Commit 1dfb0f47 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86-entry-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 entry code related updates from Thomas Gleixner:

 - Consolidate the macros for .byte ... opcode sequences

 - Deduplicate register offset defines in include files

 - Simplify the ia32,x32 compat handling of the related syscall tables
   to get rid of #ifdeffery.

 - Clear all EFLAGS which are not required for syscall handling

 - Consolidate the syscall tables and switch the generation over to the
   generic shell script and remove the CFLAGS tweaks which are not
   longer required.

 - Use 'int' type for system call numbers to match the generic code.

 - Add more selftests for syscalls

* tag 'x86-entry-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/syscalls: Don't adjust CFLAGS for syscall tables
  x86/syscalls: Remove -Wno-override-init for syscall tables
  x86/uml/syscalls: Remove array index from syscall initializers
  x86/syscalls: Clear 'offset' and 'prefix' in case they are set in env
  x86/entry: Use int everywhere for system call numbers
  x86/entry: Treat out of range and gap system calls the same
  x86/entry/64: Sign-extend system calls on entry to int
  selftests/x86/syscall: Add tests under ptrace to syscall_numbering_64
  selftests/x86/syscall: Simplify message reporting in syscall_numbering
  selftests/x86/syscall: Update and extend syscall_numbering_64
  x86/syscalls: Switch to generic syscallhdr.sh
  x86/syscalls: Use __NR_syscalls instead of __NR_syscall_max
  x86/unistd: Define X32_NR_syscalls only for 64-bit kernel
  x86/syscalls: Stop filling syscall arrays with *_sys_ni_syscall
  x86/syscalls: Switch to generic syscalltbl.sh
  x86/entry/x32: Rename __x32_compat_sys_* to __x64_compat_sys_*
parents a22c3f61 48f7eee8

arch/um/kernel/skas/syscall.c

+1 −1
Original line number Diff line number Diff line
@@ -41,7 +41,7 @@ void handle_syscall(struct uml_pt_regs *r) 
		goto out;



	syscall = UPT_SYSCALL_NR(r);

	if (syscall >= 0 && syscall <= __NR_syscall_max)

	if (syscall >= 0 && syscall < __NR_syscalls)

		PT_REGS_SET_SYSCALL_RETURN(regs,

				EXECUTE_SYSCALL(syscall, regs));

arch/x86/entry/Makefile

+0 −10
Original line number Diff line number Diff line
@@ -8,18 +8,8 @@ UBSAN_SANITIZE := n 
KCOV_INSTRUMENT := n



CFLAGS_REMOVE_common.o		= $(CC_FLAGS_FTRACE)

CFLAGS_REMOVE_syscall_64.o	= $(CC_FLAGS_FTRACE)

CFLAGS_REMOVE_syscall_32.o	= $(CC_FLAGS_FTRACE)

CFLAGS_REMOVE_syscall_x32.o	= $(CC_FLAGS_FTRACE)



CFLAGS_common.o			+= -fno-stack-protector

CFLAGS_syscall_64.o		+= -fno-stack-protector

CFLAGS_syscall_32.o		+= -fno-stack-protector

CFLAGS_syscall_x32.o		+= -fno-stack-protector



CFLAGS_syscall_64.o		+= $(call cc-option,-Wno-override-init,)

CFLAGS_syscall_32.o		+= $(call cc-option,-Wno-override-init,)

CFLAGS_syscall_x32.o		+= $(call cc-option,-Wno-override-init,)



obj-y				:= entry_$(BITS).o thunk_$(BITS).o syscall_$(BITS).o

obj-y				+= common.o

arch/x86/entry/common.c

+61 −26
Original line number Diff line number Diff line
@@ -36,61 +36,97 @@ 
#include <asm/irq_stack.h>



#ifdef CONFIG_X86_64

__visible noinstr void do_syscall_64(struct pt_regs *regs, unsigned long nr)



static __always_inline bool do_syscall_x64(struct pt_regs *regs, int nr)

{

	/*

	 * Convert negative numbers to very high and thus out of range

	 * numbers for comparisons.

	 */

	unsigned int unr = nr;



	if (likely(unr < NR_syscalls)) {

		unr = array_index_nospec(unr, NR_syscalls);

		regs->ax = sys_call_table[unr](regs);

		return true;

	}

	return false;

}



static __always_inline bool do_syscall_x32(struct pt_regs *regs, int nr)

{

	/*

	 * Adjust the starting offset of the table, and convert numbers

	 * < __X32_SYSCALL_BIT to very high and thus out of range

	 * numbers for comparisons.

	 */

	unsigned int xnr = nr - __X32_SYSCALL_BIT;



	if (IS_ENABLED(CONFIG_X86_X32_ABI) && likely(xnr < X32_NR_syscalls)) {

		xnr = array_index_nospec(xnr, X32_NR_syscalls);

		regs->ax = x32_sys_call_table[xnr](regs);

		return true;

	}

	return false;

}



__visible noinstr void do_syscall_64(struct pt_regs *regs, int nr)

{

	add_random_kstack_offset();

	nr = syscall_enter_from_user_mode(regs, nr);



	instrumentation_begin();

	if (likely(nr < NR_syscalls)) {

		nr = array_index_nospec(nr, NR_syscalls);

		regs->ax = sys_call_table[nr](regs);

#ifdef CONFIG_X86_X32_ABI

	} else if (likely((nr & __X32_SYSCALL_BIT) &&

			  (nr & ~__X32_SYSCALL_BIT) < X32_NR_syscalls)) {

		nr = array_index_nospec(nr & ~__X32_SYSCALL_BIT,

					X32_NR_syscalls);

		regs->ax = x32_sys_call_table[nr](regs);

#endif



	if (!do_syscall_x64(regs, nr) && !do_syscall_x32(regs, nr) && nr != -1) {

		/* Invalid system call, but still a system call. */

		regs->ax = __x64_sys_ni_syscall(regs);

	}



	instrumentation_end();

	syscall_exit_to_user_mode(regs);

}

#endif



#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)

static __always_inline unsigned int syscall_32_enter(struct pt_regs *regs)

static __always_inline int syscall_32_enter(struct pt_regs *regs)

{

	if (IS_ENABLED(CONFIG_IA32_EMULATION))

		current_thread_info()->status |= TS_COMPAT;



	return (unsigned int)regs->orig_ax;

	return (int)regs->orig_ax;

}



/*

 * Invoke a 32-bit syscall.  Called with IRQs on in CONTEXT_KERNEL.

 */

static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs,

						  unsigned int nr)

static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs, int nr)

{

	if (likely(nr < IA32_NR_syscalls)) {

		nr = array_index_nospec(nr, IA32_NR_syscalls);

		regs->ax = ia32_sys_call_table[nr](regs);

	/*

	 * Convert negative numbers to very high and thus out of range

	 * numbers for comparisons.

	 */

	unsigned int unr = nr;



	if (likely(unr < IA32_NR_syscalls)) {

		unr = array_index_nospec(unr, IA32_NR_syscalls);

		regs->ax = ia32_sys_call_table[unr](regs);

	} else if (nr != -1) {

		regs->ax = __ia32_sys_ni_syscall(regs);

	}

}



/* Handles int $0x80 */

__visible noinstr void do_int80_syscall_32(struct pt_regs *regs)

{

	unsigned int nr = syscall_32_enter(regs);

	int nr = syscall_32_enter(regs);



	add_random_kstack_offset();

	/*

	 * Subtlety here: if ptrace pokes something larger than 2^32-1 into

	 * orig_ax, the unsigned int return value truncates it.  This may

	 * or may not be necessary, but it matches the old asm behavior.

	 * Subtlety here: if ptrace pokes something larger than 2^31-1 into

	 * orig_ax, the int return value truncates it. This matches

	 * the semantics of syscall_get_nr().

	 */

	nr = (unsigned int)syscall_enter_from_user_mode(regs, nr);

	nr = syscall_enter_from_user_mode(regs, nr);

	instrumentation_begin();



	do_syscall_32_irqs_on(regs, nr);
@@ -101,7 +137,7 @@ __visible noinstr void do_int80_syscall_32(struct pt_regs *regs) 


static noinstr bool __do_fast_syscall_32(struct pt_regs *regs)

{

	unsigned int nr = syscall_32_enter(regs);

	int nr = syscall_32_enter(regs);

	int res;



	add_random_kstack_offset();
@@ -136,8 +172,7 @@ static noinstr bool __do_fast_syscall_32(struct pt_regs *regs) 
		return false;

	}



	/* The case truncates any ptrace induced syscall nr > 2^32 -1 */

	nr = (unsigned int)syscall_enter_from_user_mode_work(regs, nr);

	nr = syscall_enter_from_user_mode_work(regs, nr);



	/* Now this is just like a normal syscall. */

	do_syscall_32_irqs_on(regs, nr);

arch/x86/entry/entry_64.S

+2 −1
Original line number Diff line number Diff line
@@ -108,7 +108,8 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_hwframe, SYM_L_GLOBAL) 


	/* IRQs are off. */

	movq	%rsp, %rdi

	movq	%rax, %rsi

	/* Sign extend the lower 32bit as syscall numbers are treated as int */

	movslq	%eax, %rsi

	call	do_syscall_64		/* returns with IRQs disabled */



	/*

arch/x86/entry/syscall_32.c

+10 −10
Original line number Diff line number Diff line
@@ -5,21 +5,21 @@ 
#include <linux/sys.h>

#include <linux/cache.h>

#include <linux/syscalls.h>

#include <asm/unistd.h>

#include <asm/syscall.h>



#define __SYSCALL_I386(nr, sym) extern long __ia32_##sym(const struct pt_regs *);

#ifdef CONFIG_IA32_EMULATION

#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, compat)

#else

#define __SYSCALL_WITH_COMPAT(nr, native, compat)	__SYSCALL(nr, native)

#endif



#define __SYSCALL(nr, sym) extern long __ia32_##sym(const struct pt_regs *);



#include <asm/syscalls_32.h>

#undef __SYSCALL_I386

#undef __SYSCALL



#define __SYSCALL_I386(nr, sym) [nr] = __ia32_##sym,

#define __SYSCALL(nr, sym) __ia32_##sym,



__visible const sys_call_ptr_t ia32_sys_call_table[__NR_ia32_syscall_max+1] = {

	/*

	 * Smells like a compiler bug -- it doesn't work

	 * when the & below is removed.

	 */

	[0 ... __NR_ia32_syscall_max] = &__ia32_sys_ni_syscall,

__visible const sys_call_ptr_t ia32_sys_call_table[] = {

#include <asm/syscalls_32.h>

};