summaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/process_64.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/kernel/process_64.c')
-rw-r--r--arch/x86/kernel/process_64.c863
1 files changed, 863 insertions, 0 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
new file mode 100644
index 000000000..7f94dbbc3
--- /dev/null
+++ b/arch/x86/kernel/process_64.c
@@ -0,0 +1,863 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 1995 Linus Torvalds
+ *
+ * Pentium III FXSR, SSE support
+ * Gareth Hughes <gareth@valinux.com>, May 2000
+ *
+ * X86-64 port
+ * Andi Kleen.
+ *
+ * CPU hotplug support - ashok.raj@intel.com
+ */
+
+/*
+ * This file handles the architecture-dependent parts of process handling..
+ */
+
+#include <linux/cpu.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/sched/task.h>
+#include <linux/sched/task_stack.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/elfcore.h>
+#include <linux/smp.h>
+#include <linux/slab.h>
+#include <linux/user.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+#include <linux/ptrace.h>
+#include <linux/notifier.h>
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/prctl.h>
+#include <linux/uaccess.h>
+#include <linux/io.h>
+#include <linux/ftrace.h>
+#include <linux/syscalls.h>
+
+#include <asm/processor.h>
+#include <asm/pkru.h>
+#include <asm/fpu/sched.h>
+#include <asm/mmu_context.h>
+#include <asm/prctl.h>
+#include <asm/desc.h>
+#include <asm/proto.h>
+#include <asm/ia32.h>
+#include <asm/debugreg.h>
+#include <asm/switch_to.h>
+#include <asm/xen/hypervisor.h>
+#include <asm/vdso.h>
+#include <asm/resctrl.h>
+#include <asm/unistd.h>
+#include <asm/fsgsbase.h>
+#ifdef CONFIG_IA32_EMULATION
+/* Not included via unistd.h */
+#include <asm/unistd_32_ia32.h>
+#endif
+
+#include "process.h"
+
+/* Prints also some state that isn't saved in the pt_regs */
+void __show_regs(struct pt_regs *regs, enum show_regs_mode mode,
+ const char *log_lvl)
+{
+ unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
+ unsigned long d0, d1, d2, d3, d6, d7;
+ unsigned int fsindex, gsindex;
+ unsigned int ds, es;
+
+ show_iret_regs(regs, log_lvl);
+
+ if (regs->orig_ax != -1)
+ pr_cont(" ORIG_RAX: %016lx\n", regs->orig_ax);
+ else
+ pr_cont("\n");
+
+ printk("%sRAX: %016lx RBX: %016lx RCX: %016lx\n",
+ log_lvl, regs->ax, regs->bx, regs->cx);
+ printk("%sRDX: %016lx RSI: %016lx RDI: %016lx\n",
+ log_lvl, regs->dx, regs->si, regs->di);
+ printk("%sRBP: %016lx R08: %016lx R09: %016lx\n",
+ log_lvl, regs->bp, regs->r8, regs->r9);
+ printk("%sR10: %016lx R11: %016lx R12: %016lx\n",
+ log_lvl, regs->r10, regs->r11, regs->r12);
+ printk("%sR13: %016lx R14: %016lx R15: %016lx\n",
+ log_lvl, regs->r13, regs->r14, regs->r15);
+
+ if (mode == SHOW_REGS_SHORT)
+ return;
+
+ if (mode == SHOW_REGS_USER) {
+ rdmsrl(MSR_FS_BASE, fs);
+ rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
+ printk("%sFS: %016lx GS: %016lx\n",
+ log_lvl, fs, shadowgs);
+ return;
+ }
+
+ asm("movl %%ds,%0" : "=r" (ds));
+ asm("movl %%es,%0" : "=r" (es));
+ asm("movl %%fs,%0" : "=r" (fsindex));
+ asm("movl %%gs,%0" : "=r" (gsindex));
+
+ rdmsrl(MSR_FS_BASE, fs);
+ rdmsrl(MSR_GS_BASE, gs);
+ rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
+
+ cr0 = read_cr0();
+ cr2 = read_cr2();
+ cr3 = __read_cr3();
+ cr4 = __read_cr4();
+
+ printk("%sFS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
+ log_lvl, fs, fsindex, gs, gsindex, shadowgs);
+ printk("%sCS: %04lx DS: %04x ES: %04x CR0: %016lx\n",
+ log_lvl, regs->cs, ds, es, cr0);
+ printk("%sCR2: %016lx CR3: %016lx CR4: %016lx\n",
+ log_lvl, cr2, cr3, cr4);
+
+ get_debugreg(d0, 0);
+ get_debugreg(d1, 1);
+ get_debugreg(d2, 2);
+ get_debugreg(d3, 3);
+ get_debugreg(d6, 6);
+ get_debugreg(d7, 7);
+
+ /* Only print out debug registers if they are in their non-default state. */
+ if (!((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) &&
+ (d6 == DR6_RESERVED) && (d7 == 0x400))) {
+ printk("%sDR0: %016lx DR1: %016lx DR2: %016lx\n",
+ log_lvl, d0, d1, d2);
+ printk("%sDR3: %016lx DR6: %016lx DR7: %016lx\n",
+ log_lvl, d3, d6, d7);
+ }
+
+ if (cpu_feature_enabled(X86_FEATURE_OSPKE))
+ printk("%sPKRU: %08x\n", log_lvl, read_pkru());
+}
+
+void release_thread(struct task_struct *dead_task)
+{
+ WARN_ON(dead_task->mm);
+}
+
+enum which_selector {
+ FS,
+ GS
+};
+
+/*
+ * Out of line to be protected from kprobes and tracing. If this would be
+ * traced or probed than any access to a per CPU variable happens with
+ * the wrong GS.
+ *
+ * It is not used on Xen paravirt. When paravirt support is needed, it
+ * needs to be renamed with native_ prefix.
+ */
+static noinstr unsigned long __rdgsbase_inactive(void)
+{
+ unsigned long gsbase;
+
+ lockdep_assert_irqs_disabled();
+
+ if (!static_cpu_has(X86_FEATURE_XENPV)) {
+ native_swapgs();
+ gsbase = rdgsbase();
+ native_swapgs();
+ } else {
+ instrumentation_begin();
+ rdmsrl(MSR_KERNEL_GS_BASE, gsbase);
+ instrumentation_end();
+ }
+
+ return gsbase;
+}
+
+/*
+ * Out of line to be protected from kprobes and tracing. If this would be
+ * traced or probed than any access to a per CPU variable happens with
+ * the wrong GS.
+ *
+ * It is not used on Xen paravirt. When paravirt support is needed, it
+ * needs to be renamed with native_ prefix.
+ */
+static noinstr void __wrgsbase_inactive(unsigned long gsbase)
+{
+ lockdep_assert_irqs_disabled();
+
+ if (!static_cpu_has(X86_FEATURE_XENPV)) {
+ native_swapgs();
+ wrgsbase(gsbase);
+ native_swapgs();
+ } else {
+ instrumentation_begin();
+ wrmsrl(MSR_KERNEL_GS_BASE, gsbase);
+ instrumentation_end();
+ }
+}
+
+/*
+ * Saves the FS or GS base for an outgoing thread if FSGSBASE extensions are
+ * not available. The goal is to be reasonably fast on non-FSGSBASE systems.
+ * It's forcibly inlined because it'll generate better code and this function
+ * is hot.
+ */
+static __always_inline void save_base_legacy(struct task_struct *prev_p,
+ unsigned short selector,
+ enum which_selector which)
+{
+ if (likely(selector == 0)) {
+ /*
+ * On Intel (without X86_BUG_NULL_SEG), the segment base could
+ * be the pre-existing saved base or it could be zero. On AMD
+ * (with X86_BUG_NULL_SEG), the segment base could be almost
+ * anything.
+ *
+ * This branch is very hot (it's hit twice on almost every
+ * context switch between 64-bit programs), and avoiding
+ * the RDMSR helps a lot, so we just assume that whatever
+ * value is already saved is correct. This matches historical
+ * Linux behavior, so it won't break existing applications.
+ *
+ * To avoid leaking state, on non-X86_BUG_NULL_SEG CPUs, if we
+ * report that the base is zero, it needs to actually be zero:
+ * see the corresponding logic in load_seg_legacy.
+ */
+ } else {
+ /*
+ * If the selector is 1, 2, or 3, then the base is zero on
+ * !X86_BUG_NULL_SEG CPUs and could be anything on
+ * X86_BUG_NULL_SEG CPUs. In the latter case, Linux
+ * has never attempted to preserve the base across context
+ * switches.
+ *
+ * If selector > 3, then it refers to a real segment, and
+ * saving the base isn't necessary.
+ */
+ if (which == FS)
+ prev_p->thread.fsbase = 0;
+ else
+ prev_p->thread.gsbase = 0;
+ }
+}
+
+static __always_inline void save_fsgs(struct task_struct *task)
+{
+ savesegment(fs, task->thread.fsindex);
+ savesegment(gs, task->thread.gsindex);
+ if (static_cpu_has(X86_FEATURE_FSGSBASE)) {
+ /*
+ * If FSGSBASE is enabled, we can't make any useful guesses
+ * about the base, and user code expects us to save the current
+ * value. Fortunately, reading the base directly is efficient.
+ */
+ task->thread.fsbase = rdfsbase();
+ task->thread.gsbase = __rdgsbase_inactive();
+ } else {
+ save_base_legacy(task, task->thread.fsindex, FS);
+ save_base_legacy(task, task->thread.gsindex, GS);
+ }
+}
+
+/*
+ * While a process is running,current->thread.fsbase and current->thread.gsbase
+ * may not match the corresponding CPU registers (see save_base_legacy()).
+ */
+void current_save_fsgs(void)
+{
+ unsigned long flags;
+
+ /* Interrupts need to be off for FSGSBASE */
+ local_irq_save(flags);
+ save_fsgs(current);
+ local_irq_restore(flags);
+}
+#if IS_ENABLED(CONFIG_KVM)
+EXPORT_SYMBOL_GPL(current_save_fsgs);
+#endif
+
+static __always_inline void loadseg(enum which_selector which,
+ unsigned short sel)
+{
+ if (which == FS)
+ loadsegment(fs, sel);
+ else
+ load_gs_index(sel);
+}
+
+static __always_inline void load_seg_legacy(unsigned short prev_index,
+ unsigned long prev_base,
+ unsigned short next_index,
+ unsigned long next_base,
+ enum which_selector which)
+{
+ if (likely(next_index <= 3)) {
+ /*
+ * The next task is using 64-bit TLS, is not using this
+ * segment at all, or is having fun with arcane CPU features.
+ */
+ if (next_base == 0) {
+ /*
+ * Nasty case: on AMD CPUs, we need to forcibly zero
+ * the base.
+ */
+ if (static_cpu_has_bug(X86_BUG_NULL_SEG)) {
+ loadseg(which, __USER_DS);
+ loadseg(which, next_index);
+ } else {
+ /*
+ * We could try to exhaustively detect cases
+ * under which we can skip the segment load,
+ * but there's really only one case that matters
+ * for performance: if both the previous and
+ * next states are fully zeroed, we can skip
+ * the load.
+ *
+ * (This assumes that prev_base == 0 has no
+ * false positives. This is the case on
+ * Intel-style CPUs.)
+ */
+ if (likely(prev_index | next_index | prev_base))
+ loadseg(which, next_index);
+ }
+ } else {
+ if (prev_index != next_index)
+ loadseg(which, next_index);
+ wrmsrl(which == FS ? MSR_FS_BASE : MSR_KERNEL_GS_BASE,
+ next_base);
+ }
+ } else {
+ /*
+ * The next task is using a real segment. Loading the selector
+ * is sufficient.
+ */
+ loadseg(which, next_index);
+ }
+}
+
+/*
+ * Store prev's PKRU value and load next's PKRU value if they differ. PKRU
+ * is not XSTATE managed on context switch because that would require a
+ * lookup in the task's FPU xsave buffer and require to keep that updated
+ * in various places.
+ */
+static __always_inline void x86_pkru_load(struct thread_struct *prev,
+ struct thread_struct *next)
+{
+ if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
+ return;
+
+ /* Stash the prev task's value: */
+ prev->pkru = rdpkru();
+
+ /*
+ * PKRU writes are slightly expensive. Avoid them when not
+ * strictly necessary:
+ */
+ if (prev->pkru != next->pkru)
+ wrpkru(next->pkru);
+}
+
+static __always_inline void x86_fsgsbase_load(struct thread_struct *prev,
+ struct thread_struct *next)
+{
+ if (static_cpu_has(X86_FEATURE_FSGSBASE)) {
+ /* Update the FS and GS selectors if they could have changed. */
+ if (unlikely(prev->fsindex || next->fsindex))
+ loadseg(FS, next->fsindex);
+ if (unlikely(prev->gsindex || next->gsindex))
+ loadseg(GS, next->gsindex);
+
+ /* Update the bases. */
+ wrfsbase(next->fsbase);
+ __wrgsbase_inactive(next->gsbase);
+ } else {
+ load_seg_legacy(prev->fsindex, prev->fsbase,
+ next->fsindex, next->fsbase, FS);
+ load_seg_legacy(prev->gsindex, prev->gsbase,
+ next->gsindex, next->gsbase, GS);
+ }
+}
+
+unsigned long x86_fsgsbase_read_task(struct task_struct *task,
+ unsigned short selector)
+{
+ unsigned short idx = selector >> 3;
+ unsigned long base;
+
+ if (likely((selector & SEGMENT_TI_MASK) == 0)) {
+ if (unlikely(idx >= GDT_ENTRIES))
+ return 0;
+
+ /*
+ * There are no user segments in the GDT with nonzero bases
+ * other than the TLS segments.
+ */
+ if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
+ return 0;
+
+ idx -= GDT_ENTRY_TLS_MIN;
+ base = get_desc_base(&task->thread.tls_array[idx]);
+ } else {
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+ struct ldt_struct *ldt;
+
+ /*
+ * If performance here mattered, we could protect the LDT
+ * with RCU. This is a slow path, though, so we can just
+ * take the mutex.
+ */
+ mutex_lock(&task->mm->context.lock);
+ ldt = task->mm->context.ldt;
+ if (unlikely(!ldt || idx >= ldt->nr_entries))
+ base = 0;
+ else
+ base = get_desc_base(ldt->entries + idx);
+ mutex_unlock(&task->mm->context.lock);
+#else
+ base = 0;
+#endif
+ }
+
+ return base;
+}
+
+unsigned long x86_gsbase_read_cpu_inactive(void)
+{
+ unsigned long gsbase;
+
+ if (boot_cpu_has(X86_FEATURE_FSGSBASE)) {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ gsbase = __rdgsbase_inactive();
+ local_irq_restore(flags);
+ } else {
+ rdmsrl(MSR_KERNEL_GS_BASE, gsbase);
+ }
+
+ return gsbase;
+}
+
+void x86_gsbase_write_cpu_inactive(unsigned long gsbase)
+{
+ if (boot_cpu_has(X86_FEATURE_FSGSBASE)) {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ __wrgsbase_inactive(gsbase);
+ local_irq_restore(flags);
+ } else {
+ wrmsrl(MSR_KERNEL_GS_BASE, gsbase);
+ }
+}
+
+unsigned long x86_fsbase_read_task(struct task_struct *task)
+{
+ unsigned long fsbase;
+
+ if (task == current)
+ fsbase = x86_fsbase_read_cpu();
+ else if (boot_cpu_has(X86_FEATURE_FSGSBASE) ||
+ (task->thread.fsindex == 0))
+ fsbase = task->thread.fsbase;
+ else
+ fsbase = x86_fsgsbase_read_task(task, task->thread.fsindex);
+
+ return fsbase;
+}
+
+unsigned long x86_gsbase_read_task(struct task_struct *task)
+{
+ unsigned long gsbase;
+
+ if (task == current)
+ gsbase = x86_gsbase_read_cpu_inactive();
+ else if (boot_cpu_has(X86_FEATURE_FSGSBASE) ||
+ (task->thread.gsindex == 0))
+ gsbase = task->thread.gsbase;
+ else
+ gsbase = x86_fsgsbase_read_task(task, task->thread.gsindex);
+
+ return gsbase;
+}
+
+void x86_fsbase_write_task(struct task_struct *task, unsigned long fsbase)
+{
+ WARN_ON_ONCE(task == current);
+
+ task->thread.fsbase = fsbase;
+}
+
+void x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase)
+{
+ WARN_ON_ONCE(task == current);
+
+ task->thread.gsbase = gsbase;
+}
+
+static void
+start_thread_common(struct pt_regs *regs, unsigned long new_ip,
+ unsigned long new_sp,
+ unsigned int _cs, unsigned int _ss, unsigned int _ds)
+{
+ WARN_ON_ONCE(regs != current_pt_regs());
+
+ if (static_cpu_has(X86_BUG_NULL_SEG)) {
+ /* Loading zero below won't clear the base. */
+ loadsegment(fs, __USER_DS);
+ load_gs_index(__USER_DS);
+ }
+
+ loadsegment(fs, 0);
+ loadsegment(es, _ds);
+ loadsegment(ds, _ds);
+ load_gs_index(0);
+
+ regs->ip = new_ip;
+ regs->sp = new_sp;
+ regs->cs = _cs;
+ regs->ss = _ss;
+ regs->flags = X86_EFLAGS_IF;
+}
+
+void
+start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
+{
+ start_thread_common(regs, new_ip, new_sp,
+ __USER_CS, __USER_DS, 0);
+}
+EXPORT_SYMBOL_GPL(start_thread);
+
+#ifdef CONFIG_COMPAT
+void compat_start_thread(struct pt_regs *regs, u32 new_ip, u32 new_sp, bool x32)
+{
+ start_thread_common(regs, new_ip, new_sp,
+ x32 ? __USER_CS : __USER32_CS,
+ __USER_DS, __USER_DS);
+}
+#endif
+
+/*
+ * switch_to(x,y) should switch tasks from x to y.
+ *
+ * This could still be optimized:
+ * - fold all the options into a flag word and test it with a single test.
+ * - could test fs/gs bitsliced
+ *
+ * Kprobes not supported here. Set the probe on schedule instead.
+ * Function graph tracer not supported too.
+ */
+__no_kmsan_checks
+__visible __notrace_funcgraph struct task_struct *
+__switch_to(struct task_struct *prev_p, struct task_struct *next_p)
+{
+ struct thread_struct *prev = &prev_p->thread;
+ struct thread_struct *next = &next_p->thread;
+ struct fpu *prev_fpu = &prev->fpu;
+ int cpu = smp_processor_id();
+
+ WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ENTRY) &&
+ this_cpu_read(hardirq_stack_inuse));
+
+ if (!test_thread_flag(TIF_NEED_FPU_LOAD))
+ switch_fpu_prepare(prev_fpu, cpu);
+
+ /* We must save %fs and %gs before load_TLS() because
+ * %fs and %gs may be cleared by load_TLS().
+ *
+ * (e.g. xen_load_tls())
+ */
+ save_fsgs(prev_p);
+
+ /*
+ * Load TLS before restoring any segments so that segment loads
+ * reference the correct GDT entries.
+ */
+ load_TLS(next, cpu);
+
+ /*
+ * Leave lazy mode, flushing any hypercalls made here. This
+ * must be done after loading TLS entries in the GDT but before
+ * loading segments that might reference them.
+ */
+ arch_end_context_switch(next_p);
+
+ /* Switch DS and ES.
+ *
+ * Reading them only returns the selectors, but writing them (if
+ * nonzero) loads the full descriptor from the GDT or LDT. The
+ * LDT for next is loaded in switch_mm, and the GDT is loaded
+ * above.
+ *
+ * We therefore need to write new values to the segment
+ * registers on every context switch unless both the new and old
+ * values are zero.
+ *
+ * Note that we don't need to do anything for CS and SS, as
+ * those are saved and restored as part of pt_regs.
+ */
+ savesegment(es, prev->es);
+ if (unlikely(next->es | prev->es))
+ loadsegment(es, next->es);
+
+ savesegment(ds, prev->ds);
+ if (unlikely(next->ds | prev->ds))
+ loadsegment(ds, next->ds);
+
+ x86_fsgsbase_load(prev, next);
+
+ x86_pkru_load(prev, next);
+
+ /*
+ * Switch the PDA and FPU contexts.
+ */
+ this_cpu_write(current_task, next_p);
+ this_cpu_write(cpu_current_top_of_stack, task_top_of_stack(next_p));
+
+ switch_fpu_finish();
+
+ /* Reload sp0. */
+ update_task_stack(next_p);
+
+ switch_to_extra(prev_p, next_p);
+
+ if (static_cpu_has_bug(X86_BUG_SYSRET_SS_ATTRS)) {
+ /*
+ * AMD CPUs have a misfeature: SYSRET sets the SS selector but
+ * does not update the cached descriptor. As a result, if we
+ * do SYSRET while SS is NULL, we'll end up in user mode with
+ * SS apparently equal to __USER_DS but actually unusable.
+ *
+ * The straightforward workaround would be to fix it up just
+ * before SYSRET, but that would slow down the system call
+ * fast paths. Instead, we ensure that SS is never NULL in
+ * system call context. We do this by replacing NULL SS
+ * selectors at every context switch. SYSCALL sets up a valid
+ * SS, so the only way to get NULL is to re-enter the kernel
+ * from CPL 3 through an interrupt. Since that can't happen
+ * in the same task as a running syscall, we are guaranteed to
+ * context switch between every interrupt vector entry and a
+ * subsequent SYSRET.
+ *
+ * We read SS first because SS reads are much faster than
+ * writes. Out of caution, we force SS to __KERNEL_DS even if
+ * it previously had a different non-NULL value.
+ */
+ unsigned short ss_sel;
+ savesegment(ss, ss_sel);
+ if (ss_sel != __KERNEL_DS)
+ loadsegment(ss, __KERNEL_DS);
+ }
+
+ /* Load the Intel cache allocation PQR MSR. */
+ resctrl_sched_in(next_p);
+
+ return prev_p;
+}
+
+void set_personality_64bit(void)
+{
+ /* inherit personality from parent */
+
+ /* Make sure to be in 64bit mode */
+ clear_thread_flag(TIF_ADDR32);
+ /* Pretend that this comes from a 64bit execve */
+ task_pt_regs(current)->orig_ax = __NR_execve;
+ current_thread_info()->status &= ~TS_COMPAT;
+ if (current->mm)
+ current->mm->context.flags = MM_CONTEXT_HAS_VSYSCALL;
+
+ /* TBD: overwrites user setup. Should have two bits.
+ But 64bit processes have always behaved this way,
+ so it's not too bad. The main problem is just that
+ 32bit children are affected again. */
+ current->personality &= ~READ_IMPLIES_EXEC;
+}
+
+static void __set_personality_x32(void)
+{
+#ifdef CONFIG_X86_X32_ABI
+ if (current->mm)
+ current->mm->context.flags = 0;
+
+ current->personality &= ~READ_IMPLIES_EXEC;
+ /*
+ * in_32bit_syscall() uses the presence of the x32 syscall bit
+ * flag to determine compat status. The x86 mmap() code relies on
+ * the syscall bitness so set x32 syscall bit right here to make
+ * in_32bit_syscall() work during exec().
+ *
+ * Pretend to come from a x32 execve.
+ */
+ task_pt_regs(current)->orig_ax = __NR_x32_execve | __X32_SYSCALL_BIT;
+ current_thread_info()->status &= ~TS_COMPAT;
+#endif
+}
+
+static void __set_personality_ia32(void)
+{
+#ifdef CONFIG_IA32_EMULATION
+ if (current->mm) {
+ /*
+ * uprobes applied to this MM need to know this and
+ * cannot use user_64bit_mode() at that time.
+ */
+ current->mm->context.flags = MM_CONTEXT_UPROBE_IA32;
+ }
+
+ current->personality |= force_personality32;
+ /* Prepare the first "return" to user space */
+ task_pt_regs(current)->orig_ax = __NR_ia32_execve;
+ current_thread_info()->status |= TS_COMPAT;
+#endif
+}
+
+void set_personality_ia32(bool x32)
+{
+ /* Make sure to be in 32bit mode */
+ set_thread_flag(TIF_ADDR32);
+
+ if (x32)
+ __set_personality_x32();
+ else
+ __set_personality_ia32();
+}
+EXPORT_SYMBOL_GPL(set_personality_ia32);
+
+#ifdef CONFIG_CHECKPOINT_RESTORE
+static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr)
+{
+ int ret;
+
+ ret = map_vdso_once(image, addr);
+ if (ret)
+ return ret;
+
+ return (long)image->size;
+}
+#endif
+
+long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2)
+{
+ int ret = 0;
+
+ switch (option) {
+ case ARCH_SET_GS: {
+ if (unlikely(arg2 >= TASK_SIZE_MAX))
+ return -EPERM;
+
+ preempt_disable();
+ /*
+ * ARCH_SET_GS has always overwritten the index
+ * and the base. Zero is the most sensible value
+ * to put in the index, and is the only value that
+ * makes any sense if FSGSBASE is unavailable.
+ */
+ if (task == current) {
+ loadseg(GS, 0);
+ x86_gsbase_write_cpu_inactive(arg2);
+
+ /*
+ * On non-FSGSBASE systems, save_base_legacy() expects
+ * that we also fill in thread.gsbase.
+ */
+ task->thread.gsbase = arg2;
+
+ } else {
+ task->thread.gsindex = 0;
+ x86_gsbase_write_task(task, arg2);
+ }
+ preempt_enable();
+ break;
+ }
+ case ARCH_SET_FS: {
+ /*
+ * Not strictly needed for %fs, but do it for symmetry
+ * with %gs
+ */
+ if (unlikely(arg2 >= TASK_SIZE_MAX))
+ return -EPERM;
+
+ preempt_disable();
+ /*
+ * Set the selector to 0 for the same reason
+ * as %gs above.
+ */
+ if (task == current) {
+ loadseg(FS, 0);
+ x86_fsbase_write_cpu(arg2);
+
+ /*
+ * On non-FSGSBASE systems, save_base_legacy() expects
+ * that we also fill in thread.fsbase.
+ */
+ task->thread.fsbase = arg2;
+ } else {
+ task->thread.fsindex = 0;
+ x86_fsbase_write_task(task, arg2);
+ }
+ preempt_enable();
+ break;
+ }
+ case ARCH_GET_FS: {
+ unsigned long base = x86_fsbase_read_task(task);
+
+ ret = put_user(base, (unsigned long __user *)arg2);
+ break;
+ }
+ case ARCH_GET_GS: {
+ unsigned long base = x86_gsbase_read_task(task);
+
+ ret = put_user(base, (unsigned long __user *)arg2);
+ break;
+ }
+
+#ifdef CONFIG_CHECKPOINT_RESTORE
+# ifdef CONFIG_X86_X32_ABI
+ case ARCH_MAP_VDSO_X32:
+ return prctl_map_vdso(&vdso_image_x32, arg2);
+# endif
+# if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
+ case ARCH_MAP_VDSO_32:
+ return prctl_map_vdso(&vdso_image_32, arg2);
+# endif
+ case ARCH_MAP_VDSO_64:
+ return prctl_map_vdso(&vdso_image_64, arg2);
+#endif
+
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ return ret;
+}
+
+SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
+{
+ long ret;
+
+ ret = do_arch_prctl_64(current, option, arg2);
+ if (ret == -EINVAL)
+ ret = do_arch_prctl_common(option, arg2);
+
+ return ret;
+}
+
+#ifdef CONFIG_IA32_EMULATION
+COMPAT_SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
+{
+ return do_arch_prctl_common(option, arg2);
+}
+#endif
+
+unsigned long KSTK_ESP(struct task_struct *task)
+{
+ return task_pt_regs(task)->sp;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-04 15:30:43 +0000