py @@ -0,0 +1,222 @@ +# +# gdb helper commands and functions for Linux kernel debugging +# +# routines to introspect page table +# +# Authors: +# Dmitrii Bundin +# +# This work is licensed under the terms of the GNU GPL version 2. +# + +import gdb + +from linux import utils + +PHYSICAL_ADDRESS_MASK =3D gdb.parse_and_eval('0xfffffffffffff') + + +def page_mask(level=3D1): + # 4KB + if level =3D=3D 1: + return gdb.parse_and_eval('(u64) ~0xfff') + # 2MB + elif level =3D=3D 2: + return gdb.parse_and_eval('(u64) ~0x1fffff') + # 1GB + elif level =3D=3D 3: + return gdb.parse_and_eval('(u64) ~0x3fffffff') + else: + raise Exception(f'Unknown page level: {level}') + + +#page_offset_base in case CONFIG_DYNAMIC_MEMORY_LAYOUT is disabled +POB_NO_DYNAMIC_MEM_LAYOUT =3D '0xffff888000000000' +def _page_offset_base(): + pob_symbol =3D gdb.lookup_global_symbol('page_offset_base') + pob =3D pob_symbol.name if pob_symbol else POB_NO_DYNAMIC_MEM_LAYOUT + return gdb.parse_and_eval(pob) + + +def is_bit_defined_tupled(data, offset): + return offset, bool(data >> offset & 1) + +def content_tupled(data, bit_start, bit_end): + return (bit_end, bit_start), data >> bit_start & ((1 << (1 + bit_end -= bit_start)) - 1) + +def entry_va(level, phys_addr, translating_va): + def start_bit(level): + if level =3D=3D 5: + return 48 + elif level =3D=3D 4: + return 39 + elif level =3D=3D 3: + return 30 + elif level =3D=3D 2: + return 21 + elif level =3D=3D 1: + return 12 + else: + raise Exception(f'Unknown level {level}') + + entry_offset =3D ((translating_va >> start_bit(level)) & 511) * 8 + entry_va =3D _page_offset_base() + phys_addr + entry_offset + return entry_va + +class Cr3(): + def __init__(self, cr3, page_levels): + self.cr3 =3D cr3 + self.page_levels =3D page_levels + self.page_level_write_through =3D is_bit_defined_tupled(cr3, 3) + self.page_level_cache_disabled =3D is_bit_defined_tupled(cr3, 4) + self.next_entry_physical_address =3D cr3 & PHYSICAL_ADDRESS_MASK &= page_mask() + + def next_entry(self, va): + next_level =3D self.page_levels + return PageHierarchyEntry(entry_va(next_level, self.next_entry_phy= sical_address, va), next_level) + + def mk_string(self): + return f"""\ +CR3: + CR3 BINARY DATA: {hex(self.cr3)} + NEXT ENTRY PHYSICALL ADDRESS: {hex(self.next_entry_physical_address)} + --- + PAGE LEVEL WRITE THROUGH(bit {self.page_level_write_through[0]}): {sel= f.page_level_write_through[1]} + PAGE LEVEL CACHE DISABLED(bit {self.page_level_cache_disabled[0]}): {s= elf.page_level_cache_disabled[1]} +""" + + +class PageHierarchyEntry(): + def __init__(self, address, level): + data =3D int.from_bytes( + memoryview(gdb.selected_inferior().read_memory(address, 8)), + "little" + ) + if level =3D=3D 1: + self.is_page =3D True + self.entry_present =3D is_bit_defined_tupled(data, 0) + self.read_write =3D is_bit_defined_tupled(data, 1) + self.user_access_allowed =3D is_bit_defined_tupled(data, 2) + self.page_level_write_through =3D is_bit_defined_tupled(data, = 3) + self.page_level_cache_disabled =3D is_bit_defined_tupled(data,= 4) + self.entry_was_accessed =3D is_bit_defined_tupled(data, 5) + self.dirty =3D is_bit_defined_tupled(data, 6) + self.pat =3D is_bit_defined_tupled(data, 7) + self.global_translation =3D is_bit_defined_tupled(data, 8) + self.page_physical_address =3D data & PHYSICAL_ADDRESS_MASK & = page_mask(level) + self.next_entry_physical_address =3D None + self.hlat_restart_with_ordinary =3D is_bit_defined_tupled(data= , 11) + self.protection_key =3D content_tupled(data, 59, 62) + self.executed_disable =3D is_bit_defined_tupled(data, 63) + else: + page_size =3D is_bit_defined_tupled(data, 7) + page_size_bit =3D page_size[1] + self.is_page =3D page_size_bit + self.entry_present =3D is_bit_defined_tupled(data, 0) + self.read_write =3D is_bit_defined_tupled(data, 1) + self.user_access_allowed =3D is_bit_defined_tupled(data, 2) + self.page_level_write_through =3D is_bit_defined_tupled(data, = 3) + self.page_level_cache_disabled =3D is_bit_defined_tupled(data,= 4) + self.entry_was_accessed =3D is_bit_defined_tupled(data, 5) + self.page_size =3D page_size + self.dirty =3D is_bit_defined_tupled( + data, 6) if page_size_bit else None + self.global_translation =3D is_bit_defined_tupled( + data, 8) if page_size_bit else None + self.pat =3D is_bit_defined_tupled( + data, 12) if page_size_bit else None + self.page_physical_address =3D data & PHYSICAL_ADDRESS_MASK & = page_mask(level) if page_size_bit else None + self.next_entry_physical_address =3D None if page_size_bit els= e data & PHYSICAL_ADDRESS_MASK & page_mask() + self.hlat_restart_with_ordinary =3D is_bit_defined_tupled(data= , 11) + self.protection_key =3D content_tupled(data, 59, 62) if page_s= ize_bit else None + self.executed_disable =3D is_bit_defined_tupled(data, 63) + self.address =3D address + self.page_entry_binary_data =3D data + self.page_hierarchy_level =3D level + + def next_entry(self, va): + if self.is_page or not self.entry_present[1]: + return None + + next_level =3D self.page_hierarchy_level - 1 + return PageHierarchyEntry(entry_va(next_level, self.next_entry_phy= sical_address, va), next_level) + + + def mk_string(self): + if not self.entry_present[1]: + return f"""\ +LEVEL {self.page_hierarchy_level}: + ENTRY ADDRESS: {hex(self.address)} + PAGE ENTRY BINARY DATA: {hex(self.page_entry_binary_data)} + --- + PAGE ENTRY IS NOT PRESENT! +""" + elif self.is_page: + return f"""\ +LEVEL {self.page_hierarchy_level}: + ENTRY ADDRESS: {hex(self.address)} + PAGE ENTRY BINARY DATA: {hex(self.page_entry_binary_data)} + PAGE SIZE: {'1GB' if self.page_hierarchy_level =3D=3D 3 else '2MB' if = self.page_hierarchy_level =3D=3D 2 else '4KB' if self.page_hierarchy_level = =3D=3D 1 else 'Unknown page size for level:' + self.page_hierarchy_level} + PAGE PHYSICALL ADDRESS: {hex(self.page_physical_address)} + --- + ENTRY PRESENT(bit {self.entry_present[0]}): {self.entry_present[1= ]} + READ/WRITE ACCESS ALLOWED(bit {self.read_write[0]}): {self.read_write[= 1]} + USER ACCESS ALLOWED(bit {self.user_access_allowed[0]}): {self.user_acc= ess_allowed[1]} + PAGE LEVEL WRITE THROUGH(bit {self.page_level_write_through[0]}): {sel= f.page_level_write_through[1]} + PAGE LEVEL CACHE DISABLED(bit {self.page_level_cache_disabled[0]}): {s= elf.page_level_cache_disabled[1]} + ENTRY HAS BEEN ACCESSED(bit {self.entry_was_accessed[0]}): {self.entry= _was_accessed[1]} + PAGE DIRTY(bit {self.dirty[0]}): {self.dirty[1]} + """ + \ + ("" if self.page_hierarchy_level =3D=3D 1 else f"""PAGE SIZE(bit {self= .page_size[0]}): {self.page_size[1]} + """) + \ + f"""GLOBAL TRANSLATION(bit {self.global_translation[0]}): {self.global= _translation[1]} + RESTART TO ORDINARY(bit {self.hlat_restart_with_ordinary[0]}): {self.h= lat_restart_with_ordinary[1]} + PAT(bit {self.pat[0]}): {self.pat[1]} + PROTECTION KEY(bits {self.protection_key[0]}): {self.protection_key[1]} + EXECUTE DISABLE(bit {self.executed_disable[0]}): {self.executed_disabl= e[1]} +""" + else: + return f"""\ +LEVEL {self.page_hierarchy_level}: + ENTRY ADDRESS: {hex(self.address)} + PAGE ENTRY BINARY DATA: {hex(self.page_entry_binary_data)} + NEXT ENTRY PHYSICALL ADDRESS: {hex(self.next_entry_physical_address)} + --- + ENTRY PRESENT(bit {self.entry_present[0]}): {self.entry_present[1= ]} + READ/WRITE ACCESS ALLOWED(bit {self.read_write[0]}): {self.read_write[= 1]} + USER ACCESS ALLOWED(bit {self.user_access_allowed[0]}): {self.user_acc= ess_allowed[1]} + PAGE LEVEL WRITE THROUGH(bit {self.page_level_write_through[0]}): {sel= f.page_level_write_through[1]} + PAGE LEVEL CACHE DISABLED(bit {self.page_level_cache_disabled[0]}): {s= elf.page_level_cache_disabled[1]} + ENTRY HAS BEEN ACCESSED(bit {self.entry_was_accessed[0]}): {self.entry= _was_accessed[1]} + PAGE SIZE(bit {self.page_size[0]}): {self.page_size[1]} + RESTART TO ORDINARY(bit {self.hlat_restart_with_ordinary[0]}): {self.h= lat_restart_with_ordinary[1]} + EXECUTE DISABLE(bit {self.executed_disable[0]}): {self.executed_disabl= e[1]} +""" + + +class TranslateVM(gdb.Command): + """Prints the entire paging structure used to translate a given virtua= l address. + +Having an address space of the currently executed process translates the v= irtual address +and prints detailed information of all paging structure levels used for th= e transaltion.""" + + def __init__(self): + super(TranslateVM, self).__init__('translate-vm', gdb.COMMAND_USER) + + def invoke(self, arg, from_tty): + if utils.is_target_arch("x86"): + vm_address =3D gdb.parse_and_eval(f'{arg}') + cr3_data =3D gdb.parse_and_eval('$cr3') + cr4 =3D gdb.parse_and_eval('$cr4') + page_levels =3D 5 if cr4 & (1 << 12) else 4 + page_entry =3D Cr3(cr3_data, page_levels) + while page_entry: + gdb.write(page_entry.mk_string()) + page_entry =3D page_entry.next_entry(vm_address) + else: + gdb.GdbError("Virtual address translation is not" + "supported for this arch") + + + +TranslateVM() diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py index 4136dc2c59df..27bd7339bccc 100644 --- a/scripts/gdb/vmlinux-gdb.py +++ b/scripts/gdb/vmlinux-gdb.py @@ -37,3 +37,4 @@ else: import linux.clk import linux.genpd import linux.device + import linux.mm --=20 2.17.1