From f4661d293eb2d01dfc742982761a36fafe456d46 Mon Sep 17 00:00:00 2001 From: Jacek Tomaka Date: Sat, 25 Aug 2018 11:50:39 +0800 Subject: [PATCH 1/3] x86/microcode: Make revision and processor flags world-readable The microcode revision is already readable for non-root users via /proc/cpuinfo. Thus, there's no reason to keep the same information readable by root only in /sys/devices/system/cpu/cpuX/microcode/. Make .../processor_flags world-readable too, while at it. Reported-by: Tim Burgess Signed-off-by: Jacek Tomaka Signed-off-by: Borislav Petkov Signed-off-by: Thomas Gleixner Link: http://lkml.kernel.org/r/20180825035039.14409-1-jacekt@dugeo.com --- arch/x86/kernel/cpu/microcode/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index b9bc8a1a584e..2637ff09d6a0 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -666,8 +666,8 @@ static ssize_t pf_show(struct device *dev, } static DEVICE_ATTR_WO(reload); -static DEVICE_ATTR(version, 0400, version_show, NULL); -static DEVICE_ATTR(processor_flags, 0400, pf_show, NULL); +static DEVICE_ATTR(version, 0444, version_show, NULL); +static DEVICE_ATTR(processor_flags, 0444, pf_show, NULL); static struct attribute *mc_default_attrs[] = { &dev_attr_version.attr, From 4a60aa05a0634241ce17f957bf9fb5ac1eed6576 Mon Sep 17 00:00:00 2001 From: Allan Xavier Date: Fri, 7 Sep 2018 08:12:01 -0500 Subject: [PATCH 2/3] objtool: Support per-function rodata sections Add support for processing switch jump tables in objects with multiple .rodata sections, such as those created by '-ffunction-sections' and '-fdata-sections'. Currently, objtool always looks in .rodata for jump table information, which results in many "sibling call from callable instruction with modified stack frame" warnings with objects compiled using those flags. The fix is comprised of three parts: 1. Flagging all .rodata sections when importing ELF information for easier checking later. 2. Keeping a reference to the section each relocation is from in order to get the list_head for the other relocations in that section. 3. Finding jump tables by following relocations to .rodata sections, rather than always referencing a single global .rodata section. The patch has been tested without data sections enabled and no differences in the resulting orc unwind information were seen. Note that as objtool adds terminators to end of each .text section the unwind information generated between a function+data sections build and a normal build aren't directly comparable. Manual inspection suggests that objtool is now generating the correct information, or at least making more of an effort to do so than it did previously. Signed-off-by: Allan Xavier Signed-off-by: Josh Poimboeuf Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com --- tools/objtool/check.c | 38 ++++++++++++++++++++++++++++++++------ tools/objtool/check.h | 4 ++-- tools/objtool/elf.c | 1 + tools/objtool/elf.h | 3 ++- 4 files changed, 37 insertions(+), 9 deletions(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 2928939b98ec..0414a0d52262 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -836,7 +836,7 @@ static int add_switch_table(struct objtool_file *file, struct instruction *insn, struct symbol *pfunc = insn->func->pfunc; unsigned int prev_offset = 0; - list_for_each_entry_from(rela, &file->rodata->rela->rela_list, list) { + list_for_each_entry_from(rela, &table->rela_sec->rela_list, list) { if (rela == next_table) break; @@ -926,6 +926,7 @@ static struct rela *find_switch_table(struct objtool_file *file, { struct rela *text_rela, *rodata_rela; struct instruction *orig_insn = insn; + struct section *rodata_sec; unsigned long table_offset; /* @@ -953,10 +954,13 @@ static struct rela *find_switch_table(struct objtool_file *file, /* look for a relocation which references .rodata */ text_rela = find_rela_by_dest_range(insn->sec, insn->offset, insn->len); - if (!text_rela || text_rela->sym != file->rodata->sym) + if (!text_rela || text_rela->sym->type != STT_SECTION || + !text_rela->sym->sec->rodata) continue; table_offset = text_rela->addend; + rodata_sec = text_rela->sym->sec; + if (text_rela->type == R_X86_64_PC32) table_offset += 4; @@ -964,10 +968,10 @@ static struct rela *find_switch_table(struct objtool_file *file, * Make sure the .rodata address isn't associated with a * symbol. gcc jump tables are anonymous data. */ - if (find_symbol_containing(file->rodata, table_offset)) + if (find_symbol_containing(rodata_sec, table_offset)) continue; - rodata_rela = find_rela_by_dest(file->rodata, table_offset); + rodata_rela = find_rela_by_dest(rodata_sec, table_offset); if (rodata_rela) { /* * Use of RIP-relative switch jumps is quite rare, and @@ -1052,7 +1056,7 @@ static int add_switch_table_alts(struct objtool_file *file) struct symbol *func; int ret; - if (!file->rodata || !file->rodata->rela) + if (!file->rodata) return 0; for_each_sec(file, sec) { @@ -1198,10 +1202,33 @@ static int read_retpoline_hints(struct objtool_file *file) return 0; } +static void mark_rodata(struct objtool_file *file) +{ + struct section *sec; + bool found = false; + + /* + * This searches for the .rodata section or multiple .rodata.func_name + * sections if -fdata-sections is being used. The .str.1.1 and .str.1.8 + * rodata sections are ignored as they don't contain jump tables. + */ + for_each_sec(file, sec) { + if (!strncmp(sec->name, ".rodata", 7) && + !strstr(sec->name, ".str1.")) { + sec->rodata = true; + found = true; + } + } + + file->rodata = found; +} + static int decode_sections(struct objtool_file *file) { int ret; + mark_rodata(file); + ret = decode_instructions(file); if (ret) return ret; @@ -2171,7 +2198,6 @@ int check(const char *_objname, bool orc) INIT_LIST_HEAD(&file.insn_list); hash_init(file.insn_hash); file.whitelist = find_section_by_name(file.elf, ".discard.func_stack_frame_non_standard"); - file.rodata = find_section_by_name(file.elf, ".rodata"); file.c_file = find_section_by_name(file.elf, ".comment"); file.ignore_unreachables = no_unreachable; file.hints = false; diff --git a/tools/objtool/check.h b/tools/objtool/check.h index 95700a2bcb7c..e6e8a655b556 100644 --- a/tools/objtool/check.h +++ b/tools/objtool/check.h @@ -60,8 +60,8 @@ struct objtool_file { struct elf *elf; struct list_head insn_list; DECLARE_HASHTABLE(insn_hash, 16); - struct section *rodata, *whitelist; - bool ignore_unreachables, c_file, hints; + struct section *whitelist; + bool ignore_unreachables, c_file, hints, rodata; }; int check(const char *objname, bool orc); diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index 7ec85d567598..f7082de1ee82 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -379,6 +379,7 @@ static int read_relas(struct elf *elf) rela->offset = rela->rela.r_offset; symndx = GELF_R_SYM(rela->rela.r_info); rela->sym = find_symbol_by_index(elf, symndx); + rela->rela_sec = sec; if (!rela->sym) { WARN("can't find rela entry symbol %d for %s", symndx, sec->name); diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h index de5cd2ddded9..bc97ed86b9cd 100644 --- a/tools/objtool/elf.h +++ b/tools/objtool/elf.h @@ -48,7 +48,7 @@ struct section { char *name; int idx; unsigned int len; - bool changed, text; + bool changed, text, rodata; }; struct symbol { @@ -68,6 +68,7 @@ struct rela { struct list_head list; struct hlist_node hash; GElf_Rela rela; + struct section *rela_sec; struct symbol *sym; unsigned int type; unsigned long offset; From d2266bbfa9e3e32e3b642965088ca461bd24a94f Mon Sep 17 00:00:00 2001 From: Feng Tang Date: Wed, 3 Oct 2018 00:49:21 +0800 Subject: [PATCH 3/3] x86/earlyprintk: Add a force option for pciserial device The "pciserial" earlyprintk variant helps much on many modern x86 platforms, but unfortunately there are still some platforms with PCI UART devices which have the wrong PCI class code. In that case, the current class code check does not allow for them to be used for logging. Add a sub-option "force" which overrides the class code check and thus the use of such device can be enforced. [ bp: massage formulations. ] Suggested-by: Borislav Petkov Signed-off-by: Feng Tang Signed-off-by: Borislav Petkov Cc: "H. Peter Anvin" Cc: "Stuart R . Anderson" Cc: Bjorn Helgaas Cc: David Rientjes Cc: Feng Tang Cc: Frederic Weisbecker Cc: Greg Kroah-Hartman Cc: H Peter Anvin Cc: Ingo Molnar Cc: Jiri Kosina Cc: Jonathan Corbet Cc: Kai-Heng Feng Cc: Kate Stewart Cc: Konrad Rzeszutek Wilk Cc: Peter Zijlstra Cc: Philippe Ombredanne Cc: Thomas Gleixner Cc: Thymo van Beers Cc: alan@linux.intel.com Cc: linux-doc@vger.kernel.org Link: http://lkml.kernel.org/r/20181002164921.25833-1-feng.tang@intel.com --- .../admin-guide/kernel-parameters.txt | 6 +++- arch/x86/kernel/early_printk.c | 29 ++++++++++++------- 2 files changed, 24 insertions(+), 11 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 92eb1f42240d..34e6800dea0e 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1063,7 +1063,7 @@ earlyprintk=serial[,0x...[,baudrate]] earlyprintk=ttySn[,baudrate] earlyprintk=dbgp[debugController#] - earlyprintk=pciserial,bus:device.function[,baudrate] + earlyprintk=pciserial[,force],bus:device.function[,baudrate] earlyprintk=xdbc[xhciController#] earlyprintk is useful when the kernel crashes before @@ -1095,6 +1095,10 @@ The sclp output can only be used on s390. + The optional "force" to "pciserial" enables use of a + PCI device even when its classcode is not of the + UART class. + edac_report= [HW,EDAC] Control how to report EDAC event Format: {"on" | "off" | "force"} on: enable EDAC to report H/W event. May be overridden diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c index 5e801c8c8ce7..374a52fa5296 100644 --- a/arch/x86/kernel/early_printk.c +++ b/arch/x86/kernel/early_printk.c @@ -213,8 +213,9 @@ static unsigned int mem32_serial_in(unsigned long addr, int offset) * early_pci_serial_init() * * This function is invoked when the early_printk param starts with "pciserial" - * The rest of the param should be ",B:D.F,baud" where B, D & F describe the - * location of a PCI device that must be a UART device. + * The rest of the param should be "[force],B:D.F,baud", where B, D & F describe + * the location of a PCI device that must be a UART device. "force" is optional + * and overrides the use of an UART device with a wrong PCI class code. */ static __init void early_pci_serial_init(char *s) { @@ -224,17 +225,23 @@ static __init void early_pci_serial_init(char *s) u32 classcode, bar0; u16 cmdreg; char *e; + int force = 0; - - /* - * First, part the param to get the BDF values - */ if (*s == ',') ++s; if (*s == 0) return; + /* Force the use of an UART device with wrong class code */ + if (!strncmp(s, "force,", 6)) { + force = 1; + s += 6; + } + + /* + * Part the param to get the BDF values + */ bus = (u8)simple_strtoul(s, &e, 16); s = e; if (*s != ':') @@ -253,7 +260,7 @@ static __init void early_pci_serial_init(char *s) s++; /* - * Second, find the device from the BDF + * Find the device from the BDF */ cmdreg = read_pci_config(bus, slot, func, PCI_COMMAND); classcode = read_pci_config(bus, slot, func, PCI_CLASS_REVISION); @@ -264,8 +271,10 @@ static __init void early_pci_serial_init(char *s) */ if (((classcode >> 16 != PCI_CLASS_COMMUNICATION_MODEM) && (classcode >> 16 != PCI_CLASS_COMMUNICATION_SERIAL)) || - (((classcode >> 8) & 0xff) != 0x02)) /* 16550 I/F at BAR0 */ - return; + (((classcode >> 8) & 0xff) != 0x02)) /* 16550 I/F at BAR0 */ { + if (!force) + return; + } /* * Determine if it is IO or memory mapped @@ -289,7 +298,7 @@ static __init void early_pci_serial_init(char *s) } /* - * Lastly, initialize the hardware + * Initialize the hardware */ if (*s) { if (strcmp(s, "nocfg") == 0)