[PATCH v3 18/51] x86/entry/head/32: use local labels

From: Josh Poimboeuf
Date: Fri Aug 12 2016 - 10:32:06 EST

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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@xxxxxxxxxx>
---
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 0b56666..df4e045 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -64,7 +64,7 @@
# 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
@@ -212,7 +212,7 @@ 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)
@@ -230,7 +230,7 @@ ENTRY(ret_from_kernel_thread)
*/
movl %esp, %eax
call syscall_return_slowpath
- jmp restore_all
+ jmp .Lrestore_all
ENDPROC(ret_from_kernel_thread)

/*
@@ -264,19 +264,19 @@ 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

@@ -297,7 +297,7 @@ 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

/*
@@ -334,7 +334,7 @@ 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) */
@@ -465,11 +465,11 @@ 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
/*
@@ -481,22 +481,23 @@ 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
*
@@ -525,7 +526,7 @@ ldt_ss:
*/
DISABLE_INTERRUPTS(CLBR_EAX)
lss (%esp), %esp /* switch to espfix segment */
- jmp restore_nocheck
+ jmp .Lrestore_nocheck
#endif
ENDPROC(entry_INT80_32)

@@ -845,7 +846,7 @@ ftrace_call:
popl %edx
popl %ecx
popl %eax
-ftrace_ret:
+.Lftrace_ret:
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.globl ftrace_graph_call
ftrace_graph_call:
@@ -915,7 +916,7 @@ 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
@@ -926,7 +927,7 @@ 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
@@ -939,7 +940,7 @@ ftrace_stub:
ret

/* taken from glibc */
-trace:
+.Ltrace:
pushl %eax
pushl %ecx
pushl %edx
@@ -1078,7 +1079,7 @@ 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
@@ -1094,7 +1095,7 @@ ENTRY(nmi)

/* Not on SYSENTER stack. */
call do_nmi
- jmp restore_all_notrace
+ jmp .Lrestore_all_notrace

.Lnmi_from_sysenter_stack:
/*
@@ -1105,10 +1106,10 @@ 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
*/
@@ -1126,7 +1127,7 @@ 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 6fc4f1d..53202d7 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
@@ -318,7 +318,7 @@ 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)
@@ -348,7 +348,7 @@ 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
@@ -358,13 +358,13 @@ 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
@@ -372,7 +372,7 @@ 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
@@ -381,7 +381,7 @@ 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
@@ -391,7 +391,7 @@ default_entry:
/* Make changes effective */
wrmsr

-enable_paging:
+.Lenable_paging:

/*
* Enable paging
@@ -420,7 +420,7 @@ 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
@@ -431,7 +431,7 @@ 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
@@ -445,7 +445,7 @@ 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

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