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authorLinus Torvalds <torvalds@linux-foundation.org>2020-01-28 11:08:13 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-01-28 11:08:13 -0800
commitbcc8aff6af53907ecb60e5aa8b34fbd429408a7a (patch)
tree231702d19f95958814e0a7375b9ef7dfd10a9c97
parent435dd727a411004d9402ad0c868c958408271a48 (diff)
parent183ef7adf4ed638ac0fb0c3c9a71fc00e8512b61 (diff)
Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm updates from Ingo Molnar: "Misc updates: - Remove last remaining calls to exception_enter/exception_exit() and simplify the entry code some more. - Remove force_iret() - Add support for "Fast Short Rep Mov", which is available starting with Ice Lake Intel CPUs - and make the x86 assembly version of memmove() use REP MOV for all sizes when FSRM is available. - Micro-optimize/simplify the 32-bit boot code a bit. - Use a more future-proof SYSRET instruction mnemonic" * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/boot: Simplify calculation of output address x86/entry/64: Add instruction suffix to SYSRET x86: Remove force_iret() x86/cpufeatures: Add support for fast short REP; MOVSB x86/context-tracking: Remove exception_enter/exit() from KVM_PV_REASON_PAGE_NOT_PRESENT async page fault x86/context-tracking: Remove exception_enter/exit() from do_page_fault()
-rw-r--r--arch/x86/boot/compressed/head_32.S8
-rw-r--r--arch/x86/entry/entry_64.S2
-rw-r--r--arch/x86/ia32/ia32_signal.c2
-rw-r--r--arch/x86/include/asm/cpufeatures.h1
-rw-r--r--arch/x86/include/asm/ptrace.h16
-rw-r--r--arch/x86/include/asm/thread_info.h9
-rw-r--r--arch/x86/kernel/kvm.c4
-rw-r--r--arch/x86/kernel/process_32.c1
-rw-r--r--arch/x86/kernel/process_64.c1
-rw-r--r--arch/x86/kernel/signal.c2
-rw-r--r--arch/x86/kernel/vm86_32.c1
-rw-r--r--arch/x86/lib/memmove_64.S7
-rw-r--r--arch/x86/mm/fault.c39
13 files changed, 21 insertions, 72 deletions
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index e43ac17cb9fb..73f17d0544dd 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -189,11 +189,9 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
/* push arguments for extract_kernel: */
pushl $z_output_len /* decompressed length, end of relocs */
- movl BP_init_size(%esi), %eax
- subl $_end, %eax
- movl %ebx, %ebp
- subl %eax, %ebp
- pushl %ebp /* output address */
+ leal _end(%ebx), %eax
+ subl BP_init_size(%esi), %eax
+ pushl %eax /* output address */
pushl $z_input_len /* input_len */
leal input_data(%ebx), %eax
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 76942cbd95a1..f2bb91e87877 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1728,7 +1728,7 @@ SYM_CODE_END(nmi)
SYM_CODE_START(ignore_sysret)
UNWIND_HINT_EMPTY
mov $-ENOSYS, %eax
- sysret
+ sysretl
SYM_CODE_END(ignore_sysret)
#endif
diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 30416d7f19d4..a3aefe9b9401 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -114,8 +114,6 @@ static int ia32_restore_sigcontext(struct pt_regs *regs,
err |= fpu__restore_sig(buf, 1);
- force_iret();
-
return err;
}
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index e9b62498fe75..98c60fa31ced 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -357,6 +357,7 @@
/* Intel-defined CPU features, CPUID level 0x00000007:0 (EDX), word 18 */
#define X86_FEATURE_AVX512_4VNNIW (18*32+ 2) /* AVX-512 Neural Network Instructions */
#define X86_FEATURE_AVX512_4FMAPS (18*32+ 3) /* AVX-512 Multiply Accumulation Single precision */
+#define X86_FEATURE_FSRM (18*32+ 4) /* Fast Short Rep Mov */
#define X86_FEATURE_AVX512_VP2INTERSECT (18*32+ 8) /* AVX-512 Intersect for D/Q */
#define X86_FEATURE_MD_CLEAR (18*32+10) /* VERW clears CPU buffers */
#define X86_FEATURE_TSX_FORCE_ABORT (18*32+13) /* "" TSX_FORCE_ABORT */
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 5057a8ed100b..78897a8da01f 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -339,22 +339,6 @@ static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
#define ARCH_HAS_USER_SINGLE_STEP_REPORT
-/*
- * 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) \
-({ \
- force_iret(); \
- 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/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index d779366ce3f8..cf4327986e98 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -239,15 +239,6 @@ static inline int arch_within_stack_frames(const void * const stack,
current_thread_info()->status & TS_COMPAT)
#endif
-/*
- * Force syscall return via IRET by making it look as if there was
- * some work pending. IRET is our most capable (but slowest) syscall
- * return path, which is able to restore modified SS, CS and certain
- * EFLAGS values that other (fast) syscall return instructions
- * are not able to restore properly.
- */
-#define force_iret() set_thread_flag(TIF_NOTIFY_RESUME)
-
extern void arch_task_cache_init(void);
extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
extern void arch_release_task_struct(struct task_struct *tsk);
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 32ef1ee733b7..81045aabb6f4 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -245,17 +245,13 @@ NOKPROBE_SYMBOL(kvm_read_and_reset_pf_reason);
dotraplinkage void
do_async_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address)
{
- enum ctx_state prev_state;
-
switch (kvm_read_and_reset_pf_reason()) {
default:
do_page_fault(regs, error_code, address);
break;
case KVM_PV_REASON_PAGE_NOT_PRESENT:
/* page is swapped out by the host. */
- prev_state = exception_enter();
kvm_async_pf_task_wait((u32)address, !user_mode(regs));
- exception_exit(prev_state);
break;
case KVM_PV_REASON_PAGE_READY:
rcu_irq_enter();
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 323499f48858..5052ced43373 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -124,7 +124,6 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
regs->ip = new_ip;
regs->sp = new_sp;
regs->flags = X86_EFLAGS_IF;
- force_iret();
}
EXPORT_SYMBOL_GPL(start_thread);
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 506d66830d4d..ffd497804dbc 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -394,7 +394,6 @@ start_thread_common(struct pt_regs *regs, unsigned long new_ip,
regs->cs = _cs;
regs->ss = _ss;
regs->flags = X86_EFLAGS_IF;
- force_iret();
}
void
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 8eb7193e158d..8a29573851a3 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -151,8 +151,6 @@ static int restore_sigcontext(struct pt_regs *regs,
err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32));
- force_iret();
-
return err;
}
diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index a76c12b38e92..91d55454e702 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -381,7 +381,6 @@ static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus)
mark_screen_rdonly(tsk->mm);
memcpy((struct kernel_vm86_regs *)regs, &vm86regs, sizeof(vm86regs));
- force_iret();
return regs->ax;
}
diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S
index 337830d7a59c..7ff00ea64e4f 100644
--- a/arch/x86/lib/memmove_64.S
+++ b/arch/x86/lib/memmove_64.S
@@ -29,10 +29,7 @@
SYM_FUNC_START_ALIAS(memmove)
SYM_FUNC_START(__memmove)
- /* Handle more 32 bytes in loop */
mov %rdi, %rax
- cmp $0x20, %rdx
- jb 1f
/* Decide forward/backward copy mode */
cmp %rdi, %rsi
@@ -42,7 +39,9 @@ SYM_FUNC_START(__memmove)
cmp %rdi, %r8
jg 2f
+ /* FSRM implies ERMS => no length checks, do the copy directly */
.Lmemmove_begin_forward:
+ ALTERNATIVE "cmp $0x20, %rdx; jb 1f", "", X86_FEATURE_FSRM
ALTERNATIVE "", "movq %rdx, %rcx; rep movsb; retq", X86_FEATURE_ERMS
/*
@@ -114,6 +113,8 @@ SYM_FUNC_START(__memmove)
*/
.p2align 4
2:
+ cmp $0x20, %rdx
+ jb 1f
cmp $680, %rdx
jb 6f
cmp %dil, %sil
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index c9c8523a3a48..fa4ea09593ab 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1487,27 +1487,6 @@ good_area:
}
NOKPROBE_SYMBOL(do_user_addr_fault);
-/*
- * Explicitly marked noinline such that the function tracer sees this as the
- * page_fault entry point.
- */
-static noinline void
-__do_page_fault(struct pt_regs *regs, unsigned long hw_error_code,
- unsigned long address)
-{
- prefetchw(&current->mm->mmap_sem);
-
- if (unlikely(kmmio_fault(regs, address)))
- return;
-
- /* Was the fault on kernel-controlled part of the address space? */
- if (unlikely(fault_in_kernel_space(address)))
- do_kern_addr_fault(regs, hw_error_code, address);
- else
- do_user_addr_fault(regs, hw_error_code, address);
-}
-NOKPROBE_SYMBOL(__do_page_fault);
-
static __always_inline void
trace_page_fault_entries(struct pt_regs *regs, unsigned long error_code,
unsigned long address)
@@ -1522,13 +1501,19 @@ trace_page_fault_entries(struct pt_regs *regs, unsigned long error_code,
}
dotraplinkage void
-do_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address)
+do_page_fault(struct pt_regs *regs, unsigned long hw_error_code,
+ unsigned long address)
{
- enum ctx_state prev_state;
+ prefetchw(&current->mm->mmap_sem);
+ trace_page_fault_entries(regs, hw_error_code, address);
- prev_state = exception_enter();
- trace_page_fault_entries(regs, error_code, address);
- __do_page_fault(regs, error_code, address);
- exception_exit(prev_state);
+ if (unlikely(kmmio_fault(regs, address)))
+ return;
+
+ /* Was the fault on kernel-controlled part of the address space? */
+ if (unlikely(fault_in_kernel_space(address)))
+ do_kern_addr_fault(regs, hw_error_code, address);
+ else
+ do_user_addr_fault(regs, hw_error_code, address);
}
NOKPROBE_SYMBOL(do_page_fault);

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