19 files changed, 340 insertions, 133 deletions

diff --git a/arch/x86/crypto/sha512_ssse3_glue.c b/arch/x86/crypto/sha512_ssse3_glue.c
index f30cd10293f0..8626b03e83b7 100644
--- a/arch/x86/crypto/sha512_ssse3_glue.c
+++ b/arch/x86/crypto/sha512_ssse3_glue.c
@@ -141,7 +141,7 @@ static int sha512_ssse3_final(struct shash_desc *desc, u8 *out)
 
         /* save number of bits */
         bits[1] = cpu_to_be64(sctx->count[0] << 3);
-        bits[0] = cpu_to_be64(sctx->count[1] << 3) | sctx->count[0] >> 61;
+        bits[0] = cpu_to_be64(sctx->count[1] << 3 | sctx->count[0] >> 61);
 
         /* Pad out to 112 mod 128 and append length */
         index = sctx->count[0] & 0x7f;
diff --git a/arch/x86/include/asm/irq.h b/arch/x86/include/asm/irq.h
index cb6cfcd034cf..a80cbb88ea91 100644
--- a/arch/x86/include/asm/irq.h
+++ b/arch/x86/include/asm/irq.h
@@ -43,7 +43,7 @@ extern int vector_used_by_percpu_irq(unsigned int vector);
 extern void init_ISA_irqs(void);
 
 #ifdef CONFIG_X86_LOCAL_APIC
-void arch_trigger_all_cpu_backtrace(void);
+void arch_trigger_all_cpu_backtrace(bool);
 #define arch_trigger_all_cpu_backtrace arch_trigger_all_cpu_backtrace
 #endif
 
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 49314155b66c..49205d01b9ad 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -95,7 +95,7 @@ static inline gfn_t gfn_to_index(gfn_t gfn, gfn_t base_gfn, int level)
 #define KVM_REFILL_PAGES 25
 #define KVM_MAX_CPUID_ENTRIES 80
 #define KVM_NR_FIXED_MTRR_REGION 88
-#define KVM_NR_VAR_MTRR 8
+#define KVM_NR_VAR_MTRR 10
 
 #define ASYNC_PF_PER_VCPU 64
 
@@ -461,7 +461,7 @@ struct kvm_vcpu_arch {
         bool nmi_injected;    /* Trying to inject an NMI this entry */
 
         struct mtrr_state_type mtrr_state;
-        u32 pat;
+        u64 pat;
 
         unsigned switch_db_regs;
         unsigned long db[KVM_NR_DB_REGS];
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 14fd6fd75a19..6205f0c434db 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -231,6 +231,22 @@ static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
 
 #define ARCH_HAS_USER_SINGLE_STEP_INFO
 
+/*
+ * When hitting ptrace_stop(), we cannot return using SYSRET because
+ * that does not restore the full CPU state, only a minimal set.  The
+ * ptracer can change arbitrary register values, which is usually okay
+ * because the usual ptrace stops run off the signal delivery path which
+ * forces IRET; however, ptrace_event() stops happen in arbitrary places
+ * in the kernel and don't force IRET path.
+ *
+ * So force IRET path after a ptrace stop.
+ */
+#define arch_ptrace_stop_needed(code, info)                             \
+({                                                                      \
+        set_thread_flag(TIF_NOTIFY_RESUME);                             \
+        false;                                                          \
+})
+
 struct user_desc;
 extern int do_get_thread_area(struct task_struct *p, int idx,
                               struct user_desc __user *info);
diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index c3fcb5de5083..6a1e71bde323 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c
@@ -33,31 +33,41 @@ static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
 /* "in progress" flag of arch_trigger_all_cpu_backtrace */
 static unsigned long backtrace_flag;
 
-void arch_trigger_all_cpu_backtrace(void)
+void arch_trigger_all_cpu_backtrace(bool include_self)
 {
         int i;
+        int cpu = get_cpu();
 
-        if (test_and_set_bit(0, &backtrace_flag))
+        if (test_and_set_bit(0, &backtrace_flag)) {
                 /*
                  * If there is already a trigger_all_cpu_backtrace() in progress
                  * (backtrace_flag == 1), don't output double cpu dump infos.
                  */
+                put_cpu();
                 return;
+        }
 
         cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
+        if (!include_self)
+                cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
 
-        printk(KERN_INFO "sending NMI to all CPUs:\n");
-        apic->send_IPI_all(NMI_VECTOR);
+        if (!cpumask_empty(to_cpumask(backtrace_mask))) {
+                pr_info("sending NMI to %s CPUs:\n",
+                        (include_self ? "all" : "other"));
+                apic->send_IPI_mask(to_cpumask(backtrace_mask), NMI_VECTOR);
+        }
 
         /* Wait for up to 10 seconds for all CPUs to do the backtrace */
         for (i = 0; i < 10 * 1000; i++) {
                 if (cpumask_empty(to_cpumask(backtrace_mask)))
                         break;
                 mdelay(1);
+                touch_softlockup_watchdog();
         }
 
         clear_bit(0, &backtrace_flag);
         smp_mb__after_atomic();
+        put_cpu();
 }
 
 static int
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index f0da82b8e634..dbaa23e78b36 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -423,9 +423,10 @@ sysenter_past_esp:
         jnz sysenter_audit
 sysenter_do_call:
         cmpl $(NR_syscalls), %eax
-        jae syscall_badsys
+        jae sysenter_badsys
         call *sys_call_table(,%eax,4)
         movl %eax,PT_EAX(%esp)
+sysenter_after_call:
         LOCKDEP_SYS_EXIT
         DISABLE_INTERRUPTS(CLBR_ANY)
         TRACE_IRQS_OFF
@@ -675,7 +676,12 @@ END(syscall_fault)
 
 syscall_badsys:
         movl $-ENOSYS,PT_EAX(%esp)
-        jmp resume_userspace
+        jmp syscall_exit
+END(syscall_badsys)
+
+sysenter_badsys:
+        movl $-ENOSYS,PT_EAX(%esp)
+        jmp sysenter_after_call
 END(syscall_badsys)
         CFI_ENDPROC
 
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index a0da58db43a8..2851d63c1202 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -363,7 +363,7 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
 
                 /* Set up to return from userspace.  */
                 restorer = current->mm->context.vdso +
-                        selected_vdso32->sym___kernel_sigreturn;
+                        selected_vdso32->sym___kernel_rt_sigreturn;
                 if (ksig->ka.sa.sa_flags & SA_RESTORER)
                         restorer = ksig->ka.sa.sa_restorer;
                 put_user_ex(restorer, &frame->pretcode);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index ec8366c5cfea..b5e994ad0135 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1462,6 +1462,7 @@ static void svm_get_segment(struct kvm_vcpu *vcpu,
                  */
                 if (var->unusable)
                         var->db = 0;
+                var->dpl = to_svm(vcpu)->vmcb->save.cpl;
                 break;
         }
 }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f32a02578c0d..f6449334ec45 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1898,7 +1898,7 @@ static int set_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data)
                 if (!(data & HV_X64_MSR_TSC_REFERENCE_ENABLE))
                         break;
                 gfn = data >> HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT;
-                if (kvm_write_guest(kvm, data,
+                if (kvm_write_guest(kvm, gfn << HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT,
                         &tsc_ref, sizeof(tsc_ref)))
                         return 1;
                 mark_page_dirty(kvm, gfn);
diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index 3c0809a0631f..61b04fe36e66 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -11,7 +11,6 @@ VDSO32-$(CONFIG_COMPAT)		:= y
 
 # files to link into the vdso
 vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o vdso-fakesections.o
-vobjs-nox32 := vdso-fakesections.o
 
 # files to link into kernel
 obj-y                           += vma.o
@@ -67,7 +66,8 @@ $(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso2c FORCE
 #
 CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \
        $(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \
-       -fno-omit-frame-pointer -foptimize-sibling-calls
+       -fno-omit-frame-pointer -foptimize-sibling-calls \
+       -DDISABLE_BRANCH_PROFILING
 
 $(vobjs): KBUILD_CFLAGS += $(CFL)
 
@@ -134,7 +134,7 @@ override obj-dirs = $(dir $(obj)) $(obj)/vdso32/
 
 targets += vdso32/vdso32.lds
 targets += vdso32/note.o vdso32/vclock_gettime.o $(vdso32.so-y:%=vdso32/%.o)
-targets += vdso32/vclock_gettime.o
+targets += vdso32/vclock_gettime.o vdso32/vdso-fakesections.o
 
 $(obj)/vdso32.o: $(vdso32-images:%=$(obj)/%)
 
@@ -150,11 +150,13 @@ KBUILD_CFLAGS_32 += -m32 -msoft-float -mregparm=0 -fpic
 KBUILD_CFLAGS_32 += $(call cc-option, -fno-stack-protector)
 KBUILD_CFLAGS_32 += $(call cc-option, -foptimize-sibling-calls)
 KBUILD_CFLAGS_32 += -fno-omit-frame-pointer
+KBUILD_CFLAGS_32 += -DDISABLE_BRANCH_PROFILING
 $(vdso32-images:%=$(obj)/%.dbg): KBUILD_CFLAGS = $(KBUILD_CFLAGS_32)
 
 $(vdso32-images:%=$(obj)/%.dbg): $(obj)/vdso32-%.so.dbg: FORCE \
                                  $(obj)/vdso32/vdso32.lds \
                                  $(obj)/vdso32/vclock_gettime.o \
+                                 $(obj)/vdso32/vdso-fakesections.o \
                                  $(obj)/vdso32/note.o \
                                  $(obj)/vdso32/%.o
         $(call if_changed,vdso)
@@ -169,14 +171,24 @@ quiet_cmd_vdso = VDSO    $@
                  sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@'
 
 VDSO_LDFLAGS = -fPIC -shared $(call cc-ldoption, -Wl$(comma)--hash-style=sysv) \
-        -Wl,-Bsymbolic $(LTO_CFLAGS)
+        $(call cc-ldoption, -Wl$(comma)--build-id) -Wl,-Bsymbolic $(LTO_CFLAGS)
 GCOV_PROFILE := n
 
 #
-# Install the unstripped copies of vdso*.so.
+# Install the unstripped copies of vdso*.so.  If our toolchain supports
+# build-id, install .build-id links as well.
 #
 quiet_cmd_vdso_install = INSTALL $(@:install_%=%)
-      cmd_vdso_install = cp $< $(MODLIB)/vdso/$(@:install_%=%)
+define cmd_vdso_install
+        cp $< "$(MODLIB)/vdso/$(@:install_%=%)"; \
+        if readelf -n $< |grep -q 'Build ID'; then \
+          buildid=`readelf -n $< |grep 'Build ID' |sed -e 's/^.*Build ID: \(.*\)$$/\1/'`; \
+          first=`echo $$buildid | cut -b-2`; \
+          last=`echo $$buildid | cut -b3-`; \
+          mkdir -p "$(MODLIB)/vdso/.build-id/$$first"; \
+          ln -sf "../../$(@:install_%=%)" "$(MODLIB)/vdso/.build-id/$$first/$$last.debug"; \
+        fi
+endef
 
 vdso_img_insttargets := $(vdso_img_sodbg:%.dbg=install_%)
 
diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index b2e4f493e5b0..9793322751e0 100644
--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/vdso/vclock_gettime.c
@@ -11,9 +11,6 @@
  * Check with readelf after changing.
  */
 
-/* Disable profiling for userspace code: */
-#define DISABLE_BRANCH_PROFILING
-
 #include <uapi/linux/time.h>
 #include <asm/vgtod.h>
 #include <asm/hpet.h>
diff --git a/arch/x86/vdso/vdso-fakesections.c b/arch/x86/vdso/vdso-fakesections.c
index cb8a8d72c24b..aa5fbfab20a5 100644
--- a/arch/x86/vdso/vdso-fakesections.c
+++ b/arch/x86/vdso/vdso-fakesections.c
@@ -2,31 +2,20 @@
  * Copyright 2014 Andy Lutomirski
  * Subject to the GNU Public License, v.2
  *
- * Hack to keep broken Go programs working.
- *
- * The Go runtime had a couple of bugs: it would read the section table to try
- * to figure out how many dynamic symbols there were (it shouldn't have looked
- * at the section table at all) and, if there were no SHT_SYNDYM section table
- * entry, it would use an uninitialized value for the number of symbols.  As a
- * workaround, we supply a minimal section table.  vdso2c will adjust the
- * in-memory image so that "vdso_fake_sections" becomes the section table.
- *
- * The bug was introduced by:
- * https://code.google.com/p/go/source/detail?r=56ea40aac72b (2012-08-31)
- * and is being addressed in the Go runtime in this issue:
- * https://code.google.com/p/go/issues/detail?id=8197
+ * String table for loadable section headers.  See vdso2c.h for why
+ * this exists.
  */
 
-#ifndef __x86_64__
-#error This hack is specific to the 64-bit vDSO
-#endif
-
-#include <linux/elf.h>
-
-extern const __visible struct elf64_shdr vdso_fake_sections[];
-const __visible struct elf64_shdr vdso_fake_sections[] = {
-        {
-                .sh_type = SHT_DYNSYM,
-                .sh_entsize = sizeof(Elf64_Sym),
-        }
-};
+const char fake_shstrtab[] __attribute__((section(".fake_shstrtab"))) =
+        ".hash\0"
+        ".dynsym\0"
+        ".dynstr\0"
+        ".gnu.version\0"
+        ".gnu.version_d\0"
+        ".dynamic\0"
+        ".rodata\0"
+        ".fake_shstrtab\0"  /* Yay, self-referential code. */
+        ".note\0"
+        ".eh_frame_hdr\0"
+        ".eh_frame\0"
+        ".text";
diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S
index 2ec72f651ebf..9197544eea9a 100644
--- a/arch/x86/vdso/vdso-layout.lds.S
+++ b/arch/x86/vdso/vdso-layout.lds.S
@@ -6,6 +6,16 @@
  * This script controls its layout.
  */
 
+#if defined(BUILD_VDSO64)
+# define SHDR_SIZE 64
+#elif defined(BUILD_VDSO32) || defined(BUILD_VDSOX32)
+# define SHDR_SIZE 40
+#else
+# error unknown VDSO target
+#endif
+
+#define NUM_FAKE_SHDRS 13
+
 SECTIONS
 {
         . = SIZEOF_HEADERS;
@@ -18,36 +28,53 @@ SECTIONS
         .gnu.version_d  : { *(.gnu.version_d) }
         .gnu.version_r  : { *(.gnu.version_r) }
 
+        .dynamic        : { *(.dynamic) }               :text   :dynamic
+
+        .rodata         : {
+                *(.rodata*)
+                *(.data*)
+                *(.sdata*)
+                *(.got.plt) *(.got)
+                *(.gnu.linkonce.d.*)
+                *(.bss*)
+                *(.dynbss*)
+                *(.gnu.linkonce.b.*)
+
+                /*
+                 * Ideally this would live in a C file, but that won't
+                 * work cleanly for x32 until we start building the x32
+                 * C code using an x32 toolchain.
+                 */
+                VDSO_FAKE_SECTION_TABLE_START = .;
+                . = . + NUM_FAKE_SHDRS * SHDR_SIZE;
+                VDSO_FAKE_SECTION_TABLE_END = .;
+        }                                               :text
+
+        .fake_shstrtab  : { *(.fake_shstrtab) }         :text
+
+
         .note           : { *(.note.*) }                :text   :note
 
         .eh_frame_hdr   : { *(.eh_frame_hdr) }          :text   :eh_frame_hdr
         .eh_frame       : { KEEP (*(.eh_frame)) }       :text
 
-        .dynamic        : { *(.dynamic) }               :text   :dynamic
-
-        .rodata         : { *(.rodata*) }               :text
-        .data           : {
-              *(.data*)
-              *(.sdata*)
-              *(.got.plt) *(.got)
-              *(.gnu.linkonce.d.*)
-              *(.bss*)
-              *(.dynbss*)
-              *(.gnu.linkonce.b.*)
-        }
-
-        .altinstructions        : { *(.altinstructions) }
-        .altinstr_replacement   : { *(.altinstr_replacement) }
 
         /*
-         * Align the actual code well away from the non-instruction data.
-         * This is the best thing for the I-cache.
+         * Text is well-separated from actual data: there's plenty of
+         * stuff that isn't used at runtime in between.
          */
-        . = ALIGN(0x100);
 
         .text           : { *(.text*) }                 :text   =0x90909090,
 
         /*
+         * At the end so that eu-elflint stays happy when vdso2c strips
+         * these.  A better implementation would avoid allocating space
+         * for these.
+         */
+        .altinstructions        : { *(.altinstructions) }       :text
+        .altinstr_replacement   : { *(.altinstr_replacement) }  :text
+
+        /*
          * The remainder of the vDSO consists of special pages that are
          * shared between the kernel and userspace.  It needs to be at the
          * end so that it doesn't overlap the mapping of the actual
@@ -75,6 +102,7 @@ SECTIONS
         /DISCARD/ : {
                 *(.discard)
                 *(.discard.*)
+                *(__bug_table)
         }
 }
 
diff --git a/arch/x86/vdso/vdso.lds.S b/arch/x86/vdso/vdso.lds.S
index 75e3404c83b1..6807932643c2 100644
--- a/arch/x86/vdso/vdso.lds.S
+++ b/arch/x86/vdso/vdso.lds.S
@@ -6,6 +6,8 @@
  * the DSO.
  */
 
+#define BUILD_VDSO64
+
 #include "vdso-layout.lds.S"
 
 /*
diff --git a/arch/x86/vdso/vdso2c.c b/arch/x86/vdso/vdso2c.c
index 7a6bf50f9165..238dbe82776e 100644
--- a/arch/x86/vdso/vdso2c.c
+++ b/arch/x86/vdso/vdso2c.c
@@ -23,6 +23,8 @@ enum {
         sym_vvar_page,
         sym_hpet_page,
         sym_end_mapping,
+        sym_VDSO_FAKE_SECTION_TABLE_START,
+        sym_VDSO_FAKE_SECTION_TABLE_END,
 };
 
 const int special_pages[] = {
@@ -30,15 +32,26 @@ const int special_pages[] = {
         sym_hpet_page,
 };
 
-char const * const required_syms[] = {
-        [sym_vvar_page] = "vvar_page",
-        [sym_hpet_page] = "hpet_page",
-        [sym_end_mapping] = "end_mapping",
-        "VDSO32_NOTE_MASK",
-        "VDSO32_SYSENTER_RETURN",
-        "__kernel_vsyscall",
-        "__kernel_sigreturn",
-        "__kernel_rt_sigreturn",
+struct vdso_sym {
+        const char *name;
+        bool export;
+};
+
+struct vdso_sym required_syms[] = {
+        [sym_vvar_page] = {"vvar_page", true},
+        [sym_hpet_page] = {"hpet_page", true},
+        [sym_end_mapping] = {"end_mapping", true},
+        [sym_VDSO_FAKE_SECTION_TABLE_START] = {
+                "VDSO_FAKE_SECTION_TABLE_START", false
+        },
+        [sym_VDSO_FAKE_SECTION_TABLE_END] = {
+                "VDSO_FAKE_SECTION_TABLE_END", false
+        },
+        {"VDSO32_NOTE_MASK", true},
+        {"VDSO32_SYSENTER_RETURN", true},
+        {"__kernel_vsyscall", true},
+        {"__kernel_sigreturn", true},
+        {"__kernel_rt_sigreturn", true},
 };
 
 __attribute__((format(printf, 1, 2))) __attribute__((noreturn))
@@ -83,37 +96,21 @@ extern void bad_put_le(void);
 
 #define NSYMS (sizeof(required_syms) / sizeof(required_syms[0]))
 
-#define BITS 64
-#define GOFUNC go64
-#define Elf_Ehdr Elf64_Ehdr
-#define Elf_Shdr Elf64_Shdr
-#define Elf_Phdr Elf64_Phdr
-#define Elf_Sym Elf64_Sym
-#define Elf_Dyn Elf64_Dyn
+#define BITSFUNC3(name, bits) name##bits
+#define BITSFUNC2(name, bits) BITSFUNC3(name, bits)
+#define BITSFUNC(name) BITSFUNC2(name, ELF_BITS)
+
+#define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x
+#define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x)
+#define ELF(x) ELF_BITS_XFORM(ELF_BITS, x)
+
+#define ELF_BITS 64
 #include "vdso2c.h"
-#undef BITS
-#undef GOFUNC
-#undef Elf_Ehdr
-#undef Elf_Shdr
-#undef Elf_Phdr
-#undef Elf_Sym
-#undef Elf_Dyn
-
-#define BITS 32
-#define GOFUNC go32
-#define Elf_Ehdr Elf32_Ehdr
-#define Elf_Shdr Elf32_Shdr
-#define Elf_Phdr Elf32_Phdr
-#define Elf_Sym Elf32_Sym
-#define Elf_Dyn Elf32_Dyn
+#undef ELF_BITS
+
+#define ELF_BITS 32
 #include "vdso2c.h"
-#undef BITS
-#undef GOFUNC
-#undef Elf_Ehdr
-#undef Elf_Shdr
-#undef Elf_Phdr
-#undef Elf_Sym
-#undef Elf_Dyn
+#undef ELF_BITS
 
 static void go(void *addr, size_t len, FILE *outfile, const char *name)
 {
diff --git a/arch/x86/vdso/vdso2c.h b/arch/x86/vdso/vdso2c.h
index c6eefaf389b9..11b65d4f9414 100644
--- a/arch/x86/vdso/vdso2c.h
+++ b/arch/x86/vdso/vdso2c.h
@@ -4,23 +4,139 @@
  * are built for 32-bit userspace.
  */
 
-static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
+/*
+ * We're writing a section table for a few reasons:
+ *
+ * The Go runtime had a couple of bugs: it would read the section
+ * table to try to figure out how many dynamic symbols there were (it
+ * shouldn't have looked at the section table at all) and, if there
+ * were no SHT_SYNDYM section table entry, it would use an
+ * uninitialized value for the number of symbols.  An empty DYNSYM
+ * table would work, but I see no reason not to write a valid one (and
+ * keep full performance for old Go programs).  This hack is only
+ * needed on x86_64.
+ *
+ * The bug was introduced on 2012-08-31 by:
+ * https://code.google.com/p/go/source/detail?r=56ea40aac72b
+ * and was fixed on 2014-06-13 by:
+ * https://code.google.com/p/go/source/detail?r=fc1cd5e12595
+ *
+ * Binutils has issues debugging the vDSO: it reads the section table to
+ * find SHT_NOTE; it won't look at PT_NOTE for the in-memory vDSO, which
+ * would break build-id if we removed the section table.  Binutils
+ * also requires that shstrndx != 0.  See:
+ * https://sourceware.org/bugzilla/show_bug.cgi?id=17064
+ *
+ * elfutils might not look for PT_NOTE if there is a section table at
+ * all.  I don't know whether this matters for any practical purpose.
+ *
+ * For simplicity, rather than hacking up a partial section table, we
+ * just write a mostly complete one.  We omit non-dynamic symbols,
+ * though, since they're rather large.
+ *
+ * Once binutils gets fixed, we might be able to drop this for all but
+ * the 64-bit vdso, since build-id only works in kernel RPMs, and
+ * systems that update to new enough kernel RPMs will likely update
+ * binutils in sync.  build-id has never worked for home-built kernel
+ * RPMs without manual symlinking, and I suspect that no one ever does
+ * that.
+ */
+struct BITSFUNC(fake_sections)
+{
+        ELF(Shdr) *table;
+        unsigned long table_offset;
+        int count, max_count;
+
+        int in_shstrndx;
+        unsigned long shstr_offset;
+        const char *shstrtab;
+        size_t shstrtab_len;
+
+        int out_shstrndx;
+};
+
+static unsigned int BITSFUNC(find_shname)(struct BITSFUNC(fake_sections) *out,
+                                          const char *name)
+{
+        const char *outname = out->shstrtab;
+        while (outname - out->shstrtab < out->shstrtab_len) {
+                if (!strcmp(name, outname))
+                        return (outname - out->shstrtab) + out->shstr_offset;
+                outname += strlen(outname) + 1;
+        }
+
+        if (*name)
+                printf("Warning: could not find output name \"%s\"\n", name);
+        return out->shstr_offset + out->shstrtab_len - 1;  /* Use a null. */
+}
+
+static void BITSFUNC(init_sections)(struct BITSFUNC(fake_sections) *out)
+{
+        if (!out->in_shstrndx)
+                fail("didn't find the fake shstrndx\n");
+
+        memset(out->table, 0, out->max_count * sizeof(ELF(Shdr)));
+
+        if (out->max_count < 1)
+                fail("we need at least two fake output sections\n");
+
+        PUT_LE(&out->table[0].sh_type, SHT_NULL);
+        PUT_LE(&out->table[0].sh_name, BITSFUNC(find_shname)(out, ""));
+
+        out->count = 1;
+}
+
+static void BITSFUNC(copy_section)(struct BITSFUNC(fake_sections) *out,
+                                   int in_idx, const ELF(Shdr) *in,
+                                   const char *name)
+{
+        uint64_t flags = GET_LE(&in->sh_flags);
+
+        bool copy = flags & SHF_ALLOC &&
+                (GET_LE(&in->sh_size) ||
+                 (GET_LE(&in->sh_type) != SHT_RELA &&
+                  GET_LE(&in->sh_type) != SHT_REL)) &&
+                strcmp(name, ".altinstructions") &&
+                strcmp(name, ".altinstr_replacement");
+
+        if (!copy)
+                return;
+
+        if (out->count >= out->max_count)
+                fail("too many copied sections (max = %d)\n", out->max_count);
+
+        if (in_idx == out->in_shstrndx)
+                out->out_shstrndx = out->count;
+
+        out->table[out->count] = *in;
+        PUT_LE(&out->table[out->count].sh_name,
+               BITSFUNC(find_shname)(out, name));
+
+        /* elfutils requires that a strtab have the correct type. */
+        if (!strcmp(name, ".fake_shstrtab"))
+                PUT_LE(&out->table[out->count].sh_type, SHT_STRTAB);
+
+        out->count++;
+}
+
+static void BITSFUNC(go)(void *addr, size_t len,
+                         FILE *outfile, const char *name)
 {
         int found_load = 0;
         unsigned long load_size = -1;  /* Work around bogus warning */
         unsigned long data_size;
-        Elf_Ehdr *hdr = (Elf_Ehdr *)addr;
+        ELF(Ehdr) *hdr = (ELF(Ehdr) *)addr;
         int i;
         unsigned long j;
-        Elf_Shdr *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr,
+        ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr,
                 *alt_sec = NULL;
-        Elf_Dyn *dyn = 0, *dyn_end = 0;
+        ELF(Dyn) *dyn = 0, *dyn_end = 0;
         const char *secstrings;
         uint64_t syms[NSYMS] = {};
 
-        uint64_t fake_sections_value = 0, fake_sections_size = 0;
+        struct BITSFUNC(fake_sections) fake_sections = {};
 
-        Elf_Phdr *pt = (Elf_Phdr *)(addr + GET_LE(&hdr->e_phoff));
+        ELF(Phdr) *pt = (ELF(Phdr) *)(addr + GET_LE(&hdr->e_phoff));
 
         /* Walk the segment table. */
         for (i = 0; i < GET_LE(&hdr->e_phnum); i++) {
@@ -51,7 +167,7 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
         for (i = 0; dyn + i < dyn_end &&
                      GET_LE(&dyn[i].d_tag) != DT_NULL; i++) {
                 typeof(dyn[i].d_tag) tag = GET_LE(&dyn[i].d_tag);
-                if (tag == DT_REL || tag == DT_RELSZ ||
+                if (tag == DT_REL || tag == DT_RELSZ || tag == DT_RELA ||
                     tag == DT_RELENT || tag == DT_TEXTREL)
                         fail("vdso image contains dynamic relocations\n");
         }
@@ -61,7 +177,7 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
                 GET_LE(&hdr->e_shentsize)*GET_LE(&hdr->e_shstrndx);
         secstrings = addr + GET_LE(&secstrings_hdr->sh_offset);
         for (i = 0; i < GET_LE(&hdr->e_shnum); i++) {
-                Elf_Shdr *sh = addr + GET_LE(&hdr->e_shoff) +
+                ELF(Shdr) *sh = addr + GET_LE(&hdr->e_shoff) +
                         GET_LE(&hdr->e_shentsize) * i;
                 if (GET_LE(&sh->sh_type) == SHT_SYMTAB)
                         symtab_hdr = sh;
@@ -82,29 +198,63 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
              i < GET_LE(&symtab_hdr->sh_size) / GET_LE(&symtab_hdr->sh_entsize);
              i++) {
                 int k;
-                Elf_Sym *sym = addr + GET_LE(&symtab_hdr->sh_offset) +
+                ELF(Sym) *sym = addr + GET_LE(&symtab_hdr->sh_offset) +
                         GET_LE(&symtab_hdr->sh_entsize) * i;
                 const char *name = addr + GET_LE(&strtab_hdr->sh_offset) +
                         GET_LE(&sym->st_name);
 
                 for (k = 0; k < NSYMS; k++) {
-                        if (!strcmp(name, required_syms[k])) {
+                        if (!strcmp(name, required_syms[k].name)) {
                                 if (syms[k]) {
                                         fail("duplicate symbol %s\n",
-                                             required_syms[k]);
+                                             required_syms[k].name);
                                 }
                                 syms[k] = GET_LE(&sym->st_value);
                         }
                 }
 
-                if (!strcmp(name, "vdso_fake_sections")) {
-                        if (fake_sections_value)
-                                fail("duplicate vdso_fake_sections\n");
-                        fake_sections_value = GET_LE(&sym->st_value);
-                        fake_sections_size = GET_LE(&sym->st_size);
+                if (!strcmp(name, "fake_shstrtab")) {
+                        ELF(Shdr) *sh;
+
+                        fake_sections.in_shstrndx = GET_LE(&sym->st_shndx);
+                        fake_sections.shstrtab = addr + GET_LE(&sym->st_value);
+                        fake_sections.shstrtab_len = GET_LE(&sym->st_size);
+                        sh = addr + GET_LE(&hdr->e_shoff) +
+                                GET_LE(&hdr->e_shentsize) *
+                                fake_sections.in_shstrndx;
+                        fake_sections.shstr_offset = GET_LE(&sym->st_value) -
+                                GET_LE(&sh->sh_addr);
                 }
         }
 
+        /* Build the output section table. */
+        if (!syms[sym_VDSO_FAKE_SECTION_TABLE_START] ||
+            !syms[sym_VDSO_FAKE_SECTION_TABLE_END])
+                fail("couldn't find fake section table\n");
+        if ((syms[sym_VDSO_FAKE_SECTION_TABLE_END] -
+             syms[sym_VDSO_FAKE_SECTION_TABLE_START]) % sizeof(ELF(Shdr)))
+                fail("fake section table size isn't a multiple of sizeof(Shdr)\n");
+        fake_sections.table = addr + syms[sym_VDSO_FAKE_SECTION_TABLE_START];
+        fake_sections.table_offset = syms[sym_VDSO_FAKE_SECTION_TABLE_START];
+        fake_sections.max_count = (syms[sym_VDSO_FAKE_SECTION_TABLE_END] -
+                                   syms[sym_VDSO_FAKE_SECTION_TABLE_START]) /
+                sizeof(ELF(Shdr));
+
+        BITSFUNC(init_sections)(&fake_sections);
+        for (i = 0; i < GET_LE(&hdr->e_shnum); i++) {
+                ELF(Shdr) *sh = addr + GET_LE(&hdr->e_shoff) +
+                        GET_LE(&hdr->e_shentsize) * i;
+                BITSFUNC(copy_section)(&fake_sections, i, sh,
+                                       secstrings + GET_LE(&sh->sh_name));
+        }
+        if (!fake_sections.out_shstrndx)
+                fail("didn't generate shstrndx?!?\n");
+
+        PUT_LE(&hdr->e_shoff, fake_sections.table_offset);
+        PUT_LE(&hdr->e_shentsize, sizeof(ELF(Shdr)));
+        PUT_LE(&hdr->e_shnum, fake_sections.count);
+        PUT_LE(&hdr->e_shstrndx, fake_sections.out_shstrndx);
+
         /* Validate mapping addresses. */
         for (i = 0; i < sizeof(special_pages) / sizeof(special_pages[0]); i++) {
                 if (!syms[i])
@@ -112,25 +262,17 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
 
                 if (syms[i] % 4096)
                         fail("%s must be a multiple of 4096\n",
-                             required_syms[i]);
+                             required_syms[i].name);
                 if (syms[i] < data_size)
                         fail("%s must be after the text mapping\n",
-                             required_syms[i]);
+                             required_syms[i].name);
                 if (syms[sym_end_mapping] < syms[i] + 4096)
-                        fail("%s overruns end_mapping\n", required_syms[i]);
+                        fail("%s overruns end_mapping\n",
+                             required_syms[i].name);
         }
         if (syms[sym_end_mapping] % 4096)
                 fail("end_mapping must be a multiple of 4096\n");
 
-        /* Remove sections or use fakes */
-        if (fake_sections_size % sizeof(Elf_Shdr))
-                fail("vdso_fake_sections size is not a multiple of %ld\n",
-                     (long)sizeof(Elf_Shdr));
-        PUT_LE(&hdr->e_shoff, fake_sections_value);
-        PUT_LE(&hdr->e_shentsize, fake_sections_value ? sizeof(Elf_Shdr) : 0);
-        PUT_LE(&hdr->e_shnum, fake_sections_size / sizeof(Elf_Shdr));
-        PUT_LE(&hdr->e_shstrndx, SHN_UNDEF);
-
         if (!name) {
                 fwrite(addr, load_size, 1, outfile);
                 return;
@@ -168,9 +310,9 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name)
                         (unsigned long)GET_LE(&alt_sec->sh_size));
         }
         for (i = 0; i < NSYMS; i++) {
-                if (syms[i])
+                if (required_syms[i].export && syms[i])
                         fprintf(outfile, "\t.sym_%s = 0x%" PRIx64 ",\n",
-                                required_syms[i], syms[i]);
+                                required_syms[i].name, syms[i]);
         }
         fprintf(outfile, "};\n");
 }
diff --git a/arch/x86/vdso/vdso32/vdso-fakesections.c b/arch/x86/vdso/vdso32/vdso-fakesections.c
new file mode 100644
index 000000000000..541468e25265
--- /dev/null
+++ b/arch/x86/vdso/vdso32/vdso-fakesections.c
@@ -0,0 +1 @@
+#include "../vdso-fakesections.c"
diff --git a/arch/x86/vdso/vdsox32.lds.S b/arch/x86/vdso/vdsox32.lds.S
index 46b991b578a8..697c11ece90c 100644
--- a/arch/x86/vdso/vdsox32.lds.S
+++ b/arch/x86/vdso/vdsox32.lds.S
@@ -6,6 +6,8 @@
  * the DSO.
  */
 
+#define BUILD_VDSOX32
+
 #include "vdso-layout.lds.S"
 
 /*
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index e1513c47872a..5a5176de8d0a 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -62,6 +62,9 @@ struct linux_binprm;
    Only used for the 64-bit and x32 vdsos. */
 static unsigned long vdso_addr(unsigned long start, unsigned len)
 {
+#ifdef CONFIG_X86_32
+        return 0;
+#else
         unsigned long addr, end;
         unsigned offset;
         end = (start + PMD_SIZE - 1) & PMD_MASK;
@@ -83,6 +86,7 @@ static unsigned long vdso_addr(unsigned long start, unsigned len)
         addr = align_vdso_addr(addr);
 
         return addr;
+#endif
 }
 
 static int map_vdso(const struct vdso_image *image, bool calculate_addr)