linux/arch/x86/kernel/signal_32.c
Linus Torvalds 877934769e - Cache the AMD debug registers in per-CPU variables to avoid MSR writes
where possible, when supporting a debug registers swap feature for
   SEV-ES guests
 
 - Add support for AMD's version of eIBRS called Automatic IBRS which is
   a set-and-forget control of indirect branch restriction speculation
   resources on privilege change
 
 - Add support for a new x86 instruction - LKGS - Load kernel GS which is
   part of the FRED infrastructure
 
 - Reset SPEC_CTRL upon init to accomodate use cases like kexec which
   rediscover
 
 - Other smaller fixes and cleanups
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Merge tag 'x86_cpu_for_v6.3_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 cpuid updates from Borislav Petkov:

 - Cache the AMD debug registers in per-CPU variables to avoid MSR
   writes where possible, when supporting a debug registers swap feature
   for SEV-ES guests

 - Add support for AMD's version of eIBRS called Automatic IBRS which is
   a set-and-forget control of indirect branch restriction speculation
   resources on privilege change

 - Add support for a new x86 instruction - LKGS - Load kernel GS which
   is part of the FRED infrastructure

 - Reset SPEC_CTRL upon init to accomodate use cases like kexec which
   rediscover

 - Other smaller fixes and cleanups

* tag 'x86_cpu_for_v6.3_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/amd: Cache debug register values in percpu variables
  KVM: x86: Propagate the AMD Automatic IBRS feature to the guest
  x86/cpu: Support AMD Automatic IBRS
  x86/cpu, kvm: Add the SMM_CTL MSR not present feature
  x86/cpu, kvm: Add the Null Selector Clears Base feature
  x86/cpu, kvm: Move X86_FEATURE_LFENCE_RDTSC to its native leaf
  x86/cpu, kvm: Add the NO_NESTED_DATA_BP feature
  KVM: x86: Move open-coded CPUID leaf 0x80000021 EAX bit propagation code
  x86/cpu, kvm: Add support for CPUID_80000021_EAX
  x86/gsseg: Add the new <asm/gsseg.h> header to <asm/asm-prototypes.h>
  x86/gsseg: Use the LKGS instruction if available for load_gs_index()
  x86/gsseg: Move load_gs_index() to its own new header file
  x86/gsseg: Make asm_load_gs_index() take an u16
  x86/opcode: Add the LKGS instruction to x86-opcode-map
  x86/cpufeature: Add the CPU feature bit for LKGS
  x86/bugs: Reset speculation control settings on init
  x86/cpu: Remove redundant extern x86_read_arch_cap_msr()
2023-02-21 14:51:40 -08:00

508 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
* 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
* 2000-12-* x86-64 compatibility mode signal handling by Andi Kleen
*/
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/personality.h>
#include <linux/compat.h>
#include <linux/binfmts.h>
#include <linux/syscalls.h>
#include <asm/ucontext.h>
#include <linux/uaccess.h>
#include <asm/fpu/signal.h>
#include <asm/ptrace.h>
#include <asm/user32.h>
#include <uapi/asm/sigcontext.h>
#include <asm/proto.h>
#include <asm/vdso.h>
#include <asm/sigframe.h>
#include <asm/sighandling.h>
#include <asm/smap.h>
#include <asm/gsseg.h>
#ifdef CONFIG_IA32_EMULATION
#include <asm/ia32_unistd.h>
static inline void reload_segments(struct sigcontext_32 *sc)
{
unsigned int cur;
savesegment(gs, cur);
if ((sc->gs | 0x03) != cur)
load_gs_index(sc->gs | 0x03);
savesegment(fs, cur);
if ((sc->fs | 0x03) != cur)
loadsegment(fs, sc->fs | 0x03);
savesegment(ds, cur);
if ((sc->ds | 0x03) != cur)
loadsegment(ds, sc->ds | 0x03);
savesegment(es, cur);
if ((sc->es | 0x03) != cur)
loadsegment(es, sc->es | 0x03);
}
#define sigset32_t compat_sigset_t
#define siginfo32_t compat_siginfo_t
#define restore_altstack32 compat_restore_altstack
#define unsafe_save_altstack32 unsafe_compat_save_altstack
#else
#define sigset32_t sigset_t
#define siginfo32_t siginfo_t
#define __NR_ia32_sigreturn __NR_sigreturn
#define __NR_ia32_rt_sigreturn __NR_rt_sigreturn
#define restore_altstack32 restore_altstack
#define unsafe_save_altstack32 unsafe_save_altstack
#define __copy_siginfo_to_user32 copy_siginfo_to_user
#endif
/*
* Do a signal return; undo the signal stack.
*/
static bool ia32_restore_sigcontext(struct pt_regs *regs,
struct sigcontext_32 __user *usc)
{
struct sigcontext_32 sc;
/* Always make any pending restarted system calls return -EINTR */
current->restart_block.fn = do_no_restart_syscall;
if (unlikely(copy_from_user(&sc, usc, sizeof(sc))))
return false;
/* Get only the ia32 registers. */
regs->bx = sc.bx;
regs->cx = sc.cx;
regs->dx = sc.dx;
regs->si = sc.si;
regs->di = sc.di;
regs->bp = sc.bp;
regs->ax = sc.ax;
regs->sp = sc.sp;
regs->ip = sc.ip;
/* Get CS/SS and force CPL3 */
regs->cs = sc.cs | 0x03;
regs->ss = sc.ss | 0x03;
regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
/* disable syscall checks */
regs->orig_ax = -1;
#ifdef CONFIG_IA32_EMULATION
/*
* Reload fs and gs if they have changed in the signal
* handler. This does not handle long fs/gs base changes in
* the handler, but does not clobber them at least in the
* normal case.
*/
reload_segments(&sc);
#else
loadsegment(gs, sc.gs);
regs->fs = sc.fs;
regs->es = sc.es;
regs->ds = sc.ds;
#endif
return fpu__restore_sig(compat_ptr(sc.fpstate), 1);
}
SYSCALL32_DEFINE0(sigreturn)
{
struct pt_regs *regs = current_pt_regs();
struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
sigset_t set;
if (!access_ok(frame, sizeof(*frame)))
goto badframe;
if (__get_user(set.sig[0], &frame->sc.oldmask)
|| __get_user(((__u32 *)&set)[1], &frame->extramask[0]))
goto badframe;
set_current_blocked(&set);
if (!ia32_restore_sigcontext(regs, &frame->sc))
goto badframe;
return regs->ax;
badframe:
signal_fault(regs, frame, "32bit sigreturn");
return 0;
}
SYSCALL32_DEFINE0(rt_sigreturn)
{
struct pt_regs *regs = current_pt_regs();
struct rt_sigframe_ia32 __user *frame;
sigset_t set;
frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
if (!access_ok(frame, sizeof(*frame)))
goto badframe;
if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
goto badframe;
set_current_blocked(&set);
if (!ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
goto badframe;
if (restore_altstack32(&frame->uc.uc_stack))
goto badframe;
return regs->ax;
badframe:
signal_fault(regs, frame, "32bit rt sigreturn");
return 0;
}
/*
* Set up a signal frame.
*/
#define get_user_seg(seg) ({ unsigned int v; savesegment(seg, v); v; })
static __always_inline int
__unsafe_setup_sigcontext32(struct sigcontext_32 __user *sc,
void __user *fpstate,
struct pt_regs *regs, unsigned int mask)
{
unsafe_put_user(get_user_seg(gs), (unsigned int __user *)&sc->gs, Efault);
#ifdef CONFIG_IA32_EMULATION
unsafe_put_user(get_user_seg(fs), (unsigned int __user *)&sc->fs, Efault);
unsafe_put_user(get_user_seg(ds), (unsigned int __user *)&sc->ds, Efault);
unsafe_put_user(get_user_seg(es), (unsigned int __user *)&sc->es, Efault);
#else
unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault);
unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault);
unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault);
#endif
unsafe_put_user(regs->di, &sc->di, Efault);
unsafe_put_user(regs->si, &sc->si, Efault);
unsafe_put_user(regs->bp, &sc->bp, Efault);
unsafe_put_user(regs->sp, &sc->sp, Efault);
unsafe_put_user(regs->bx, &sc->bx, Efault);
unsafe_put_user(regs->dx, &sc->dx, Efault);
unsafe_put_user(regs->cx, &sc->cx, Efault);
unsafe_put_user(regs->ax, &sc->ax, Efault);
unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
unsafe_put_user(current->thread.error_code, &sc->err, Efault);
unsafe_put_user(regs->ip, &sc->ip, Efault);
unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
unsafe_put_user(regs->flags, &sc->flags, Efault);
unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
unsafe_put_user(ptr_to_compat(fpstate), &sc->fpstate, Efault);
/* non-iBCS2 extensions.. */
unsafe_put_user(mask, &sc->oldmask, Efault);
unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
return 0;
Efault:
return -EFAULT;
}
#define unsafe_put_sigcontext32(sc, fp, regs, set, label) \
do { \
if (__unsafe_setup_sigcontext32(sc, fp, regs, set->sig[0])) \
goto label; \
} while(0)
int ia32_setup_frame(struct ksignal *ksig, struct pt_regs *regs)
{
sigset32_t *set = (sigset32_t *) sigmask_to_save();
struct sigframe_ia32 __user *frame;
void __user *restorer;
void __user *fp = NULL;
/* copy_to_user optimizes that into a single 8 byte store */
static const struct {
u16 poplmovl;
u32 val;
u16 int80;
} __attribute__((packed)) code = {
0xb858, /* popl %eax ; movl $...,%eax */
__NR_ia32_sigreturn,
0x80cd, /* int $0x80 */
};
frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
if (ksig->ka.sa.sa_flags & SA_RESTORER) {
restorer = ksig->ka.sa.sa_restorer;
} else {
/* Return stub is in 32bit vsyscall page */
if (current->mm->context.vdso)
restorer = current->mm->context.vdso +
vdso_image_32.sym___kernel_sigreturn;
else
restorer = &frame->retcode;
}
if (!user_access_begin(frame, sizeof(*frame)))
return -EFAULT;
unsafe_put_user(ksig->sig, &frame->sig, Efault);
unsafe_put_sigcontext32(&frame->sc, fp, regs, set, Efault);
unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
/*
* These are actually not used anymore, but left because some
* gdb versions depend on them as a marker.
*/
unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
user_access_end();
/* Set up registers for signal handler */
regs->sp = (unsigned long) frame;
regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
/* Make -mregparm=3 work */
regs->ax = ksig->sig;
regs->dx = 0;
regs->cx = 0;
#ifdef CONFIG_IA32_EMULATION
loadsegment(ds, __USER_DS);
loadsegment(es, __USER_DS);
#else
regs->ds = __USER_DS;
regs->es = __USER_DS;
#endif
regs->cs = __USER32_CS;
regs->ss = __USER_DS;
return 0;
Efault:
user_access_end();
return -EFAULT;
}
int ia32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
{
sigset32_t *set = (sigset32_t *) sigmask_to_save();
struct rt_sigframe_ia32 __user *frame;
void __user *restorer;
void __user *fp = NULL;
/* unsafe_put_user optimizes that into a single 8 byte store */
static const struct {
u8 movl;
u32 val;
u16 int80;
u8 pad;
} __attribute__((packed)) code = {
0xb8,
__NR_ia32_rt_sigreturn,
0x80cd,
0,
};
frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
if (!user_access_begin(frame, sizeof(*frame)))
return -EFAULT;
unsafe_put_user(ksig->sig, &frame->sig, Efault);
unsafe_put_user(ptr_to_compat(&frame->info), &frame->pinfo, Efault);
unsafe_put_user(ptr_to_compat(&frame->uc), &frame->puc, Efault);
/* Create the ucontext. */
if (static_cpu_has(X86_FEATURE_XSAVE))
unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
else
unsafe_put_user(0, &frame->uc.uc_flags, Efault);
unsafe_put_user(0, &frame->uc.uc_link, Efault);
unsafe_save_altstack32(&frame->uc.uc_stack, regs->sp, Efault);
if (ksig->ka.sa.sa_flags & SA_RESTORER)
restorer = ksig->ka.sa.sa_restorer;
else
restorer = current->mm->context.vdso +
vdso_image_32.sym___kernel_rt_sigreturn;
unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
/*
* Not actually used anymore, but left because some gdb
* versions need it.
*/
unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
unsafe_put_sigcontext32(&frame->uc.uc_mcontext, fp, regs, set, Efault);
unsafe_put_user(*(__u64 *)set, (__u64 __user *)&frame->uc.uc_sigmask, Efault);
user_access_end();
if (__copy_siginfo_to_user32(&frame->info, &ksig->info))
return -EFAULT;
/* Set up registers for signal handler */
regs->sp = (unsigned long) frame;
regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
/* Make -mregparm=3 work */
regs->ax = ksig->sig;
regs->dx = (unsigned long) &frame->info;
regs->cx = (unsigned long) &frame->uc;
#ifdef CONFIG_IA32_EMULATION
loadsegment(ds, __USER_DS);
loadsegment(es, __USER_DS);
#else
regs->ds = __USER_DS;
regs->es = __USER_DS;
#endif
regs->cs = __USER32_CS;
regs->ss = __USER_DS;
return 0;
Efault:
user_access_end();
return -EFAULT;
}
/*
* The siginfo_t structure and handing code is very easy
* to break in several ways. It must always be updated when new
* updates are made to the main siginfo_t, and
* copy_siginfo_to_user32() must be updated when the
* (arch-independent) copy_siginfo_to_user() is updated.
*
* It is also easy to put a new member in the siginfo_t
* which has implicit alignment which can move internal structure
* alignment around breaking the ABI. This can happen if you,
* for instance, put a plain 64-bit value in there.
*/
/*
* If adding a new si_code, there is probably new data in
* the siginfo. Make sure folks bumping the si_code
* limits also have to look at this code. Make sure any
* new fields are handled in copy_siginfo_to_user32()!
*/
static_assert(NSIGILL == 11);
static_assert(NSIGFPE == 15);
static_assert(NSIGSEGV == 9);
static_assert(NSIGBUS == 5);
static_assert(NSIGTRAP == 6);
static_assert(NSIGCHLD == 6);
static_assert(NSIGSYS == 2);
/* This is part of the ABI and can never change in size: */
static_assert(sizeof(siginfo32_t) == 128);
/* This is a part of the ABI and can never change in alignment */
static_assert(__alignof__(siginfo32_t) == 4);
/*
* The offsets of all the (unioned) si_fields are fixed
* in the ABI, of course. Make sure none of them ever
* move and are always at the beginning:
*/
static_assert(offsetof(siginfo32_t, _sifields) == 3 * sizeof(int));
static_assert(offsetof(siginfo32_t, si_signo) == 0);
static_assert(offsetof(siginfo32_t, si_errno) == 4);
static_assert(offsetof(siginfo32_t, si_code) == 8);
/*
* Ensure that the size of each si_field never changes.
* If it does, it is a sign that the
* copy_siginfo_to_user32() code below needs to updated
* along with the size in the CHECK_SI_SIZE().
*
* We repeat this check for both the generic and compat
* siginfos.
*
* Note: it is OK for these to grow as long as the whole
* structure stays within the padding size (checked
* above).
*/
#define CHECK_SI_OFFSET(name) \
static_assert(offsetof(siginfo32_t, _sifields) == \
offsetof(siginfo32_t, _sifields.name))
#define CHECK_SI_SIZE(name, size) \
static_assert(sizeof_field(siginfo32_t, _sifields.name) == size)
CHECK_SI_OFFSET(_kill);
CHECK_SI_SIZE (_kill, 2*sizeof(int));
static_assert(offsetof(siginfo32_t, si_pid) == 0xC);
static_assert(offsetof(siginfo32_t, si_uid) == 0x10);
CHECK_SI_OFFSET(_timer);
#ifdef CONFIG_COMPAT
/* compat_siginfo_t doesn't have si_sys_private */
CHECK_SI_SIZE (_timer, 3*sizeof(int));
#else
CHECK_SI_SIZE (_timer, 4*sizeof(int));
#endif
static_assert(offsetof(siginfo32_t, si_tid) == 0x0C);
static_assert(offsetof(siginfo32_t, si_overrun) == 0x10);
static_assert(offsetof(siginfo32_t, si_value) == 0x14);
CHECK_SI_OFFSET(_rt);
CHECK_SI_SIZE (_rt, 3*sizeof(int));
static_assert(offsetof(siginfo32_t, si_pid) == 0x0C);
static_assert(offsetof(siginfo32_t, si_uid) == 0x10);
static_assert(offsetof(siginfo32_t, si_value) == 0x14);
CHECK_SI_OFFSET(_sigchld);
CHECK_SI_SIZE (_sigchld, 5*sizeof(int));
static_assert(offsetof(siginfo32_t, si_pid) == 0x0C);
static_assert(offsetof(siginfo32_t, si_uid) == 0x10);
static_assert(offsetof(siginfo32_t, si_status) == 0x14);
static_assert(offsetof(siginfo32_t, si_utime) == 0x18);
static_assert(offsetof(siginfo32_t, si_stime) == 0x1C);
CHECK_SI_OFFSET(_sigfault);
CHECK_SI_SIZE (_sigfault, 4*sizeof(int));
static_assert(offsetof(siginfo32_t, si_addr) == 0x0C);
static_assert(offsetof(siginfo32_t, si_trapno) == 0x10);
static_assert(offsetof(siginfo32_t, si_addr_lsb) == 0x10);
static_assert(offsetof(siginfo32_t, si_lower) == 0x14);
static_assert(offsetof(siginfo32_t, si_upper) == 0x18);
static_assert(offsetof(siginfo32_t, si_pkey) == 0x14);
static_assert(offsetof(siginfo32_t, si_perf_data) == 0x10);
static_assert(offsetof(siginfo32_t, si_perf_type) == 0x14);
static_assert(offsetof(siginfo32_t, si_perf_flags) == 0x18);
CHECK_SI_OFFSET(_sigpoll);
CHECK_SI_SIZE (_sigpoll, 2*sizeof(int));
static_assert(offsetof(siginfo32_t, si_band) == 0x0C);
static_assert(offsetof(siginfo32_t, si_fd) == 0x10);
CHECK_SI_OFFSET(_sigsys);
CHECK_SI_SIZE (_sigsys, 3*sizeof(int));
static_assert(offsetof(siginfo32_t, si_call_addr) == 0x0C);
static_assert(offsetof(siginfo32_t, si_syscall) == 0x10);
static_assert(offsetof(siginfo32_t, si_arch) == 0x14);
/* any new si_fields should be added here */