- 08 Nov, 2017 13 commits
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Ricardo Neri authored
The STR and SLDT instructions are not valid when running on virtual-8086 mode and generate an invalid operand exception. These two instructions are protected by the Intel User-Mode Instruction Prevention (UMIP) security feature. In protected mode, if UMIP is enabled, these instructions generate a general protection fault if called from CPL > 0. Linux traps the general protection fault and emulates the instructions sgdt, sidt and smsw; but not str and sldt. These tests are added to verify that the emulation code does not emulate these two instructions but the expected invalid operand exception is seen. Tests fallback to exit with INT3 in case emulation does happen. Signed-off-by:
Ricardo Neri <ricardo.neri-calderon@linux.intel.com> Reviewed-by:
Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Chen Yucong <slaoub@gmail.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Huang Rui <ray.huang@amd.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi V. Shankar <ravi.v.shankar@intel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: ricardo.neri@intel.com Link: http://lkml.kernel.org/r/1509935277-22138-13-git-send-email-ricardo.neri-calderon@linux.intel.comSigned-off-by:
Ingo Molnar <mingo@kernel.org>
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Ricardo Neri authored
Certain user space programs that run on virtual-8086 mode may utilize instructions protected by the User-Mode Instruction Prevention (UMIP) security feature present in new Intel processors: SGDT, SIDT and SMSW. In such a case, a general protection fault is issued if UMIP is enabled. When such a fault happens, the kernel traps it and emulates the results of these instructions with dummy values. The purpose of this new test is to verify whether the impacted instructions can be executed without causing such #GP. If no #GP exceptions occur, we expect to exit virtual-8086 mode from INT3. The instructions protected by UMIP are executed in representative use cases: a) displacement-only memory addressing b) register-indirect memory addressing c) results stored directly in operands Unfortunately, it is not possible to check the results against a set of expected values because no emulation will occur in systems that do not have the UMIP feature. Instead, results are printed for verification. A simple verification is done to ensure that results of all tests are identical. Signed-off-by:
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Ricardo Neri authored
If the User-Mode Instruction Prevention CPU feature is available and enabled, a general protection fault will be issued if the instructions sgdt, sldt, sidt, str or smsw are executed from user-mode context (CPL > 0). If the fault was caused by any of the instructions protected by UMIP, fixup_umip_exception() will emulate dummy results for these instructions as follows: in virtual-8086 and protected modes, sgdt, sidt and smsw are emulated; str and sldt are not emulated. No emulation is done for user-space long mode processes. If emulation is successful, the emulated result is passed to the user space program and no SIGSEGV signal is emitted. Signed-off-by:
Andy Lutomirski <luto@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Chen Yucong <slaoub@gmail.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Huang Rui <ray.huang@amd.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi V. Shankar <ravi.v.shankar@intel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: ricardo.neri@intel.com Link: http://lkml.kernel.org/r/1509935277-22138-11-git-send-email-ricardo.neri-calderon@linux.intel.com [ Added curly braces. ] Signed-off-by:
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Ricardo Neri authored
User-Mode Instruction Prevention (UMIP) is enabled by setting/clearing a bit in %cr4. It makes sense to enable UMIP at some point while booting, before user spaces come up. Like SMAP and SMEP, is not critical to have it enabled very early during boot. This is because UMIP is relevant only when there is a user space to be protected from. Given these similarities, UMIP can be enabled along with SMAP and SMEP. At the moment, UMIP is disabled by default at build time. It can be enabled at build time by selecting CONFIG_X86_INTEL_UMIP. If enabled at build time, it can be disabled at run time by adding clearcpuid=514 to the kernel parameters. Signed-off-by:
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Ricardo Neri authored
fixup_umip_exception() will be called from do_general_protection(). If the former returns false, the latter will issue a SIGSEGV with SEND_SIG_PRIV. However, when emulation is successful but the emulated result cannot be copied to user space memory, it is more accurate to issue a SIGSEGV with SEGV_MAPERR with the offending address. A new function, inspired in force_sig_info_fault(), is introduced to model the page fault. Signed-off-by:
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Ricardo Neri authored
The feature User-Mode Instruction Prevention present in recent Intel processor prevents a group of instructions (sgdt, sidt, sldt, smsw, and str) from being executed with CPL > 0. Otherwise, a general protection fault is issued. Rather than relaying to the user space the general protection fault caused by the UMIP-protected instructions (in the form of a SIGSEGV signal), it can be trapped and the instruction emulated to provide a dummy result. This allows to both conserve the current kernel behavior and not reveal the system resources that UMIP intends to protect (i.e., the locations of the global descriptor and interrupt descriptor tables, the segment selectors of the local descriptor table, the value of the task state register and the contents of the CR0 register). This emulation is needed because certain applications (e.g., WineHQ and DOSEMU2) rely on this subset of instructions to function. Given that sldt and str are not commonly used in programs that run on WineHQ or DOSEMU2, they are not emulated. Also, emulation is provided only for 32-bit processes; 64-bit processes that attempt to use the instructions that UMIP protects will receive the SIGSEGV signal issued as a consequence of the general protection fault. The instructions protected by UMIP can be split in two groups. Those which return a kernel memory address (sgdt and sidt) and those which return a value (smsw, sldt and str; the last two not emulated). For the instructions that return a kernel memory address, applications such as WineHQ rely on the result being located in the kernel memory space, not the actual location of the table. The result is emulated as a hard-coded value that lies close to the top of the kernel memory. The limit for the GDT and the IDT are set to zero. The instruction smsw is emulated to return the value that the register CR0 has at boot time as set in the head_32. Care is taken to appropriately emulate the results when segmentation is used. That is, rather than relying on USER_DS and USER_CS, the function insn_get_addr_ref() inspects the segment descriptor pointed by the registers in pt_regs. This ensures that we correctly obtain the segment base address and the address and operand sizes even if the user space application uses a local descriptor table. Signed-off-by:
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Ricardo Neri authored
User-Mode Instruction Prevention is a security feature present in new Intel processors that, when set, prevents the execution of a subset of instructions if such instructions are executed in user mode (CPL > 0). Attempting to execute such instructions causes a general protection exception. The subset of instructions comprises: * SGDT - Store Global Descriptor Table * SIDT - Store Interrupt Descriptor Table * SLDT - Store Local Descriptor Table * SMSW - Store Machine Status Word * STR - Store Task Register This feature is also added to the list of disabled-features to allow a cleaner handling of build-time configuration. Signed-off-by:
Borislav Petkov <bp@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Chen Yucong <slaoub@gmail.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Huang Rui <ray.huang@amd.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi V. Shankar <ravi.v.shankar@intel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: ricardo.neri@intel.com Link: http://lkml.kernel.org/r/1509935277-22138-7-git-send-email-ricardo.neri-calderon@linux.intel.comSigned-off-by:
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Ricardo Neri authored
Tasks running in virtual-8086 mode, in protected mode with code segment descriptors that specify 16-bit default address sizes via the D bit, or via an address override prefix will use 16-bit addressing form encodings as described in the Intel 64 and IA-32 Architecture Software Developer's Manual Volume 2A Section 2.1.5, Table 2-1. 16-bit addressing encodings differ in several ways from the 32-bit/64-bit addressing form encodings: ModRM.rm points to different registers and, in some cases, effective addresses are indicated by the addition of the value of two registers. Also, there is no support for SIB bytes. Thus, a separate function is needed to parse this form of addressing. Three functions are introduced. get_reg_offset_16() obtains the offset from the base of pt_regs of the registers indicated by the ModRM byte of the address encoding. get_eff_addr_modrm_16() computes the effective address from the value of the register operands. get_addr_ref_16() computes the linear address using the obtained effective address and the base address of the segment. Segment limits are enforced when running in protected mode. Signed-off-by:
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Ricardo Neri authored
It is possible to utilize 32-bit address encodings in virtual-8086 mode via an address override instruction prefix. However, the range of the effective address is still limited to [0x-0xffff]. In such a case, return error. Also, linear addresses in virtual-8086 mode are limited to 20 bits. Enforce such limit by truncating the most significant bytes of the computed linear address. Signed-off-by:
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Ricardo Neri authored
The function insn_get_addr_ref() is capable of handling only 64-bit addresses. A previous commit introduced a function to handle 32-bit addresses. Invoke these two functions from a third wrapper function that calls the appropriate routine based on the address size specified in the instruction structure (obtained by looking at the code segment default address size and the address override prefix, if present). While doing this, rename the original function insn_get_addr_ref() with the more appropriate name get_addr_ref_64(), ensure it is only used for 64-bit addresses. Also, since 64-bit addresses are not possible in 32-bit builds, provide a dummy function such case. Signed-off-by:
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Ricardo Neri authored
32-bit and 64-bit address encodings are identical. Thus, the same logic could be used to resolve the effective address. However, there are two key differences: address size and enforcement of segment limits. If running a 32-bit process on a 64-bit kernel, it is best to perform the address calculation using 32-bit data types. In this manner hardware is used for the arithmetic, including handling of signs and overflows. 32-bit addresses are generally used in protected mode; segment limits are enforced in this mode. This implementation obtains the limit of the segment associated with the instruction operands and prefixes. If the computed address is outside the segment limits, an error is returned. It is also possible to use 32-bit address in long mode and virtual-8086 mode by using an address override prefix. In such cases, segment limits are not enforced. Support to use 32-bit arithmetic is added to the utility functions that compute effective addresses. However, the end result is stored in a variable of type long (which has a width of 8 bytes in 64-bit builds). Hence, once a 32-bit effective address is computed, the 4 most significant bytes are masked out to avoid sign extension. The newly added function get_addr_ref_32() is almost identical to the existing function insn_get_addr_ref() (used for 64-bit addresses). The only difference is that it verifies that the effective address is within the limits of the segment. Signed-off-by:
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Ricardo Neri authored
Computing a linear address involves several steps. The first step is to compute the effective address. This requires determining the addressing mode in use and perform arithmetic operations on the operands. Plus, each addressing mode has special cases that must be handled. Once the effective address is known, the base address of the applicable segment is added to obtain the linear address. Clearly, this is too much work for a single function. Instead, handle each addressing mode in a separate utility function. This improves readability and gives us the opportunity to handler errors better. At the moment, arithmetic to compute the effective address uses 64-byte variables. Thus, limit support to 64-bit addresses. While reworking the function insn_get_addr_ref(), the variable addr_offset is renamed as regoff to reflect its actual use (i.e., offset, from the base of pt_regs, of the register used as operand). Suggested-by:
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Ingo Molnar authored
The UMIP series is based on top of changes already queued up in the x86/mpx branch, so merge it. Signed-off-by:
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- 07 Nov, 2017 27 commits
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kbuild test robot authored
arch/x86/kernel/crash.c:627:34-37: ERROR: Missing resource_size with res arch/x86/kernel/crash.c:528:16-19: ERROR: Missing resource_size with res Use resource_size function on resource object instead of explicit computation. Generated by: scripts/coccinelle/api/resource_size.cocci Fixes: 1d2e733b ("resource: Provide resource struct in resource walk callback") Signed-off-by:
Fengguang Wu <fengguang.wu@intel.com> Signed-off-by:
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Brijesh Singh authored
The guest physical memory area holding the struct pvclock_wall_clock and struct pvclock_vcpu_time_info are shared with the hypervisor. It periodically updates the contents of the memory. When SEV is active, the encryption attributes from the shared memory pages must be cleared so that both hypervisor and guest can access the data. Signed-off-by:
Brijesh Singh <brijesh.singh@amd.com> Signed-off-by:
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Brijesh Singh authored
When SEV is active, guest memory is encrypted with a guest-specific key, a guest memory region shared with the hypervisor must be mapped as decrypted before it can be shared. Signed-off-by:
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Brijesh Singh authored
KVM guest defines three per-CPU variables (steal-time, apf_reason, and kvm_pic_eoi) which are shared between a guest and a hypervisor. When SEV is active, memory is encrypted with a guest-specific key, and if the guest OS wants to share the memory region with the hypervisor then it must clear the C-bit (i.e set decrypted) before sharing it. DEFINE_PER_CPU_DECRYPTED can be used to define the per-CPU variables which will be shared between a guest and a hypervisor. Signed-off-by:
Tejun Heo <tj@kernel.org> Reviewed-by:
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Brijesh Singh authored
Some KVM-specific custom MSRs share the guest physical address with the hypervisor in early boot. When SEV is active, the shared physical address must be mapped with memory encryption attribute cleared so that both hypervisor and guest can access the data. Add APIs to change the memory encryption attribute in early boot code. Signed-off-by:
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Tom Lendacky authored
Secure Encrypted Virtualization (SEV) does not support string I/O, so unroll the string I/O operation into a loop operating on one element at a time. [ tglx: Gave the static key a real name instead of the obscure __sev ] Signed-off-by:
Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by:
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Tom Lendacky authored
Early in the boot process, add checks to determine if the kernel is running with Secure Encrypted Virtualization (SEV) active. Checking for SEV requires checking that the kernel is running under a hypervisor (CPUID 0x00000001, bit 31), that the SEV feature is available (CPUID 0x8000001f, bit 1) and then checking a non-interceptable SEV MSR (0xc0010131, bit 0). This check is required so that during early compressed kernel booting the pagetables (both the boot pagetables and KASLR pagetables (if enabled) are updated to include the encryption mask so that when the kernel is decompressed into encrypted memory, it can boot properly. After the kernel is decompressed and continues booting the same logic is used to check if SEV is active and set a flag indicating so. This allows to distinguish between SME and SEV, each of which have unique differences in how certain things are handled: e.g. DMA (always bounce buffered with SEV) or EFI tables (always access decrypted with SME). Signed-off-by:
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Tom Lendacky authored
DMA access to encrypted memory cannot be performed when SEV is active. In order for DMA to properly work when SEV is active, the SWIOTLB bounce buffers must be used. Signed-off-by:
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Tom Lendacky authored
In order for memory pages to be properly mapped when SEV is active, it's necessary to use the PAGE_KERNEL protection attribute as the base protection. This ensures that memory mapping of, e.g. ACPI tables, receives the proper mapping attributes. Signed-off-by:
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Tom Lendacky authored
In preperation for a new function that will need additional resource information during the resource walk, update the resource walk callback to pass the resource structure. Since the current callback start and end arguments are pulled from the resource structure, the callback functions can obtain them from the resource structure directly. Signed-off-by:
Kees Cook <keescook@chromium.org> Reviewed-by:
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Tom Lendacky authored
The walk_iomem_res_desc(), walk_system_ram_res() and walk_system_ram_range() functions each have much of the same code. Create a new function that consolidates the common code from these functions in one place to reduce the amount of duplicated code. Signed-off-by:
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Tom Lendacky authored
EFI data is encrypted when the kernel is run under SEV. Update the page table references to be sure the EFI memory areas are accessed encrypted. Signed-off-by:
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Tom Lendacky authored
The current code checks only for sme_active() when determining whether to perform the encryption attribute change. Include sev_active() in this check so that memory attribute changes can occur under SME and SEV. Signed-off-by:
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Tom Lendacky authored
When Secure Encrypted Virtualization (SEV) is active, boot data (such as EFI related data, setup data) is encrypted and needs to be accessed as such when mapped. Update the architecture override in early_memremap to keep the encryption attribute when mapping this data. Signed-off-by:
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Tom Lendacky authored
When SEV is active the trampoline area will need to be in encrypted memory so only mark the area decrypted if SME is active. Signed-off-by:
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Tom Lendacky authored
When SEV is active the initrd/initramfs will already have already been placed in memory encrypted so do not try to encrypt it. Signed-off-by:
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Tom Lendacky authored
Provide support for Secure Encrypted Virtualization (SEV). This initial support defines a flag that is used by the kernel to determine if it is running with SEV active. Signed-off-by:
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Brijesh Singh authored
Update the AMD memory encryption document describing the Secure Encrypted Virtualization (SEV) feature. Signed-off-by:
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Zhou Chengming authored
We use alternatives_text_reserved() to check if the address is in the fixed pieces of alternative reserved, but the problem is that we don't hold the smp_alt mutex when call this function. So the list traversal may encounter a deleted list_head if another path is doing alternatives_smp_module_del(). One solution is that we can hold smp_alt mutex before call this function, but the difficult point is that the callers of this functions, arch_prepare_kprobe() and arch_prepare_optimized_kprobe(), are called inside the text_mutex. So we must hold smp_alt mutex before we go into these arch dependent code. But we can't now, the smp_alt mutex is the arch dependent part, only x86 has it. Maybe we can export another arch dependent callback to solve this. But there is a simpler way to handle this problem. We can reuse the text_mutex to protect smp_alt_modules instead of using another mutex. And all the arch dependent checks of kprobes are inside the text_mutex, so it's safe now. Signed-off-by:
Zhou Chengming <zhouchengming1@huawei.com> Reviewed-by:
Masami Hiramatsu <mhiramat@kernel.org> Acked-by:
Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: bp@suse.de Fixes: 2cfa1978 "ftrace/alternatives: Introducing *_text_reserved functions" Link: http://lkml.kernel.org/r/1509585501-79466-1-git-send-email-zhouchengming1@huawei.comSigned-off-by:
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Changbin Du authored
Some of the files generated by the build process were not listed. Signed-off-by:
Changbin Du <changbin.du@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: yamada.masahiro@socionext.com Link: http://lkml.kernel.org/r/1509939179-7556-5-git-send-email-changbin.du@intel.comSigned-off-by:
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Changbin Du authored
It avoids the following warning triggered by newer versions of mkisofs: -input-charset not specified, using utf-8 (detected in locale settings) Signed-off-by: -
Changbin Du authored
Recently I failed to build isoimage target, because the path of isolinux.bin changed to /usr/xxx/ISOLINUX/isolinux.bin, as well as ldlinux.c32 which changed to /usr/xxx/syslinux/modules/bios/ldlinux.c32. This patch improves the file search logic: - Show a error message instead of silent fail. - Add above new paths. Signed-off-by:
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Changbin Du authored
The build messages for fdimage/isoimage generation are pretty unstructured, just the raw shell command blocks are printed. Emit shortened messages similar to existing kbuild messages, and move the Makefile commands into a separate shell script - which is much easier to handle. This patch factors out the commands used for fdimage/isoimage generation from arch/x86/boot/Makefile to a new script arch/x86/boot/genimage.sh. Then it adds the new kbuild command 'genimage' which invokes the new script. All fdimages/isoimage files are now generated by a call to 'genimage' with different parameters. Now 'make isoimage' becomes: ... Kernel: arch/x86/boot/bzImage is ready (#30) GENIMAGE arch/x86/boot/image.iso Size of boot image is 4 sectors -> No emulation 15.37% done, estimate finish Sun Nov 5 23:36:57 2017 30.68% done, estimate finish Sun Nov 5 23:36:57 2017 46.04% done, estimate finish Sun Nov 5 23:36:57 2017 61.35% done, estimate finish Sun Nov 5 23:36:57 2017 76.69% done, estimate finish Sun Nov 5 23:36:57 2017 92.00% done, estimate finish Sun Nov 5 23:36:57 2017 Total translation table size: 2048 Total rockridge attributes bytes: 659 Total directory bytes: 0 Path table size(bytes): 10 Max brk space used 0 32608 extents written (63 MB) Kernel: arch/x86/boot/image.iso is ready Before: Kernel: arch/x86/boot/bzImage is ready (#63) rm -rf arch/x86/boot/isoimage mkdir arch/x86/boot/isoimage for i in lib lib64 share end ; do \ if [ -f /usr/$i/syslinux/isolinux.bin ] ; then \ cp /usr/$i/syslinux/isolinux.bin arch/x86/boot/isoimage ; \ if [ -f /usr/$i/syslinux/ldlinux.c32 ]; then \ cp /usr/$i/syslinux/ldlinux.c32 arch/x86/boot/isoimage ; \ fi ; \ break ; \ fi ; \ if [ $i = end ] ; then exit 1 ; fi ; \ done ... Suggested-by:
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Andy Lutomirski authored
We weren't testing the .limit and .limit_in_pages fields very well. Add more tests. This addition seems to trigger the "bits 16:19 are undefined" issue that was fixed in an earlier patch. I think that, at least on my CPU, the high nibble of the limit ends in LAR bits 16:19. Signed-off-by:
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Andy Lutomirski authored
Now that the main test infrastructure supports the GDT, run tests that will pass the kernel's GDT permission tests against the GDT. Signed-off-by:
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Andy Lutomirski authored
Much of the test design could apply to set_thread_area() (i.e. GDT), not just modify_ldt(). Add set_thread_area() to the install_valid_mode() helper. Signed-off-by:
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Andy Lutomirski authored
Bits 19:16 of LAR's result are undefined, and some upcoming improvements to the test case seem to trigger this. Mask off those bits to avoid spurious failures. commit 5b781c7e ("x86/tls: Forcibly set the accessed bit in TLS segments") adds a valid case in which LAR's output doesn't quite agree with set_thread_area()'s input. This isn't triggered in the test as is, but it will be if we start calling set_thread_area() with the accessed bit clear. Work around this discrepency. I've added a Fixes tag so that -stable can pick this up if neccesary. Signed-off-by:
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