Commit b2502b41 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

x86/asm/entry: Untangle 'system_call' into two entry points: entry_SYSCALL_64 and entry_INT80_32 



The 'system_call' entry points differ starkly between native 32-bit and 64-bit
kernels: on 32-bit kernels it defines the INT 0x80 entry point, while on
64-bit it's the SYSCALL entry point.

This is pretty confusing when looking at generic code, and it also obscures
the nature of the entry point at the assembly level.

So unangle this by splitting the name into its two uses:

	system_call (32) -> entry_INT80_32
	system_call (64) -> entry_SYSCALL_64

As per the generic naming scheme for x86 system call entry points:

	entry_MNEMONIC_qualifier

where 'qualifier' is one of _32, _64 or _compat.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 4c8cd0c5

arch/x86/entry/entry_32.S

+2 −2
Original line number Diff line number Diff line
@@ -415,7 +415,7 @@ sysexit_audit: 
ENDPROC(entry_SYSENTER_32)



	# system call handler stub

ENTRY(system_call)

ENTRY(entry_INT80_32)

	ASM_CLAC

	pushl %eax			# save orig_eax

	SAVE_ALL
@@ -508,7 +508,7 @@ ldt_ss: 
	lss (%esp), %esp		/* switch to espfix segment */

	jmp restore_nocheck

#endif

ENDPROC(system_call)

ENDPROC(entry_INT80_32)



	# perform work that needs to be done immediately before resumption

	ALIGN

arch/x86/entry/entry_64.S

+5 −5
Original line number Diff line number Diff line
@@ -137,7 +137,7 @@ ENDPROC(native_usergs_sysret64) 
 * with them due to bugs in both AMD and Intel CPUs.

 */



ENTRY(system_call)

ENTRY(entry_SYSCALL_64)

	/*

	 * Interrupts are off on entry.

	 * We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON,
@@ -149,7 +149,7 @@ ENTRY(system_call) 
	 * after the swapgs, so that it can do the swapgs

	 * for the guest and jump here on syscall.

	 */

GLOBAL(system_call_after_swapgs)

GLOBAL(entry_SYSCALL_64_after_swapgs)



	movq	%rsp,PER_CPU_VAR(rsp_scratch)

	movq	PER_CPU_VAR(cpu_current_top_of_stack),%rsp
@@ -182,7 +182,7 @@ GLOBAL(system_call_after_swapgs) 


	testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS)

	jnz tracesys

system_call_fastpath:

entry_SYSCALL_64_fastpath:

#if __SYSCALL_MASK == ~0

	cmpq $__NR_syscall_max,%rax

#else
@@ -246,7 +246,7 @@ tracesys: 
	jnz tracesys_phase2		/* if needed, run the slow path */

	RESTORE_C_REGS_EXCEPT_RAX	/* else restore clobbered regs */

	movq ORIG_RAX(%rsp), %rax

	jmp system_call_fastpath	/*      and return to the fast path */

	jmp entry_SYSCALL_64_fastpath	/*      and return to the fast path */



tracesys_phase2:

	SAVE_EXTRA_REGS
@@ -411,7 +411,7 @@ syscall_return_via_sysret: 
opportunistic_sysret_failed:

	SWAPGS

	jmp	restore_c_regs_and_iret

END(system_call)

END(entry_SYSCALL_64)





	.macro FORK_LIKE func

arch/x86/include/asm/proto.h

+3 −2
Original line number Diff line number Diff line
@@ -5,11 +5,12 @@ 


/* misc architecture specific prototypes */



void system_call(void);

void syscall_init(void);



void entry_INT80_compat(void);

void entry_SYSCALL_64(void);

void entry_SYSCALL_compat(void);

void entry_INT80_32(void);

void entry_INT80_compat(void);

void entry_SYSENTER_32(void);

void entry_SYSENTER_compat(void);

arch/x86/kernel/cpu/common.c

+1 −1
Original line number Diff line number Diff line
@@ -1204,7 +1204,7 @@ void syscall_init(void) 
	 * set CS/DS but only a 32bit target. LSTAR sets the 64bit rip.

	 */

	wrmsrl(MSR_STAR,  ((u64)__USER32_CS)<<48  | ((u64)__KERNEL_CS)<<32);

	wrmsrl(MSR_LSTAR, system_call);

	wrmsrl(MSR_LSTAR, entry_SYSCALL_64);



#ifdef CONFIG_IA32_EMULATION

	wrmsrl(MSR_CSTAR, entry_SYSCALL_compat);

arch/x86/kernel/traps.c

+2 −3
Original line number Diff line number Diff line
@@ -72,8 +72,7 @@ gate_desc debug_idt_table[NR_VECTORS] __page_aligned_bss; 
#else

#include <asm/processor-flags.h>

#include <asm/setup.h>



asmlinkage int system_call(void);

#include <asm/proto.h>

#endif



/* Must be page-aligned because the real IDT is used in a fixmap. */
@@ -997,7 +996,7 @@ void __init trap_init(void) 
#endif



#ifdef CONFIG_X86_32

	set_system_trap_gate(IA32_SYSCALL_VECTOR, &system_call);

	set_system_trap_gate(IA32_SYSCALL_VECTOR, entry_INT80_32);

	set_bit(IA32_SYSCALL_VECTOR, used_vectors);

#endif

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