Merge branch 'x86/asm' into locking/core

We need the ASM_UNREACHABLE() macro for a dependent patch.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/Kconfig.debug

@@ -305,8 +305,6 @@ config DEBUG_ENTRY
 	  Some of these sanity checks may slow down kernel entries and
 	  exits or otherwise impact performance.
 
-	  This is currently used to help test NMI code.
-
 	  If unsure, say N.
 
 config DEBUG_NMI_SELFTEST

arch/x86/entry/Makefile

@@ -2,7 +2,6 @@
 # Makefile for the x86 low level entry code
 #
 
-OBJECT_FILES_NON_STANDARD_entry_$(BITS).o   := y
 OBJECT_FILES_NON_STANDARD_entry_64_compat.o := y
 
 CFLAGS_syscall_64.o		+= $(call cc-option,-Wno-override-init,)

arch/x86/entry/calling.h

@@ -1,4 +1,5 @@
 #include <linux/jump_label.h>
+#include <asm/unwind_hints.h>
 
 /*
 
@@ -112,6 +113,7 @@ For 32-bit we have the following conventions - kernel is built with
 	movq %rdx, 12*8+\offset(%rsp)
 	movq %rsi, 13*8+\offset(%rsp)
 	movq %rdi, 14*8+\offset(%rsp)
+	UNWIND_HINT_REGS offset=\offset extra=0
 	.endm
 	.macro SAVE_C_REGS offset=0
 	SAVE_C_REGS_HELPER \offset, 1, 1, 1, 1
@@ -136,6 +138,7 @@ For 32-bit we have the following conventions - kernel is built with
 	movq %r12, 3*8+\offset(%rsp)
 	movq %rbp, 4*8+\offset(%rsp)
 	movq %rbx, 5*8+\offset(%rsp)
+	UNWIND_HINT_REGS offset=\offset
 	.endm
 
 	.macro RESTORE_EXTRA_REGS offset=0
@@ -145,6 +148,7 @@ For 32-bit we have the following conventions - kernel is built with
 	movq 3*8+\offset(%rsp), %r12
 	movq 4*8+\offset(%rsp), %rbp
 	movq 5*8+\offset(%rsp), %rbx
+	UNWIND_HINT_REGS offset=\offset extra=0
 	.endm
 
 	.macro RESTORE_C_REGS_HELPER rstor_rax=1, rstor_rcx=1, rstor_r11=1, rstor_r8910=1, rstor_rdx=1
@@ -167,6 +171,7 @@ For 32-bit we have the following conventions - kernel is built with
 	.endif
 	movq 13*8(%rsp), %rsi
 	movq 14*8(%rsp), %rdi
+	UNWIND_HINT_IRET_REGS offset=16*8
 	.endm
 	.macro RESTORE_C_REGS
 	RESTORE_C_REGS_HELPER 1,1,1,1,1

arch/x86/entry/entry_64.S

@@ -36,6 +36,7 @@
 #include <asm/smap.h>
 #include <asm/pgtable_types.h>
 #include <asm/export.h>
+#include <asm/frame.h>
 #include <linux/err.h>
 
 .code64
@@ -43,9 +44,10 @@
 
 #ifdef CONFIG_PARAVIRT
 ENTRY(native_usergs_sysret64)
+	UNWIND_HINT_EMPTY
 	swapgs
 	sysretq
-ENDPROC(native_usergs_sysret64)
+END(native_usergs_sysret64)
 #endif /* CONFIG_PARAVIRT */
 
 .macro TRACE_IRQS_IRETQ
@@ -134,6 +136,7 @@ ENDPROC(native_usergs_sysret64)
  */
 
 ENTRY(entry_SYSCALL_64)
+	UNWIND_HINT_EMPTY
 	/*
 	 * Interrupts are off on entry.
 	 * We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON,
@@ -169,6 +172,7 @@ GLOBAL(entry_SYSCALL_64_after_swapgs)
 	pushq	%r10				/* pt_regs->r10 */
 	pushq	%r11				/* pt_regs->r11 */
 	sub	$(6*8), %rsp			/* pt_regs->bp, bx, r12-15 not saved */
+	UNWIND_HINT_REGS extra=0
 
 	/*
 	 * If we need to do entry work or if we guess we'll need to do
@@ -223,6 +227,7 @@ entry_SYSCALL_64_fastpath:
 	movq	EFLAGS(%rsp), %r11
 	RESTORE_C_REGS_EXCEPT_RCX_R11
 	movq	RSP(%rsp), %rsp
+	UNWIND_HINT_EMPTY
 	USERGS_SYSRET64
 
 1:
@@ -316,6 +321,7 @@ syscall_return_via_sysret:
 	/* rcx and r11 are already restored (see code above) */
 	RESTORE_C_REGS_EXCEPT_RCX_R11
 	movq	RSP(%rsp), %rsp
+	UNWIND_HINT_EMPTY
 	USERGS_SYSRET64
 
 opportunistic_sysret_failed:
@@ -343,6 +349,7 @@ ENTRY(stub_ptregs_64)
 	DISABLE_INTERRUPTS(CLBR_ANY)
 	TRACE_IRQS_OFF
 	popq	%rax
+	UNWIND_HINT_REGS extra=0
 	jmp	entry_SYSCALL64_slow_path
 
 1:
@@ -351,6 +358,7 @@ END(stub_ptregs_64)
 
 .macro ptregs_stub func
 ENTRY(ptregs_\func)
+	UNWIND_HINT_FUNC
 	leaq	\func(%rip), %rax
 	jmp	stub_ptregs_64
 END(ptregs_\func)
@@ -367,6 +375,7 @@ END(ptregs_\func)
  * %rsi: next task
  */
 ENTRY(__switch_to_asm)
+	UNWIND_HINT_FUNC
 	/*
 	 * Save callee-saved registers
 	 * This must match the order in inactive_task_frame
@@ -406,6 +415,7 @@ END(__switch_to_asm)
  * r12: kernel thread arg
  */
 ENTRY(ret_from_fork)
+	UNWIND_HINT_EMPTY
 	movq	%rax, %rdi
 	call	schedule_tail			/* rdi: 'prev' task parameter */
 
@@ -413,6 +423,7 @@ ENTRY(ret_from_fork)
 	jnz	1f				/* kernel threads are uncommon */
 
 2:
+	UNWIND_HINT_REGS
 	movq	%rsp, %rdi
 	call	syscall_return_slowpath	/* returns with IRQs disabled */
 	TRACE_IRQS_ON			/* user mode is traced as IRQS on */
@@ -440,13 +451,102 @@ END(ret_from_fork)
 ENTRY(irq_entries_start)
     vector=FIRST_EXTERNAL_VECTOR
     .rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR)
+	UNWIND_HINT_IRET_REGS
 	pushq	$(~vector+0x80)			/* Note: always in signed byte range */
-    vector=vector+1
 	jmp	common_interrupt
 	.align	8
+	vector=vector+1
     .endr
 END(irq_entries_start)
 
+.macro DEBUG_ENTRY_ASSERT_IRQS_OFF
+#ifdef CONFIG_DEBUG_ENTRY
+	pushfq
+	testl $X86_EFLAGS_IF, (%rsp)
+	jz .Lokay_\@
+	ud2
+.Lokay_\@:
+	addq $8, %rsp
+#endif
+.endm
+
+/*
+ * Enters the IRQ stack if we're not already using it.  NMI-safe.  Clobbers
+ * flags and puts old RSP into old_rsp, and leaves all other GPRs alone.
+ * Requires kernel GSBASE.
+ *
+ * The invariant is that, if irq_count != -1, then the IRQ stack is in use.
+ */
+.macro ENTER_IRQ_STACK regs=1 old_rsp
+	DEBUG_ENTRY_ASSERT_IRQS_OFF
+	movq	%rsp, \old_rsp
+
+	.if \regs
+	UNWIND_HINT_REGS base=\old_rsp
+	.endif
+
+	incl	PER_CPU_VAR(irq_count)
+	jnz	.Lirq_stack_push_old_rsp_\@
+
+	/*
+	 * Right now, if we just incremented irq_count to zero, we've
+	 * claimed the IRQ stack but we haven't switched to it yet.
+	 *
+	 * If anything is added that can interrupt us here without using IST,
+	 * it must be *extremely* careful to limit its stack usage.  This
+	 * could include kprobes and a hypothetical future IST-less #DB
+	 * handler.
+	 *
+	 * The OOPS unwinder relies on the word at the top of the IRQ
+	 * stack linking back to the previous RSP for the entire time we're
+	 * on the IRQ stack.  For this to work reliably, we need to write
+	 * it before we actually move ourselves to the IRQ stack.
+	 */
+
+	movq	\old_rsp, PER_CPU_VAR(irq_stack_union + IRQ_STACK_SIZE - 8)
+	movq	PER_CPU_VAR(irq_stack_ptr), %rsp
+
+#ifdef CONFIG_DEBUG_ENTRY
+	/*
+	 * If the first movq above becomes wrong due to IRQ stack layout
+	 * changes, the only way we'll notice is if we try to unwind right
+	 * here.  Assert that we set up the stack right to catch this type
+	 * of bug quickly.
+	 */
+	cmpq	-8(%rsp), \old_rsp
+	je	.Lirq_stack_okay\@
+	ud2
+	.Lirq_stack_okay\@:
+#endif
+
+.Lirq_stack_push_old_rsp_\@:
+	pushq	\old_rsp
+
+	.if \regs
+	UNWIND_HINT_REGS indirect=1
+	.endif
+.endm
+
+/*
+ * Undoes ENTER_IRQ_STACK.
+ */
+.macro LEAVE_IRQ_STACK regs=1
+	DEBUG_ENTRY_ASSERT_IRQS_OFF
+	/* We need to be off the IRQ stack before decrementing irq_count. */
+	popq	%rsp
+
+	.if \regs
+	UNWIND_HINT_REGS
+	.endif
+
+	/*
+	 * As in ENTER_IRQ_STACK, irq_count == 0, we are still claiming
+	 * the irq stack but we're not on it.
+	 */
+
+	decl	PER_CPU_VAR(irq_count)
+.endm
+
 /*
  * Interrupt entry/exit.
  *
@@ -485,17 +585,7 @@ END(irq_entries_start)
 	CALL_enter_from_user_mode
 
 1:
-	/*
-	 * Save previous stack pointer, optionally switch to interrupt stack.
-	 * irq_count is used to check if a CPU is already on an interrupt stack
-	 * or not. While this is essentially redundant with preempt_count it is
-	 * a little cheaper to use a separate counter in the PDA (short of
-	 * moving irq_enter into assembly, which would be too much work)
-	 */
-	movq	%rsp, %rdi
-	incl	PER_CPU_VAR(irq_count)
-	cmovzq	PER_CPU_VAR(irq_stack_ptr), %rsp
-	pushq	%rdi
+	ENTER_IRQ_STACK old_rsp=%rdi
 	/* We entered an interrupt context - irqs are off: */
 	TRACE_IRQS_OFF
 
@@ -515,10 +605,8 @@ common_interrupt:
 ret_from_intr:
 	DISABLE_INTERRUPTS(CLBR_ANY)
 	TRACE_IRQS_OFF
-	decl	PER_CPU_VAR(irq_count)
 
-	/* Restore saved previous stack */
-	popq	%rsp
+	LEAVE_IRQ_STACK
 
 	testb	$3, CS(%rsp)
 	jz	retint_kernel
@@ -561,6 +649,7 @@ restore_c_regs_and_iret:
 	INTERRUPT_RETURN
 
 ENTRY(native_iret)
+	UNWIND_HINT_IRET_REGS
 	/*
 	 * Are we returning to a stack segment from the LDT?  Note: in
 	 * 64-bit mode SS:RSP on the exception stack is always valid.
@@ -633,6 +722,7 @@ native_irq_return_ldt:
 	orq	PER_CPU_VAR(espfix_stack), %rax
 	SWAPGS
 	movq	%rax, %rsp
+	UNWIND_HINT_IRET_REGS offset=8
 
 	/*
 	 * At this point, we cannot write to the stack any more, but we can
@@ -654,6 +744,7 @@ END(common_interrupt)
  */
 .macro apicinterrupt3 num sym do_sym
 ENTRY(\sym)
+	UNWIND_HINT_IRET_REGS
 	ASM_CLAC
 	pushq	$~(\num)
 .Lcommon_\sym:
@@ -740,6 +831,8 @@ apicinterrupt IRQ_WORK_VECTOR			irq_work_interrupt		smp_irq_work_interrupt
 
 .macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1
 ENTRY(\sym)
+	UNWIND_HINT_IRET_REGS offset=8
+
 	/* Sanity check */
 	.if \shift_ist != -1 && \paranoid == 0
 	.error "using shift_ist requires paranoid=1"
@@ -763,6 +856,7 @@ ENTRY(\sym)
 	.else
 	call	error_entry
 	.endif
+	UNWIND_HINT_REGS
 	/* returned flag: ebx=0: need swapgs on exit, ebx=1: don't need it */
 
 	.if \paranoid
@@ -860,6 +954,7 @@ idtentry simd_coprocessor_error		do_simd_coprocessor_error	has_error_code=0
 	 * edi:  new selector
 	 */
 ENTRY(native_load_gs_index)
+	FRAME_BEGIN
 	pushfq
 	DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI)
 	SWAPGS
@@ -868,8 +963,9 @@ ENTRY(native_load_gs_index)
 2:	ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE
 	SWAPGS
 	popfq
+	FRAME_END
 	ret
-END(native_load_gs_index)
+ENDPROC(native_load_gs_index)
 EXPORT_SYMBOL(native_load_gs_index)
 
 	_ASM_EXTABLE(.Lgs_change, bad_gs)
@@ -892,14 +988,12 @@ bad_gs:
 ENTRY(do_softirq_own_stack)
 	pushq	%rbp
 	mov	%rsp, %rbp
-	incl	PER_CPU_VAR(irq_count)
-	cmove	PER_CPU_VAR(irq_stack_ptr), %rsp
-	push	%rbp				/* frame pointer backlink */
+	ENTER_IRQ_STACK regs=0 old_rsp=%r11
 	call	__do_softirq
+	LEAVE_IRQ_STACK regs=0
 	leaveq
-	decl	PER_CPU_VAR(irq_count)
 	ret
-END(do_softirq_own_stack)
+ENDPROC(do_softirq_own_stack)
 
 #ifdef CONFIG_XEN
 idtentry xen_hypervisor_callback xen_do_hypervisor_callback has_error_code=0
@@ -923,14 +1017,14 @@ ENTRY(xen_do_hypervisor_callback)		/* do_hypervisor_callback(struct *pt_regs) */
  * Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will
  * see the correct pointer to the pt_regs
  */
+	UNWIND_HINT_FUNC
 	movq	%rdi, %rsp			/* we don't return, adjust the stack frame */
-11:	incl	PER_CPU_VAR(irq_count)
-	movq	%rsp, %rbp
-	cmovzq	PER_CPU_VAR(irq_stack_ptr), %rsp
-	pushq	%rbp				/* frame pointer backlink */
+	UNWIND_HINT_REGS
+
+	ENTER_IRQ_STACK old_rsp=%r10
 	call	xen_evtchn_do_upcall
-	popq	%rsp
-	decl	PER_CPU_VAR(irq_count)
+	LEAVE_IRQ_STACK
+
 #ifndef CONFIG_PREEMPT
 	call	xen_maybe_preempt_hcall
 #endif
@@ -951,6 +1045,7 @@ END(xen_do_hypervisor_callback)
  * with its current contents: any discrepancy means we in category 1.
  */
 ENTRY(xen_failsafe_callback)
+	UNWIND_HINT_EMPTY
 	movl	%ds, %ecx
 	cmpw	%cx, 0x10(%rsp)
 	jne	1f
@@ -970,11 +1065,13 @@ ENTRY(xen_failsafe_callback)
 	pushq	$0				/* RIP */
 	pushq	%r11
 	pushq	%rcx
+	UNWIND_HINT_IRET_REGS offset=8
 	jmp	general_protection
 1:	/* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */
 	movq	(%rsp), %rcx
 	movq	8(%rsp), %r11
 	addq	$0x30, %rsp
+	UNWIND_HINT_IRET_REGS
 	pushq	$-1 /* orig_ax = -1 => not a system call */
 	ALLOC_PT_GPREGS_ON_STACK
 	SAVE_C_REGS
@@ -1020,6 +1117,7 @@ idtentry machine_check					has_error_code=0	paranoid=1 do_sym=*machine_check_vec
  * Return: ebx=0: need swapgs on exit, ebx=1: otherwise
  */
 ENTRY(paranoid_entry)
+	UNWIND_HINT_FUNC
 	cld
 	SAVE_C_REGS 8
 	SAVE_EXTRA_REGS 8
@@ -1047,6 +1145,7 @@ END(paranoid_entry)
  * On entry, ebx is "no swapgs" flag (1: don't need swapgs, 0: need it)
  */
 ENTRY(paranoid_exit)
+	UNWIND_HINT_REGS
 	DISABLE_INTERRUPTS(CLBR_ANY)
 	TRACE_IRQS_OFF_DEBUG
 	testl	%ebx, %ebx			/* swapgs needed? */
@@ -1068,6 +1167,7 @@ END(paranoid_exit)
  * Return: EBX=0: came from user mode; EBX=1: otherwise
  */
 ENTRY(error_entry)
+	UNWIND_HINT_FUNC
 	cld
 	SAVE_C_REGS 8
 	SAVE_EXTRA_REGS 8
@@ -1152,6 +1252,7 @@ END(error_entry)
  *   0: user gsbase is loaded, we need SWAPGS and standard preparation for return to usermode
  */
 ENTRY(error_exit)
+	UNWIND_HINT_REGS
 	DISABLE_INTERRUPTS(CLBR_ANY)
 	TRACE_IRQS_OFF
 	testl	%ebx, %ebx
@@ -1161,6 +1262,7 @@ END(error_exit)
 
 /* Runs on exception stack */
 ENTRY(nmi)
+	UNWIND_HINT_IRET_REGS
 	/*
 	 * Fix up the exception frame if we're on Xen.
 	 * PARAVIRT_ADJUST_EXCEPTION_FRAME is guaranteed to push at most
@@ -1232,11 +1334,13 @@ ENTRY(nmi)
 	cld
 	movq	%rsp, %rdx
 	movq	PER_CPU_VAR(cpu_current_top_of_stack), %rsp
+	UNWIND_HINT_IRET_REGS base=%rdx offset=8
 	pushq	5*8(%rdx)	/* pt_regs->ss */
 	pushq	4*8(%rdx)	/* pt_regs->rsp */
 	pushq	3*8(%rdx)	/* pt_regs->flags */
 	pushq	2*8(%rdx)	/* pt_regs->cs */
 	pushq	1*8(%rdx)	/* pt_regs->rip */
+	UNWIND_HINT_IRET_REGS
 	pushq   $-1		/* pt_regs->orig_ax */
 	pushq   %rdi		/* pt_regs->di */
 	pushq   %rsi		/* pt_regs->si */
@@ -1253,6 +1357,7 @@ ENTRY(nmi)
 	pushq	%r13		/* pt_regs->r13 */
 	pushq	%r14		/* pt_regs->r14 */
 	pushq	%r15		/* pt_regs->r15 */
+	UNWIND_HINT_REGS
 	ENCODE_FRAME_POINTER
 
 	/*
@@ -1407,6 +1512,7 @@ first_nmi:
 	.rept 5
 	pushq	11*8(%rsp)
 	.endr
+	UNWIND_HINT_IRET_REGS
 
 	/* Everything up to here is safe from nested NMIs */
 
@@ -1422,6 +1528,7 @@ first_nmi:
 	pushq	$__KERNEL_CS	/* CS */
 	pushq	$1f		/* RIP */
 	INTERRUPT_RETURN	/* continues at repeat_nmi below */
+	UNWIND_HINT_IRET_REGS
 1:
 #endif
 
@@ -1471,6 +1578,7 @@ end_repeat_nmi:
 	 * exceptions might do.
 	 */
 	call	paranoid_entry
+	UNWIND_HINT_REGS
 
 	/* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */
 	movq	%rsp, %rdi
@@ -1508,17 +1616,19 @@ nmi_restore:
 END(nmi)
 
 ENTRY(ignore_sysret)
+	UNWIND_HINT_EMPTY
 	mov	$-ENOSYS, %eax
 	sysret
 END(ignore_sysret)
 
 ENTRY(rewind_stack_do_exit)
+	UNWIND_HINT_FUNC
 	/* Prevent any naive code from trying to unwind to our caller. */
 	xorl	%ebp, %ebp
 
 	movq	PER_CPU_VAR(cpu_current_top_of_stack), %rax
-	leaq	-TOP_OF_KERNEL_STACK_PADDING-PTREGS_SIZE(%rax), %rsp
+	leaq	-PTREGS_SIZE(%rax), %rsp
+	UNWIND_HINT_FUNC sp_offset=PTREGS_SIZE
 
 	call	do_exit
-1:	jmp 1b
 END(rewind_stack_do_exit)

arch/x86/include/asm/io.h

@@ -69,6 +69,9 @@ build_mmio_write(__writeb, "b", unsigned char, "q", )
 build_mmio_write(__writew, "w", unsigned short, "r", )
 build_mmio_write(__writel, "l", unsigned int, "r", )
 
+#define readb readb
+#define readw readw
+#define readl readl
 #define readb_relaxed(a) __readb(a)
 #define readw_relaxed(a) __readw(a)
 #define readl_relaxed(a) __readl(a)
@@ -76,6 +79,9 @@ build_mmio_write(__writel, "l", unsigned int, "r", )
 #define __raw_readw __readw
 #define __raw_readl __readl
 
+#define writeb writeb
+#define writew writew
+#define writel writel
 #define writeb_relaxed(v, a) __writeb(v, a)
 #define writew_relaxed(v, a) __writew(v, a)
 #define writel_relaxed(v, a) __writel(v, a)
@@ -88,13 +94,15 @@ build_mmio_write(__writel, "l", unsigned int, "r", )
 #ifdef CONFIG_X86_64
 
 build_mmio_read(readq, "q", unsigned long, "=r", :"memory")
+build_mmio_read(__readq, "q", unsigned long, "=r", )
 build_mmio_write(writeq, "q", unsigned long, "r", :"memory")
+build_mmio_write(__writeq, "q", unsigned long, "r", )
 
-#define readq_relaxed(a)	readq(a)
-#define writeq_relaxed(v, a)	writeq(v, a)
+#define readq_relaxed(a)	__readq(a)
+#define writeq_relaxed(v, a)	__writeq(v, a)
 
-#define __raw_readq(a)		readq(a)
-#define __raw_writeq(val, addr)	writeq(val, addr)
+#define __raw_readq		__readq
+#define __raw_writeq		__writeq
 
 /* Let people know that we have them */
 #define readq			readq
@@ -119,6 +127,7 @@ static inline phys_addr_t virt_to_phys(volatile void *address)
 {
 	return __pa(address);
 }
+#define virt_to_phys virt_to_phys
 
 /**
  *	phys_to_virt	-	map physical address to virtual
@@ -137,6 +146,7 @@ static inline void *phys_to_virt(phys_addr_t address)
 {
 	return __va(address);
 }
+#define phys_to_virt phys_to_virt
 
 /*
  * Change "struct page" to physical address.
@@ -169,11 +179,14 @@ static inline unsigned int isa_virt_to_bus(volatile void *address)
  * else, you probably want one of the following.
  */
 extern void __iomem *ioremap_nocache(resource_size_t offset, unsigned long size);
+#define ioremap_nocache ioremap_nocache
 extern void __iomem *ioremap_uc(resource_size_t offset, unsigned long size);
 #define ioremap_uc ioremap_uc
 
 extern void __iomem *ioremap_cache(resource_size_t offset, unsigned long size);
+#define ioremap_cache ioremap_cache
 extern void __iomem *ioremap_prot(resource_size_t offset, unsigned long size, unsigned long prot_val);
+#define ioremap_prot ioremap_prot
 
 /**
  * ioremap     -   map bus memory into CPU space
@@ -193,8 +206,10 @@ static inline void __iomem *ioremap(resource_size_t offset, unsigned long size)
 {
 	return ioremap_nocache(offset, size);
 }
+#define ioremap ioremap
 
 extern void iounmap(volatile void __iomem *addr);
+#define iounmap iounmap
 
 extern void set_iounmap_nonlazy(void);
 
@@ -202,53 +217,6 @@ extern void set_iounmap_nonlazy(void);
 
 #include <asm-generic/iomap.h>
 
-/*
- * Convert a virtual cached pointer to an uncached pointer
- */
-#define xlate_dev_kmem_ptr(p)	p
-
-/**
- * memset_io	Set a range of I/O memory to a constant value
- * @addr:	The beginning of the I/O-memory range to set
- * @val:	The value to set the memory to
- * @count:	The number of bytes to set
- *
- * Set a range of I/O memory to a given value.
- */
-static inline void
-memset_io(volatile void __iomem *addr, unsigned char val, size_t count)
-{
-	memset((void __force *)addr, val, count);
-}
-
-/**
- * memcpy_fromio	Copy a block of data from I/O memory
- * @dst:		The (RAM) destination for the copy
- * @src:		The (I/O memory) source for the data
- * @count:		The number of bytes to copy
- *
- * Copy a block of data from I/O memory.
- */
-static inline void
-memcpy_fromio(void *dst, const volatile void __iomem *src, size_t count)
-{
-	memcpy(dst, (const void __force *)src, count);
-}
-
-/**
- * memcpy_toio		Copy a block of data into I/O memory
- * @dst:		The (I/O memory) destination for the copy
- * @src:		The (RAM) source for the data
- * @count:		The number of bytes to copy
- *
- * Copy a block of data to I/O memory.
- */
-static inline void
-memcpy_toio(volatile void __iomem *dst, const void *src, size_t count)
-{
-	memcpy((void __force *)dst, src, count);
-}
-
 /*
  * ISA space is 'always mapped' on a typical x86 system, no need to
  * explicitly ioremap() it. The fact that the ISA IO space is mapped
@@ -341,13 +309,38 @@ BUILDIO(b, b, char)
 BUILDIO(w, w, short)
 BUILDIO(l, , int)
 
+#define inb inb
+#define inw inw
+#define inl inl
+#define inb_p inb_p
+#define inw_p inw_p
+#define inl_p inl_p
+#define insb insb
+#define insw insw
+#define insl insl
+
+#define outb outb
+#define outw outw
+#define outl outl
+#define outb_p outb_p
+#define outw_p outw_p
+#define outl_p outl_p
+#define outsb outsb
+#define outsw outsw
+#define outsl outsl
+
 extern void *xlate_dev_mem_ptr(phys_addr_t phys);
 extern void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr);
 
+#define xlate_dev_mem_ptr xlate_dev_mem_ptr
+#define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
+
 extern int ioremap_change_attr(unsigned long vaddr, unsigned long size,
 				enum page_cache_mode pcm);
 extern void __iomem *ioremap_wc(resource_size_t offset, unsigned long size);
+#define ioremap_wc ioremap_wc
 extern void __iomem *ioremap_wt(resource_size_t offset, unsigned long size);
+#define ioremap_wt ioremap_wt
 
 extern bool is_early_ioremap_ptep(pte_t *ptep);
 
@@ -365,6 +358,9 @@ extern bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
 
 #define IO_SPACE_LIMIT 0xffff
 
+#include <asm-generic/io.h>
+#undef PCI_IOBASE
+
 #ifdef CONFIG_MTRR
 extern int __must_check arch_phys_wc_index(int handle);
 #define arch_phys_wc_index arch_phys_wc_index

arch/x86/include/asm/orc_types.h

@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _ORC_TYPES_H
+#define _ORC_TYPES_H
+
+#include <linux/types.h>
+#include <linux/compiler.h>
+
+/*
+ * The ORC_REG_* registers are base registers which are used to find other
+ * registers on the stack.
+ *
+ * ORC_REG_PREV_SP, also known as DWARF Call Frame Address (CFA), is the
+ * address of the previous frame: the caller's SP before it called the current
+ * function.
+ *
+ * ORC_REG_UNDEFINED means the corresponding register's value didn't change in
+ * the current frame.
+ *
+ * The most commonly used base registers are SP and BP -- which the previous SP
+ * is usually based on -- and PREV_SP and UNDEFINED -- which the previous BP is
+ * usually based on.
+ *
+ * The rest of the base registers are needed for special cases like entry code
+ * and GCC realigned stacks.
+ */
+#define ORC_REG_UNDEFINED		0
+#define ORC_REG_PREV_SP			1
+#define ORC_REG_DX			2
+#define ORC_REG_DI			3
+#define ORC_REG_BP			4
+#define ORC_REG_SP			5
+#define ORC_REG_R10			6
+#define ORC_REG_R13			7
+#define ORC_REG_BP_INDIRECT		8
+#define ORC_REG_SP_INDIRECT		9
+#define ORC_REG_MAX			15
+
+/*
+ * ORC_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP (the
+ * caller's SP right before it made the call).  Used for all callable
+ * functions, i.e. all C code and all callable asm functions.
+ *
+ * ORC_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset points
+ * to a fully populated pt_regs from a syscall, interrupt, or exception.
+ *
+ * ORC_TYPE_REGS_IRET: Used in entry code to indicate that sp_reg+sp_offset
+ * points to the iret return frame.
+ *
+ * The UNWIND_HINT macros are used only for the unwind_hint struct.  They
+ * aren't used in struct orc_entry due to size and complexity constraints.
+ * Objtool converts them to real types when it converts the hints to orc
+ * entries.
+ */
+#define ORC_TYPE_CALL			0
+#define ORC_TYPE_REGS			1
+#define ORC_TYPE_REGS_IRET		2
+#define UNWIND_HINT_TYPE_SAVE		3
+#define UNWIND_HINT_TYPE_RESTORE	4
+
+#ifndef __ASSEMBLY__
+/*
+ * This struct is more or less a vastly simplified version of the DWARF Call
+ * Frame Information standard.  It contains only the necessary parts of DWARF
+ * CFI, simplified for ease of access by the in-kernel unwinder.  It tells the
+ * unwinder how to find the previous SP and BP (and sometimes entry regs) on
+ * the stack for a given code address.  Each instance of the struct corresponds
+ * to one or more code locations.
+ */
+struct orc_entry {
+	s16		sp_offset;
+	s16		bp_offset;
+	unsigned	sp_reg:4;
+	unsigned	bp_reg:4;
+	unsigned	type:2;
+};
+
+/*
+ * This struct is used by asm and inline asm code to manually annotate the
+ * location of registers on the stack for the ORC unwinder.
+ *
+ * Type can be either ORC_TYPE_* or UNWIND_HINT_TYPE_*.
+ */
+struct unwind_hint {
+	u32		ip;
+	s16		sp_offset;
+	u8		sp_reg;
+	u8		type;
+};
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ORC_TYPES_H */

arch/x86/include/asm/processor.h

@@ -22,6 +22,7 @@ struct vm86;
 #include <asm/nops.h>
 #include <asm/special_insns.h>
 #include <asm/fpu/types.h>
+#include <asm/unwind_hints.h>
 
 #include <linux/personality.h>
 #include <linux/cache.h>
@@ -684,6 +685,7 @@ static inline void sync_core(void)
 	unsigned int tmp;
 
 	asm volatile (
+		UNWIND_HINT_SAVE
 		"mov %%ss, %0\n\t"
 		"pushq %q0\n\t"
 		"pushq %%rsp\n\t"
@@ -693,6 +695,7 @@ static inline void sync_core(void)
 		"pushq %q0\n\t"
 		"pushq $1f\n\t"
 		"iretq\n\t"
+		UNWIND_HINT_RESTORE
 		"1:"
 		: "=&r" (tmp), "+r" (__sp) : : "cc", "memory");
 #endif

arch/x86/include/asm/rmwcc.h

@@ -1,45 +1,56 @@
 #ifndef _ASM_X86_RMWcc
 #define _ASM_X86_RMWcc
 
+#define __CLOBBERS_MEM		"memory"
+#define __CLOBBERS_MEM_CC_CX	"memory", "cc", "cx"
+
 #if !defined(__GCC_ASM_FLAG_OUTPUTS__) && defined(CC_HAVE_ASM_GOTO)
 
 /* Use asm goto */
 
-#define __GEN_RMWcc(fullop, var, cc, ...)				\
+#define __GEN_RMWcc(fullop, var, cc, clobbers, ...)			\
 do {									\
 	asm_volatile_goto (fullop "; j" #cc " %l[cc_label]"		\
-			: : "m" (var), ## __VA_ARGS__ 			\
-			: "memory" : cc_label);				\
+			: : [counter] "m" (var), ## __VA_ARGS__		\
+			: clobbers : cc_label);				\
 	return 0;							\
 cc_label:								\
 	return 1;							\
 } while (0)
 
-#define GEN_UNARY_RMWcc(op, var, arg0, cc) 				\
-	__GEN_RMWcc(op " " arg0, var, cc)
+#define __BINARY_RMWcc_ARG	" %1, "
 
-#define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc)			\
-	__GEN_RMWcc(op " %1, " arg0, var, cc, vcon (val))
 
 #else /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */
 
 /* Use flags output or a set instruction */
 
-#define __GEN_RMWcc(fullop, var, cc, ...)				\
+#define __GEN_RMWcc(fullop, var, cc, clobbers, ...)			\
 do {									\
 	bool c;								\
 	asm volatile (fullop ";" CC_SET(cc)				\
-			: "+m" (var), CC_OUT(cc) (c)			\
-			: __VA_ARGS__ : "memory");			\
+			: [counter] "+m" (var), CC_OUT(cc) (c)		\
+			: __VA_ARGS__ : clobbers);			\
 	return c;							\
 } while (0)
 
-#define GEN_UNARY_RMWcc(op, var, arg0, cc)				\
-	__GEN_RMWcc(op " " arg0, var, cc)
-
-#define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc)			\
-	__GEN_RMWcc(op " %2, " arg0, var, cc, vcon (val))
+#define __BINARY_RMWcc_ARG	" %2, "
 
 #endif /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */
 
+#define GEN_UNARY_RMWcc(op, var, arg0, cc)				\
+	__GEN_RMWcc(op " " arg0, var, cc, __CLOBBERS_MEM)
+
+#define GEN_UNARY_SUFFIXED_RMWcc(op, suffix, var, arg0, cc)		\
+	__GEN_RMWcc(op " " arg0 "\n\t" suffix, var, cc,			\
+		    __CLOBBERS_MEM_CC_CX)
+
+#define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc)			\
+	__GEN_RMWcc(op __BINARY_RMWcc_ARG arg0, var, cc,		\
+		    __CLOBBERS_MEM, vcon (val))
+
+#define GEN_BINARY_SUFFIXED_RMWcc(op, suffix, var, vcon, val, arg0, cc)	\
+	__GEN_RMWcc(op __BINARY_RMWcc_ARG arg0 "\n\t" suffix, var, cc,	\
+		    __CLOBBERS_MEM_CC_CX, vcon (val))
+
 #endif /* _ASM_X86_RMWcc */

arch/x86/include/asm/unwind_hints.h

@@ -0,0 +1,103 @@
+#ifndef _ASM_X86_UNWIND_HINTS_H
+#define _ASM_X86_UNWIND_HINTS_H
+
+#include "orc_types.h"
+
+#ifdef __ASSEMBLY__
+
+/*
+ * In asm, there are two kinds of code: normal C-type callable functions and
+ * the rest.  The normal callable functions can be called by other code, and
+ * don't do anything unusual with the stack.  Such normal callable functions
+ * are annotated with the ENTRY/ENDPROC macros.  Most asm code falls in this
+ * category.  In this case, no special debugging annotations are needed because
+ * objtool can automatically generate the ORC data for the ORC unwinder to read
+ * at runtime.
+ *
+ * Anything which doesn't fall into the above category, such as syscall and
+ * interrupt handlers, tends to not be called directly by other functions, and
+ * often does unusual non-C-function-type things with the stack pointer.  Such
+ * code needs to be annotated such that objtool can understand it.  The
+ * following CFI hint macros are for this type of code.
+ *
+ * These macros provide hints to objtool about the state of the stack at each
+ * instruction.  Objtool starts from the hints and follows the code flow,
+ * making automatic CFI adjustments when it sees pushes and pops, filling out
+ * the debuginfo as necessary.  It will also warn if it sees any
+ * inconsistencies.
+ */
+.macro UNWIND_HINT sp_reg=ORC_REG_SP sp_offset=0 type=ORC_TYPE_CALL
+#ifdef CONFIG_STACK_VALIDATION
+.Lunwind_hint_ip_\@:
+	.pushsection .discard.unwind_hints
+		/* struct unwind_hint */
+		.long .Lunwind_hint_ip_\@ - .
+		.short \sp_offset
+		.byte \sp_reg
+		.byte \type
+	.popsection
+#endif
+.endm
+
+.macro UNWIND_HINT_EMPTY
+	UNWIND_HINT sp_reg=ORC_REG_UNDEFINED
+.endm
+
+.macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 iret=0
+	.if \base == %rsp && \indirect
+		.set sp_reg, ORC_REG_SP_INDIRECT
+	.elseif \base == %rsp
+		.set sp_reg, ORC_REG_SP
+	.elseif \base == %rbp
+		.set sp_reg, ORC_REG_BP
+	.elseif \base == %rdi
+		.set sp_reg, ORC_REG_DI
+	.elseif \base == %rdx
+		.set sp_reg, ORC_REG_DX
+	.elseif \base == %r10
+		.set sp_reg, ORC_REG_R10
+	.else
+		.error "UNWIND_HINT_REGS: bad base register"
+	.endif
+
+	.set sp_offset, \offset
+
+	.if \iret
+		.set type, ORC_TYPE_REGS_IRET
+	.elseif \extra == 0
+		.set type, ORC_TYPE_REGS_IRET
+		.set sp_offset, \offset + (16*8)
+	.else
+		.set type, ORC_TYPE_REGS
+	.endif
+
+	UNWIND_HINT sp_reg=sp_reg sp_offset=sp_offset type=type
+.endm
+
+.macro UNWIND_HINT_IRET_REGS base=%rsp offset=0
+	UNWIND_HINT_REGS base=\base offset=\offset iret=1
+.endm
+
+.macro UNWIND_HINT_FUNC sp_offset=8
+	UNWIND_HINT sp_offset=\sp_offset
+.endm
+
+#else /* !__ASSEMBLY__ */
+
+#define UNWIND_HINT(sp_reg, sp_offset, type)			\
+	"987: \n\t"						\
+	".pushsection .discard.unwind_hints\n\t"		\
+	/* struct unwind_hint */				\
+	".long 987b - .\n\t"					\
+	".short " __stringify(sp_offset) "\n\t"		\
+	".byte " __stringify(sp_reg) "\n\t"			\
+	".byte " __stringify(type) "\n\t"			\
+	".popsection\n\t"
+
+#define UNWIND_HINT_SAVE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_SAVE)
+
+#define UNWIND_HINT_RESTORE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_RESTORE)
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_X86_UNWIND_HINTS_H */

arch/x86/kernel/dumpstack.c

@@ -94,6 +94,9 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 		if (stack_name)
 			printk("%s <%s>\n", log_lvl, stack_name);
 
+		if (regs && on_stack(&stack_info, regs, sizeof(*regs)))
+			__show_regs(regs, 0);
+
 		/*
 		 * Scan the stack, printing any text addresses we find.  At the
 		 * same time, follow proper stack frames with the unwinder.
@@ -118,10 +121,8 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 			 * Don't print regs->ip again if it was already printed
 			 * by __show_regs() below.
 			 */
-			if (regs && stack == &regs->ip) {
-				unwind_next_frame(&state);
-				continue;
-			}
+			if (regs && stack == &regs->ip)
+				goto next;
 
 			if (stack == ret_addr_p)
 				reliable = 1;
@@ -144,6 +145,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 			if (!reliable)
 				continue;
 
+next:
 			/*
 			 * Get the next frame from the unwinder.  No need to
 			 * check for an error: if anything goes wrong, the rest
@@ -153,7 +155,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 
 			/* if the frame has entry regs, print them */
 			regs = unwind_get_entry_regs(&state);
-			if (regs)
+			if (regs && on_stack(&stack_info, regs, sizeof(*regs)))
 				__show_regs(regs, 0);
 		}
 

arch/x86/kernel/dumpstack_32.c

@@ -37,7 +37,7 @@ static bool in_hardirq_stack(unsigned long *stack, struct stack_info *info)
 	 * This is a software stack, so 'end' can be a valid stack pointer.
 	 * It just means the stack is empty.
 	 */
-	if (stack < begin || stack > end)
+	if (stack <= begin || stack > end)
 		return false;
 
 	info->type	= STACK_TYPE_IRQ;
@@ -62,7 +62,7 @@ static bool in_softirq_stack(unsigned long *stack, struct stack_info *info)
 	 * This is a software stack, so 'end' can be a valid stack pointer.
 	 * It just means the stack is empty.
 	 */
-	if (stack < begin || stack > end)
+	if (stack <= begin || stack > end)
 		return false;
 
 	info->type	= STACK_TYPE_SOFTIRQ;

arch/x86/kernel/dumpstack_64.c

@@ -55,7 +55,7 @@ static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
 		begin = end - (exception_stack_sizes[k] / sizeof(long));
 		regs  = (struct pt_regs *)end - 1;
 
-		if (stack < begin || stack >= end)
+		if (stack <= begin || stack >= end)
 			continue;
 
 		info->type	= STACK_TYPE_EXCEPTION + k;
@@ -78,7 +78,7 @@ static bool in_irq_stack(unsigned long *stack, struct stack_info *info)
 	 * This is a software stack, so 'end' can be a valid stack pointer.
 	 * It just means the stack is empty.
 	 */
-	if (stack < begin || stack > end)
+	if (stack <= begin || stack > end)
 		return false;
 
 	info->type	= STACK_TYPE_IRQ;

arch/x86/kernel/process_64.c

@@ -279,6 +279,9 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 	struct tss_struct *tss = &per_cpu(cpu_tss, cpu);
 	unsigned prev_fsindex, prev_gsindex;
 
+	WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ENTRY) &&
+		     this_cpu_read(irq_count) != -1);
+
 	switch_fpu_prepare(prev_fpu, cpu);
 
 	/* We must save %fs and %gs before load_TLS() because

include/asm-generic/io.h

@@ -915,6 +915,9 @@ extern void ioport_unmap(void __iomem *p);
 #endif /* CONFIG_GENERIC_IOMAP */
 #endif /* CONFIG_HAS_IOPORT_MAP */
 
+/*
+ * Convert a virtual cached pointer to an uncached pointer
+ */
 #ifndef xlate_dev_kmem_ptr
 #define xlate_dev_kmem_ptr xlate_dev_kmem_ptr
 static inline void *xlate_dev_kmem_ptr(void *addr)
@@ -954,6 +957,14 @@ static inline void *bus_to_virt(unsigned long address)
 
 #ifndef memset_io
 #define memset_io memset_io
+/**
+ * memset_io	Set a range of I/O memory to a constant value
+ * @addr:	The beginning of the I/O-memory range to set
+ * @val:	The value to set the memory to
+ * @count:	The number of bytes to set
+ *
+ * Set a range of I/O memory to a given value.
+ */
 static inline void memset_io(volatile void __iomem *addr, int value,
 			     size_t size)
 {
@@ -963,6 +974,14 @@ static inline void memset_io(volatile void __iomem *addr, int value,
 
 #ifndef memcpy_fromio
 #define memcpy_fromio memcpy_fromio
+/**
+ * memcpy_fromio	Copy a block of data from I/O memory
+ * @dst:		The (RAM) destination for the copy
+ * @src:		The (I/O memory) source for the data
+ * @count:		The number of bytes to copy
+ *
+ * Copy a block of data from I/O memory.
+ */
 static inline void memcpy_fromio(void *buffer,
 				 const volatile void __iomem *addr,
 				 size_t size)
@@ -973,6 +992,14 @@ static inline void memcpy_fromio(void *buffer,
 
 #ifndef memcpy_toio
 #define memcpy_toio memcpy_toio
+/**
+ * memcpy_toio		Copy a block of data into I/O memory
+ * @dst:		The (I/O memory) destination for the copy
+ * @src:		The (RAM) source for the data
+ * @count:		The number of bytes to copy
+ *
+ * Copy a block of data to I/O memory.
+ */
 static inline void memcpy_toio(volatile void __iomem *addr, const void *buffer,
 			       size_t size)
 {

include/linux/compiler-gcc.h

@@ -203,11 +203,16 @@
 
 #ifdef CONFIG_STACK_VALIDATION
 #define annotate_unreachable() ({					\
-	asm("%c0:\t\n"							\
-	    ".pushsection .discard.unreachable\t\n"			\
-	    ".long %c0b - .\t\n"					\
-	    ".popsection\t\n" : : "i" (__LINE__));			\
+	asm("%c0:\n\t"							\
+	    ".pushsection .discard.unreachable\n\t"			\
+	    ".long %c0b - .\n\t"					\
+	    ".popsection\n\t" : : "i" (__LINE__));			\
 })
+#define ASM_UNREACHABLE							\
+	"999:\n\t"							\
+	".pushsection .discard.unreachable\n\t"				\
+	".long 999b - .\n\t"						\
+	".popsection\n\t"
 #else
 #define annotate_unreachable()
 #endif

include/linux/compiler.h

@@ -185,6 +185,9 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 #endif
 
 /* Unreachable code */
+#ifndef ASM_UNREACHABLE
+# define ASM_UNREACHABLE
+#endif
 #ifndef unreachable
 # define unreachable() do { } while (1)
 #endif

scripts/Makefile.build

@@ -262,6 +262,9 @@ objtool_args = check
 ifndef CONFIG_FRAME_POINTER
 objtool_args += --no-fp
 endif
+ifdef CONFIG_GCOV_KERNEL
+objtool_args += --no-unreachable
+endif
 
 # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory
 # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file

tools/objtool/Build

@@ -1,6 +1,9 @@
 objtool-y += arch/$(SRCARCH)/
 objtool-y += builtin-check.o
+objtool-y += builtin-orc.o
 objtool-y += check.o
+objtool-y += orc_gen.o
+objtool-y += orc_dump.o
 objtool-y += elf.o
 objtool-y += special.o
 objtool-y += objtool.o

tools/objtool/Documentation/stack-validation.txt

@@ -11,9 +11,6 @@ analyzes every .o file and ensures the validity of its stack metadata.
 It enforces a set of rules on asm code and C inline assembly code so
 that stack traces can be reliable.
 
-Currently it only checks frame pointer usage, but there are plans to add
-CFI validation for C files and CFI generation for asm files.
-
 For each function, it recursively follows all possible code paths and
 validates the correct frame pointer state at each instruction.
 
@@ -23,6 +20,10 @@ alternative execution paths to a given instruction (or set of
 instructions).  Similarly, it knows how to follow switch statements, for
 which gcc sometimes uses jump tables.
 
+(Objtool also has an 'orc generate' subcommand which generates debuginfo
+for the ORC unwinder.  See Documentation/x86/orc-unwinder.txt in the
+kernel tree for more details.)
+
 
 Why do we need stack metadata validation?
 -----------------------------------------
@@ -93,37 +94,14 @@ a) More reliable stack traces for frame pointer enabled kernels
        or at the very end of the function after the stack frame has been
        destroyed.  This is an inherent limitation of frame pointers.
 
-b) 100% reliable stack traces for DWARF enabled kernels
+b) ORC (Oops Rewind Capability) unwind table generation
 
-   (NOTE: This is not yet implemented)
+   An alternative to frame pointers and DWARF, ORC unwind data can be
+   used to walk the stack.  Unlike frame pointers, ORC data is out of
+   band.  So it doesn't affect runtime performance and it can be
+   reliable even when interrupts or exceptions are involved.
 
-   As an alternative to frame pointers, DWARF Call Frame Information
-   (CFI) metadata can be used to walk the stack.  Unlike frame pointers,
-   CFI metadata is out of band.  So it doesn't affect runtime
-   performance and it can be reliable even when interrupts or exceptions
-   are involved.
-
-   For C code, gcc automatically generates DWARF CFI metadata.  But for
-   asm code, generating CFI is a tedious manual approach which requires
-   manually placed .cfi assembler macros to be scattered throughout the
-   code.  It's clumsy and very easy to get wrong, and it makes the real
-   code harder to read.
-
-   Stacktool will improve this situation in several ways.  For code
-   which already has CFI annotations, it will validate them.  For code
-   which doesn't have CFI annotations, it will generate them.  So an
-   architecture can opt to strip out all the manual .cfi annotations
-   from their asm code and have objtool generate them instead.
-
-   We might also add a runtime stack validation debug option where we
-   periodically walk the stack from schedule() and/or an NMI to ensure
-   that the stack metadata is sane and that we reach the bottom of the
-   stack.
-
-   So the benefit of objtool here will be that external tooling should
-   always show perfect stack traces.  And the same will be true for
-   kernel warning/oops traces if the architecture has a runtime DWARF
-   unwinder.
+   For more details, see Documentation/x86/orc-unwinder.txt.
 
 c) Higher live patching compatibility rate
 
@@ -211,7 +189,7 @@ they mean, and suggestions for how to fix them.
    function, add proper frame pointer logic using the FRAME_BEGIN and
    FRAME_END macros.  Otherwise, if it's not a callable function, remove
    its ELF function annotation by changing ENDPROC to END, and instead
-   use the manual CFI hint macros in asm/undwarf.h.
+   use the manual unwind hint macros in asm/unwind_hints.h.
 
    If it's a GCC-compiled .c file, the error may be because the function
    uses an inline asm() statement which has a "call" instruction.  An
@@ -231,8 +209,8 @@ they mean, and suggestions for how to fix them.
    If the error is for an asm file, and the instruction is inside (or
    reachable from) a callable function, the function should be annotated
    with the ENTRY/ENDPROC macros (ENDPROC is the important one).
-   Otherwise, the code should probably be annotated with the CFI hint
-   macros in asm/undwarf.h so objtool and the unwinder can know the
+   Otherwise, the code should probably be annotated with the unwind hint
+   macros in asm/unwind_hints.h so objtool and the unwinder can know the
    stack state associated with the code.
 
    If you're 100% sure the code won't affect stack traces, or if you're
@@ -258,7 +236,7 @@ they mean, and suggestions for how to fix them.
    instructions aren't allowed in a callable function, and are most
    likely part of the kernel entry code.  They should usually not have
    the callable function annotation (ENDPROC) and should always be
-   annotated with the CFI hint macros in asm/undwarf.h.
+   annotated with the unwind hint macros in asm/unwind_hints.h.
 
 
 6. file.o: warning: objtool: func()+0x26: sibling call from callable instruction with modified stack frame
@@ -272,7 +250,7 @@ they mean, and suggestions for how to fix them.
 
    If the instruction is not actually in a callable function (e.g.
    kernel entry code), change ENDPROC to END and annotate manually with
-   the CFI hint macros in asm/undwarf.h.
+   the unwind hint macros in asm/unwind_hints.h.
 
 
 7. file: warning: objtool: func()+0x5c: stack state mismatch
@@ -288,8 +266,8 @@ they mean, and suggestions for how to fix them.
 
    Another possibility is that the code has some asm or inline asm which
    does some unusual things to the stack or the frame pointer.  In such
-   cases it's probably appropriate to use the CFI hint macros in
-   asm/undwarf.h.
+   cases it's probably appropriate to use the unwind hint macros in
+   asm/unwind_hints.h.
 
 
 8. file.o: warning: objtool: funcA() falls through to next function funcB()

tools/objtool/Makefile

@@ -52,6 +52,9 @@ $(OBJTOOL): $(LIBSUBCMD) $(OBJTOOL_IN)
 	diff -I'^#include' arch/x86/insn/inat.h ../../arch/x86/include/asm/inat.h >/dev/null && \
 	diff -I'^#include' arch/x86/insn/inat_types.h ../../arch/x86/include/asm/inat_types.h >/dev/null) \
 	|| echo "warning: objtool: x86 instruction decoder differs from kernel" >&2 )) || true
+	@(test -d ../../kernel -a -d ../../tools -a -d ../objtool && (( \
+	diff ../../arch/x86/include/asm/orc_types.h orc_types.h >/dev/null) \
+	|| echo "warning: objtool: orc_types.h differs from kernel" >&2 )) || true
 	$(QUIET_LINK)$(CC) $(OBJTOOL_IN) $(LDFLAGS) -o $@