[PATCH v4 19/57] x86/entry/head/32: use local labels

From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>, "H . Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	Andy Lutomirski <luto@amacapital.net>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Brian Gerst <brgerst@gmail.com>,
	Kees Cook <keescook@chromium.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Byungchul Park <byungchul.park@lge.com>,
	Nilay Vaish <nilayvaish@gmail.com>
Subject: [PATCH v4 19/57] x86/entry/head/32: use local labels
Date: Thu, 18 Aug 2016 08:05:59 -0500	[thread overview]
Message-ID: <24385bd04819b54ec74dfd93ec93ba92349ea793.1471525031.git.jpoimboe@redhat.com> (raw)
In-Reply-To: <cover.1471525031.git.jpoimboe@redhat.com>

Add the local label prefix to all non-function named labels in head_32.S
and entry_32.S.  In addition to decluttering the symbol table, it also
causes stack traces to be more sensible.  For example, the last reported
function in the idle task stack trace is now startup_32_smp() instead of
is486().

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 arch/x86/entry/entry_32.S | 57 ++++++++++++++++++++++++-----------------------
 arch/x86/kernel/head_32.S | 32 +++++++++++++-------------
 2 files changed, 45 insertions(+), 44 deletions(-)

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 52b77ac..aed9b11 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -65,7 +65,7 @@
 # define preempt_stop(clobbers)	DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF
 #else
 # define preempt_stop(clobbers)
-# define resume_kernel		restore_all
+# define resume_kernel		.Lrestore_all
 #endif
 
 .macro TRACE_IRQS_IRET
@@ -229,7 +229,7 @@ ENTRY(ret_from_fork)
 	/* When we fork, we trace the syscall return in the child, too. */
 	movl    %esp, %eax
 	call    syscall_return_slowpath
-	jmp     restore_all
+	jmp     .Lrestore_all
 END(ret_from_fork)
 
 ENTRY(ret_from_kernel_thread)
@@ -246,7 +246,7 @@ ENTRY(ret_from_kernel_thread)
 	 */
 	movl    %esp, %eax
 	call    syscall_return_slowpath
-	jmp     restore_all
+	jmp     .Lrestore_all
 ENDPROC(ret_from_kernel_thread)
 
 /*
@@ -280,19 +280,19 @@ ENTRY(resume_userspace)
 	TRACE_IRQS_OFF
 	movl	%esp, %eax
 	call	prepare_exit_to_usermode
-	jmp	restore_all
+	jmp	.Lrestore_all
 END(ret_from_exception)
 
 #ifdef CONFIG_PREEMPT
 ENTRY(resume_kernel)
 	DISABLE_INTERRUPTS(CLBR_ANY)
-need_resched:
+.Lneed_resched:
 	cmpl	$0, PER_CPU_VAR(__preempt_count)
-	jnz	restore_all
+	jnz	.Lrestore_all
 	testl	$X86_EFLAGS_IF, PT_EFLAGS(%esp)	# interrupts off (exception path) ?
-	jz	restore_all
+	jz	.Lrestore_all
 	call	preempt_schedule_irq
-	jmp	need_resched
+	jmp	.Lneed_resched
 END(resume_kernel)
 #endif
 
@@ -313,7 +313,7 @@ GLOBAL(__begin_SYSENTER_singlestep_region)
  */
 ENTRY(xen_sysenter_target)
 	addl	$5*4, %esp			/* remove xen-provided frame */
-	jmp	sysenter_past_esp
+	jmp	.Lsysenter_past_esp
 #endif
 
 /*
@@ -350,7 +350,7 @@ ENTRY(xen_sysenter_target)
  */
 ENTRY(entry_SYSENTER_32)
 	movl	TSS_sysenter_sp0(%esp), %esp
-sysenter_past_esp:
+.Lsysenter_past_esp:
 	pushl	$__USER_DS		/* pt_regs->ss */
 	pushl	%ebp			/* pt_regs->sp (stashed in bp) */
 	pushfl				/* pt_regs->flags (except IF = 0) */
@@ -481,11 +481,11 @@ ENTRY(entry_INT80_32)
 	call	do_int80_syscall_32
 .Lsyscall_32_done:
 
-restore_all:
+.Lrestore_all:
 	TRACE_IRQS_IRET
-restore_all_notrace:
+.Lrestore_all_notrace:
 #ifdef CONFIG_X86_ESPFIX32
-	ALTERNATIVE	"jmp restore_nocheck", "", X86_BUG_ESPFIX
+	ALTERNATIVE	"jmp .Lrestore_nocheck", "", X86_BUG_ESPFIX
 
 	movl	PT_EFLAGS(%esp), %eax		# mix EFLAGS, SS and CS
 	/*
@@ -497,22 +497,23 @@ restore_all_notrace:
 	movb	PT_CS(%esp), %al
 	andl	$(X86_EFLAGS_VM | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax
 	cmpl	$((SEGMENT_LDT << 8) | USER_RPL), %eax
-	je ldt_ss				# returning to user-space with LDT SS
+	je .Lldt_ss				# returning to user-space with LDT SS
 #endif
-restore_nocheck:
+.Lrestore_nocheck:
 	RESTORE_REGS 4				# skip orig_eax/error_code
-irq_return:
+.Lirq_return:
 	INTERRUPT_RETURN
+
 .section .fixup, "ax"
 ENTRY(iret_exc	)
 	pushl	$0				# no error code
 	pushl	$do_iret_error
 	jmp	error_code
 .previous
-	_ASM_EXTABLE(irq_return, iret_exc)
+	_ASM_EXTABLE(.Lirq_return, iret_exc)
 
 #ifdef CONFIG_X86_ESPFIX32
-ldt_ss:
+.Lldt_ss:
 /*
  * Setup and switch to ESPFIX stack
  *
@@ -541,7 +542,7 @@ ldt_ss:
 	 */
 	DISABLE_INTERRUPTS(CLBR_EAX)
 	lss	(%esp), %esp			/* switch to espfix segment */
-	jmp	restore_nocheck
+	jmp	.Lrestore_nocheck
 #endif
 ENDPROC(entry_INT80_32)
 
@@ -861,7 +862,7 @@ ftrace_call:
 	popl	%edx
 	popl	%ecx
 	popl	%eax
-ftrace_ret:
+.Lftrace_ret:
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 .globl ftrace_graph_call
 ftrace_graph_call:
@@ -931,7 +932,7 @@ GLOBAL(ftrace_regs_call)
 	popl	%gs
 	addl	$8, %esp			/* Skip orig_ax and ip */
 	popf					/* Pop flags at end (no addl to corrupt flags) */
-	jmp	ftrace_ret
+	jmp	.Lftrace_ret
 
 	popf
 	jmp	ftrace_stub
@@ -942,7 +943,7 @@ ENTRY(mcount)
 	jb	ftrace_stub			/* Paging not enabled yet? */
 
 	cmpl	$ftrace_stub, ftrace_trace_function
-	jnz	trace
+	jnz	.Ltrace
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	cmpl	$ftrace_stub, ftrace_graph_return
 	jnz	ftrace_graph_caller
@@ -955,7 +956,7 @@ ftrace_stub:
 	ret
 
 	/* taken from glibc */
-trace:
+.Ltrace:
 	pushl	%eax
 	pushl	%ecx
 	pushl	%edx
@@ -1094,7 +1095,7 @@ ENTRY(nmi)
 	movl	%ss, %eax
 	cmpw	$__ESPFIX_SS, %ax
 	popl	%eax
-	je	nmi_espfix_stack
+	je	.Lnmi_espfix_stack
 #endif
 
 	pushl	%eax				# pt_regs->orig_ax
@@ -1110,7 +1111,7 @@ ENTRY(nmi)
 
 	/* Not on SYSENTER stack. */
 	call	do_nmi
-	jmp	restore_all_notrace
+	jmp	.Lrestore_all_notrace
 
 .Lnmi_from_sysenter_stack:
 	/*
@@ -1121,10 +1122,10 @@ ENTRY(nmi)
 	movl	PER_CPU_VAR(cpu_current_top_of_stack), %esp
 	call	do_nmi
 	movl	%ebp, %esp
-	jmp	restore_all_notrace
+	jmp	.Lrestore_all_notrace
 
 #ifdef CONFIG_X86_ESPFIX32
-nmi_espfix_stack:
+.Lnmi_espfix_stack:
 	/*
 	 * create the pointer to lss back
 	 */
@@ -1142,7 +1143,7 @@ nmi_espfix_stack:
 	call	do_nmi
 	RESTORE_REGS
 	lss	12+4(%esp), %esp		# back to espfix stack
-	jmp	irq_return
+	jmp	.Lirq_return
 #endif
 END(nmi)
 
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index b9ceb44..d87bec4 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -249,19 +249,19 @@ page_pde_offset = (__PAGE_OFFSET >> 20);
 #ifdef CONFIG_PARAVIRT
 	/* This is can only trip for a broken bootloader... */
 	cmpw $0x207, pa(boot_params + BP_version)
-	jb default_entry
+	jb .Ldefault_entry
 
 	/* Paravirt-compatible boot parameters.  Look to see what architecture
 		we're booting under. */
 	movl pa(boot_params + BP_hardware_subarch), %eax
 	cmpl $num_subarch_entries, %eax
-	jae bad_subarch
+	jae .Lbad_subarch
 
 	movl pa(subarch_entries)(,%eax,4), %eax
 	subl $__PAGE_OFFSET, %eax
 	jmp *%eax
 
-bad_subarch:
+.Lbad_subarch:
 WEAK(lguest_entry)
 WEAK(xen_entry)
 	/* Unknown implementation; there's really
@@ -271,14 +271,14 @@ WEAK(xen_entry)
 	__INITDATA
 
 subarch_entries:
-	.long default_entry		/* normal x86/PC */
+	.long .Ldefault_entry		/* normal x86/PC */
 	.long lguest_entry		/* lguest hypervisor */
 	.long xen_entry			/* Xen hypervisor */
-	.long default_entry		/* Moorestown MID */
+	.long .Ldefault_entry		/* Moorestown MID */
 num_subarch_entries = (. - subarch_entries) / 4
 .previous
 #else
-	jmp default_entry
+	jmp .Ldefault_entry
 #endif /* CONFIG_PARAVIRT */
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -319,7 +319,7 @@ ENTRY(startup_32_smp)
 	call load_ucode_ap
 #endif
 
-default_entry:
+.Ldefault_entry:
 #define CR0_STATE	(X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \
 			 X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \
 			 X86_CR0_PG)
@@ -349,7 +349,7 @@ default_entry:
 	pushfl
 	popl %eax			# get EFLAGS
 	testl $X86_EFLAGS_ID,%eax	# did EFLAGS.ID remained set?
-	jz enable_paging		# hw disallowed setting of ID bit
+	jz .Lenable_paging		# hw disallowed setting of ID bit
 					# which means no CPUID and no CR4
 
 	xorl %eax,%eax
@@ -359,13 +359,13 @@ default_entry:
 	movl $1,%eax
 	cpuid
 	andl $~1,%edx			# Ignore CPUID.FPU
-	jz enable_paging		# No flags or only CPUID.FPU = no CR4
+	jz .Lenable_paging		# No flags or only CPUID.FPU = no CR4
 
 	movl pa(mmu_cr4_features),%eax
 	movl %eax,%cr4
 
 	testb $X86_CR4_PAE, %al		# check if PAE is enabled
-	jz enable_paging
+	jz .Lenable_paging
 
 	/* Check if extended functions are implemented */
 	movl $0x80000000, %eax
@@ -373,7 +373,7 @@ default_entry:
 	/* Value must be in the range 0x80000001 to 0x8000ffff */
 	subl $0x80000001, %eax
 	cmpl $(0x8000ffff-0x80000001), %eax
-	ja enable_paging
+	ja .Lenable_paging
 
 	/* Clear bogus XD_DISABLE bits */
 	call verify_cpu
@@ -382,7 +382,7 @@ default_entry:
 	cpuid
 	/* Execute Disable bit supported? */
 	btl $(X86_FEATURE_NX & 31), %edx
-	jnc enable_paging
+	jnc .Lenable_paging
 
 	/* Setup EFER (Extended Feature Enable Register) */
 	movl $MSR_EFER, %ecx
@@ -392,7 +392,7 @@ default_entry:
 	/* Make changes effective */
 	wrmsr
 
-enable_paging:
+.Lenable_paging:
 
 /*
  * Enable paging
@@ -421,7 +421,7 @@ enable_paging:
  */
 	movb $4,X86			# at least 486
 	cmpl $-1,X86_CPUID
-	je is486
+	je .Lis486
 
 	/* get vendor info */
 	xorl %eax,%eax			# call CPUID with 0 -> return vendor ID
@@ -432,7 +432,7 @@ enable_paging:
 	movl %ecx,X86_VENDOR_ID+8	# last 4 chars
 
 	orl %eax,%eax			# do we have processor info as well?
-	je is486
+	je .Lis486
 
 	movl $1,%eax		# Use the CPUID instruction to get CPU type
 	cpuid
@@ -446,7 +446,7 @@ enable_paging:
 	movb %cl,X86_MASK
 	movl %edx,X86_CAPABILITY
 
-is486:
+.Lis486:
 	movl $0x50022,%ecx	# set AM, WP, NE and MP
 	movl %cr0,%eax
 	andl $0x80000011,%eax	# Save PG,PE,ET
-- 
2.7.4
