Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1240086
| From | Andy Lutomirski <luto@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH v2 16/36] x86/entry/64/compat: Remove most of the fast system call machinery |
| Date | 2015-10-06 03:00 +0200 |
| Message-ID | <qgoLO-7cw-47@gated-at.bofh.it> (permalink) |
| References | <qgoC6-715-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
We now have only one code path that calls through the compat syscall table. This will make it much more pleasant to change the pt_regs vs register calling convention, which we need to do to move the call into C. Signed-off-by: Andy Lutomirski <luto@kernel.org> --- arch/x86/entry/entry_64_compat.S | 246 +-------------------------------------- 1 file changed, 4 insertions(+), 242 deletions(-) diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S index 8f847722ce72..3216e6072312 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -101,119 +101,13 @@ sysenter_flags_fixed: movl $11, %edi call do_exit - /* - * Re-enable interrupts. IRQ tracing already thinks that IRQs are - * on (since we treat user mode as having IRQs on), and the - * prologue above is too short for it to be worth adding a - * tracing round trip. - */ - ENABLE_INTERRUPTS(CLBR_NONE) - - /* - * no need to do an access_ok check here because rbp has been - * 32-bit zero extended - */ - ASM_STAC -1: movl (%rbp), %ebp - _ASM_EXTABLE(1b, ia32_badarg) - ASM_CLAC - - orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS) - testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) - jnz sysenter_tracesys - -sysenter_do_call: - /* 32-bit syscall -> 64-bit C ABI argument conversion */ - movl %edi, %r8d /* arg5 */ - movl %ebp, %r9d /* arg6 */ - xchg %ecx, %esi /* rsi:arg2, rcx:arg4 */ - movl %ebx, %edi /* arg1 */ - movl %edx, %edx /* arg3 (zero extension) */ -sysenter_dispatch: - cmpq $(IA32_NR_syscalls-1), %rax - ja 1f - call *ia32_sys_call_table(, %rax, 8) - movq %rax, RAX(%rsp) -1: - DISABLE_INTERRUPTS(CLBR_NONE) - TRACE_IRQS_OFF - testl $_TIF_ALLWORK_MASK, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) - jnz ia32_ret_from_sys_call_irqs_off -sysexit_from_sys_call: - /* - * NB: SYSEXIT is not obviously safe for 64-bit kernels -- an - * NMI between STI and SYSEXIT has poorly specified behavior, - * and and NMI followed by an IRQ with usergs is fatal. So - * we just pretend we're using SYSEXIT but we really use - * SYSRETL instead. - * - * This code path is still called 'sysexit' because it pairs - * with 'sysenter' and it uses the SYSENTER calling convention. - */ - andl $~TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS) - movl RIP(%rsp), %ecx /* User %eip */ - movq RAX(%rsp), %rax - movl RSI(%rsp), %esi - movl RDI(%rsp), %edi - xorl %edx, %edx /* Do not leak kernel information */ - xorq %r8, %r8 - xorq %r9, %r9 - xorq %r10, %r10 - movl EFLAGS(%rsp), %r11d /* User eflags */ - TRACE_IRQS_ON - - /* - * SYSRETL works even on Intel CPUs. Use it in preference to SYSEXIT, - * since it avoids a dicey window with interrupts enabled. - */ - movl RSP(%rsp), %esp - - /* - * USERGS_SYSRET32 does: - * gsbase = user's gs base - * eip = ecx - * rflags = r11 - * cs = __USER32_CS - * ss = __USER_DS - * - * The prologue set RIP(%rsp) to VDSO32_SYSENTER_RETURN, which does: - * - * pop %ebp - * pop %edx - * pop %ecx - * - * Therefore, we invoke SYSRETL with EDX and R8-R10 zeroed to - * avoid info leaks. R11 ends up with VDSO32_SYSENTER_RETURN's - * address (already known to user code), and R12-R15 are - * callee-saved and therefore don't contain any interesting - * kernel data. - */ - USERGS_SYSRET32 + /* Unreachable. */ + ud2 sysenter_fix_flags: pushq $X86_EFLAGS_FIXED popfq jmp sysenter_flags_fixed - -sysenter_tracesys: - SAVE_EXTRA_REGS - xorl %eax, %eax /* Do not leak kernel information */ - movq %rax, R11(%rsp) - movq %rax, R10(%rsp) - movq %rax, R9(%rsp) - movq %rax, R8(%rsp) - movq %rsp, %rdi /* &pt_regs -> arg1 */ - call syscall_trace_enter - - /* Reload arg registers from stack. (see sysenter_tracesys) */ - movl RCX(%rsp), %ecx - movl RDX(%rsp), %edx - movl RSI(%rsp), %esi - movl RDI(%rsp), %edi - movl %eax, %eax /* zero extension */ - - RESTORE_EXTRA_REGS - jmp sysenter_do_call ENDPROC(entry_SYSENTER_compat) /* @@ -280,142 +174,10 @@ ENTRY(entry_SYSCALL_compat) pushq $-ENOSYS /* pt_regs->ax */ sub $(10*8), %rsp /* pt_regs->r8-11, bp, bx, r12-15 not saved */ - /* - * No need to do an access_ok check here because r8 has been - * 32-bit zero extended: - */ - ASM_STAC -1: movl (%r8), %r9d - _ASM_EXTABLE(1b, ia32_badarg) - ASM_CLAC - orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS) - testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) - jnz cstar_tracesys - -cstar_do_call: - /* 32-bit syscall -> 64-bit C ABI argument conversion */ - movl %edi, %r8d /* arg5 */ - /* r9 already loaded */ /* arg6 */ - xchg %ecx, %esi /* rsi:arg2, rcx:arg4 */ - movl %ebx, %edi /* arg1 */ - movl %edx, %edx /* arg3 (zero extension) */ - -cstar_dispatch: - cmpq $(IA32_NR_syscalls-1), %rax - ja 1f - - call *ia32_sys_call_table(, %rax, 8) - movq %rax, RAX(%rsp) -1: - DISABLE_INTERRUPTS(CLBR_NONE) - TRACE_IRQS_OFF - testl $_TIF_ALLWORK_MASK, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) - jnz ia32_ret_from_sys_call_irqs_off - -sysretl_from_sys_call: - andl $~TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS) - movl RDX(%rsp), %edx - movl RSI(%rsp), %esi - movl RDI(%rsp), %edi - movl RIP(%rsp), %ecx - movl EFLAGS(%rsp), %r11d - movq RAX(%rsp), %rax - xorq %r10, %r10 - xorq %r9, %r9 - xorq %r8, %r8 - TRACE_IRQS_ON - movl RSP(%rsp), %esp - /* - * 64-bit->32-bit SYSRET restores eip from ecx, - * eflags from r11 (but RF and VM bits are forced to 0), - * cs and ss are loaded from MSRs. - * (Note: 32-bit->32-bit SYSRET is different: since r11 - * does not exist, it merely sets eflags.IF=1). - * - * NB: On AMD CPUs with the X86_BUG_SYSRET_SS_ATTRS bug, the ss - * descriptor is not reinitialized. This means that we must - * avoid SYSRET with SS == NULL, which could happen if we schedule, - * exit the kernel, and re-enter using an interrupt vector. (All - * interrupt entries on x86_64 set SS to NULL.) We prevent that - * from happening by reloading SS in __switch_to. - */ - USERGS_SYSRET32 - -cstar_tracesys: - xchgl %r9d, %ebp - SAVE_EXTRA_REGS - xorl %eax, %eax /* Do not leak kernel information */ - movq %rax, R11(%rsp) - movq %rax, R10(%rsp) - movq %r9, R9(%rsp) - movq %rax, R8(%rsp) - movq %rsp, %rdi /* &pt_regs -> arg1 */ - call syscall_trace_enter - movl R9(%rsp), %r9d - - /* Reload arg registers from stack. (see sysenter_tracesys) */ - movl RCX(%rsp), %ecx - movl RDX(%rsp), %edx - movl RSI(%rsp), %esi - movl RDI(%rsp), %edi - movl %eax, %eax /* zero extension */ - - RESTORE_EXTRA_REGS - xchgl %ebp, %r9d - jmp cstar_do_call + /* Unreachable. */ + ud2 END(entry_SYSCALL_compat) -ia32_badarg: - /* - * So far, we've entered kernel mode, set AC, turned on IRQs, and - * saved C regs except r8-r11. We haven't done any of the other - * standard entry work, though. We want to bail, but we shouldn't - * treat this as a syscall entry since we don't even know what the - * args are. Instead, treat this as a non-syscall entry, finish - * the entry work, and immediately exit after setting AX = -EFAULT. - * - * We're really just being polite here. Killing the task outright - * would be a reasonable action, too. Given that the only valid - * way to have gotten here is through the vDSO, and we already know - * that the stack pointer is bad, the task isn't going to survive - * for long no matter what we do. - */ - - ASM_CLAC /* undo STAC */ - movq $-EFAULT, RAX(%rsp) /* return -EFAULT if possible */ - - /* Fill in the rest of pt_regs */ - xorl %eax, %eax - movq %rax, R11(%rsp) - movq %rax, R10(%rsp) - movq %rax, R9(%rsp) - movq %rax, R8(%rsp) - SAVE_EXTRA_REGS - - /* Turn IRQs back off. */ - DISABLE_INTERRUPTS(CLBR_NONE) - TRACE_IRQS_OFF - - /* Now finish entering normal kernel mode. */ -#ifdef CONFIG_CONTEXT_TRACKING - call enter_from_user_mode -#endif - - /* And exit again. */ - jmp retint_user - -ia32_ret_from_sys_call_irqs_off: - TRACE_IRQS_ON - ENABLE_INTERRUPTS(CLBR_NONE) - -ia32_ret_from_sys_call: - xorl %eax, %eax /* Do not leak kernel information */ - movq %rax, R11(%rsp) - movq %rax, R10(%rsp) - movq %rax, R9(%rsp) - movq %rax, R8(%rsp) - jmp int_ret_from_sys_call - /* * Emulated IA32 system calls via int 0x80. * -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
[PATCH v2 04/36] selftests/x86: Add a test for syscall restart and arg modification Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
[tip:x86/asm] selftests/x86: Add a test for ptrace syscall restart and arg modification tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-07 18:20 +0200
[PATCH v2 20/36] x86/entry: Add do_syscall_32, a C function to do 32-bit syscalls Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
[tip:x86/asm] x86/entry: Add do_syscall_32(), a C function to do 32-bit syscalls tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:20 +0200
[PATCH v2 13/36] x86/vdso/32: Save extra registers in the INT80 vsyscall path Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
[tip:x86/asm] x86/vdso/32: Save extra registers in the INT80 vsyscall path tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:10 +0200
[PATCH v2 11/36] x86/vdso: Replace hex int80 CFI annotations with gas directives Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
[tip:x86/asm] x86/vdso: Replace hex int80 CFI annotations with GAS directives tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:10 +0200
[PATCH v2 02/36] x86/uaccess: __chk_range_not_ok is unlikely to return true Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
Re: [PATCH v2 02/36] x86/uaccess: __chk_range_not_ok is unlikely to return true Borislav Petkov <bp@alien8.de> - 2015-10-07 13:00 +0200
Re: [PATCH v2 02/36] x86/uaccess: __chk_range_not_ok is unlikely to return true Ingo Molnar <mingo@kernel.org> - 2015-10-07 18:30 +0200
[tip:x86/asm] x86/uaccess: Add unlikely() to __chk_range_not_ok() failure paths tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-07 18:20 +0200
[PATCH v2 06/36] x86/entry: Move lockdep_sys_exit to prepare_exit_to_usermode Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
[tip:x86/asm] x86/entry, locking/lockdep: Move lockdep_sys_exit() to prepare_exit_to_usermode() tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-07 18:20 +0200
Re: [tip:x86/asm] x86/entry, locking/lockdep: Move lockdep_sys_exit() to prepare_exit_to_usermode() Peter Zijlstra <peterz@infradead.org> - 2015-10-08 11:00 +0200
Re: [tip:x86/asm] x86/entry, locking/lockdep: Move lockdep_sys_exit() to prepare_exit_to_usermode() Andy Lutomirski <luto@amacapital.net> - 2015-10-09 21:40 +0200
[PATCH v2 16/36] x86/entry/64/compat: Remove most of the fast system call machinery Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
[tip:x86/asm] x86/entry/64/compat: Remove most of the fast system call machinery tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:20 +0200
[PATCH v2 22/36] x86/entry: Add C code for fast system call entries Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
Re: [PATCH v2 22/36] x86/entry: Add C code for fast system call entries Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-06 10:30 +0200
Re: [PATCH v2 22/36] x86/entry: Add C code for fast system call entries Andy Lutomirski <luto@amacapital.net> - 2015-10-06 20:30 +0200
Re: [PATCH v2 22/36] x86/entry: Add C code for fast system call entries Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-06 10:30 +0200
[tip:x86/asm] x86/entry: Add C code for fast system call entries tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:20 +0200
[PATCH v2 30/36] x86/entry: Make irqs_disabled checks in exit code depend on lockdep Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
[tip:x86/asm] x86/entry: Make irqs_disabled checks in exit code depend on lockdep tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:20 +0200
[PATCH v2 15/36] x86/entry/64/compat: Remove audit optimizations Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
[tip:x86/asm] x86/entry/64/compat: Remove audit optimizations tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:20 +0200
[PATCH v2 32/36] x86/entry: Micro-optimize compat fast syscall arg fetch Andy Lutomirski <luto@kernel.org> - 2015-10-06 03:00 +0200
Re: [PATCH v2 32/36] x86/entry: Micro-optimize compat fast syscall arg fetch Ingo Molnar <mingo@kernel.org> - 2015-10-09 09:40 +0200
Re: [PATCH v2 32/36] x86/entry: Micro-optimize compat fast syscall arg fetch Andy Lutomirski <luto@amacapital.net> - 2015-10-09 21:30 +0200
Re: [PATCH v2 32/36] x86/entry: Micro-optimize compat fast syscall arg fetch Ingo Molnar <mingo@kernel.org> - 2015-10-10 11:10 +0200
[tip:x86/asm] x86/entry: Micro-optimize compat fast syscall arg fetch tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2015-10-09 15:20 +0200
Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-06 10:40 +0200
Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Ingo Molnar <mingo@kernel.org> - 2015-10-06 11:00 +0200
Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Andy Lutomirski <luto@amacapital.net> - 2015-10-06 20:30 +0200
Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Ingo Molnar <mingo@kernel.org> - 2015-10-09 15:10 +0200
Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Richard Weinberger <richard.weinberger@gmail.com> - 2015-10-12 20:40 +0200
Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Andy Lutomirski <luto@amacapital.net> - 2015-10-12 20:50 +0200
Re: [PATCH v2 00/36] x86: Rewrite all syscall entries except native 64-bit Richard Weinberger <richard@nod.at> - 2015-10-12 23:10 +0200
csiph-web