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Merge branch 'spectre' of git://git.armlinux.org.uk/~rmk/linux-arm

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Pull ARM spectre updates from Russell King:
 "These are the currently known final bits that resolve the Spectre
  issues. big.Little systems used to be sufficiently identical in that
  there were no differences between individual CPUs in the system that
  mattered to the kernel. With the advent of the Spectre problem, the
  CPUs now have differences in how the workaround is applied.

  As a result of previous Spectre patches, these systems ended up
  reporting quite a lot of:

     "CPUx: Spectre v2: incorrect context switching function, system vulnerable"

  messages due to the action of the big.Little switcher causing the CPUs
  to be re-initialised regularly. This series resolves that issue by
  making the CPU vtable unique to each CPU.

  However, since this is used very early, before per-cpu is setup,
  per-cpu can't be used. We also have a problem that two of the methods
  are not called from preempt-safe paths, but thankfully these remain
  identical between all CPUs in the system. To make sure, we validate
  that these are identical during boot"

* 'spectre' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: spectre-v2: per-CPU vtables to work around big.Little systems
  ARM: add PROC_VTABLE and PROC_TABLE macros
  ARM: clean up per-processor check_bugs method call
  ARM: split out processor lookup
  ARM: make lookup_processor_type() non-__init
This commit is contained in:
Linus Torvalds
2018-11-18 10:45:09 -08:00
parent 1ce80e0fe9 383fb3ee80
commit cfaa9f029f
7 changed files with 115 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files

44
arch/arm/kernel/setup.c
View File

@@ -114,6 +114,11 @@ EXPORT_SYMBOL(elf_hwcap2);
#ifdef MULTI_CPU
struct processor processor __ro_after_init;
#if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
struct processor *cpu_vtable[NR_CPUS] = {
[0] = &processor,
};
#endif
#endif
#ifdef MULTI_TLB
struct cpu_tlb_fns cpu_tlb __ro_after_init;
@@ -666,28 +671,33 @@ static void __init smp_build_mpidr_hash(void)
}
#endif
/*
* locate processor in the list of supported processor types. The linker
* builds this table for us from the entries in arch/arm/mm/proc-*.S
*/
struct proc_info_list *lookup_processor(u32 midr)
{
struct proc_info_list *list = lookup_processor_type(midr);
if (!list) {
pr_err("CPU%u: configuration botched (ID %08x), CPU halted\n",
smp_processor_id(), midr);
while (1)
/* can't use cpu_relax() here as it may require MMU setup */;
}
return list;
}
static void __init setup_processor(void)
{
struct proc_info_list *list;
/*
* locate processor in the list of supported processor
* types. The linker builds this table for us from the
* entries in arch/arm/mm/proc-*.S
*/
list = lookup_processor_type(read_cpuid_id());
if (!list) {
pr_err("CPU configuration botched (ID %08x), unable to continue.\n",
read_cpuid_id());
while (1);
}
unsigned int midr = read_cpuid_id();
struct proc_info_list *list = lookup_processor(midr);
cpu_name = list->cpu_name;
__cpu_architecture = __get_cpu_architecture();
#ifdef MULTI_CPU
processor = *list->proc;
#endif
init_proc_vtable(list->proc);
#ifdef MULTI_TLB
cpu_tlb = *list->tlb;
#endif
@@ -699,7 +709,7 @@ static void __init setup_processor(void)
#endif
pr_info("CPU: %s [%08x] revision %d (ARMv%s), cr=%08lx\n",
cpu_name, read_cpuid_id(), read_cpuid_id() & 15,
list->cpu_name, midr, midr & 15,
proc_arch[cpu_architecture()], get_cr());
snprintf(init_utsname()->machine, __NEW_UTS_LEN + 1, "%s%c",