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Groups > linux.kernel > #1191851
| From | Denys Vlasenko <dvlasenk@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 2/3] x86/asm/entry/32: Remove most of SYSCALL32 code, part 1 |
| Date | 2015-07-24 15:50 +0200 |
| Message-ID | <pPLwn-7ok-23@gated-at.bofh.it> (permalink) |
| References | <pPLwl-7ok-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
SYSCALL32 code is nearly identical to SYSCALL32, except for initial section. Merge them. The removal is split into two parts, to make review eaiser. This is part 1. auditsys_entry_common and auditsys_exit macros are indented one more tab without any changes. This prevents diff from becoming unreadable. They will be removed in part 2. Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> CC: Ingo Molnar <mingo@kernel.org> CC: Linus Torvalds <torvalds@linux-foundation.org> CC: Krzysztof A. Sobiecki <sobkas@gmail.com> CC: Steven Rostedt <rostedt@goodmis.org> CC: Borislav Petkov <bp@alien8.de> CC: "H. Peter Anvin" <hpa@zytor.com> CC: Andy Lutomirski <luto@amacapital.net> CC: Oleg Nesterov <oleg@redhat.com> CC: Frederic Weisbecker <fweisbec@gmail.com> CC: Alexei Starovoitov <ast@plumgrid.com> CC: Will Drewry <wad@chromium.org> CC: Kees Cook <keescook@chromium.org> CC: x86@kernel.org CC: linux-kernel@vger.kernel.org --- arch/x86/entry/entry_64_compat.S | 237 +++++++++++---------------------------- 1 file changed, 63 insertions(+), 174 deletions(-) diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S index 9f9dfa5..2d0a2f0 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -16,13 +16,7 @@ #include <linux/linkage.h> #include <linux/err.h> -/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */ -#include <linux/elf-em.h> -#define AUDIT_ARCH_I386 (EM_386|__AUDIT_ARCH_LE) -#define __AUDIT_ARCH_LE 0x40000000 - #ifndef CONFIG_AUDITSYSCALL -# define sysexit_audit ia32_ret_from_sys_call_irqs_off # define sysretl_audit ia32_ret_from_sys_call_irqs_off #endif @@ -93,188 +87,82 @@ ENTRY(entry_SYSENTER_compat) * 32-bit zero extended */ ASM_STAC -1: movl (%rbp), %ebp +1: movl (%rbp), %r9d _ASM_EXTABLE(1b, ia32_badarg) ASM_CLAC /* - * Sysenter doesn't filter flags, so we need to clear NT - * ourselves. To save a few cycles, we can check whether - * NT was set instead of doing an unconditional popfq. + * Sysenter doesn't filter flags, so we need to clear NT ourselves. */ testl $X86_EFLAGS_NT, EFLAGS(%rsp) jnz sysenter_fix_flags sysenter_flags_fixed: - - 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 sysexit_audit - -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 RSI(%rsp), %esi - movl RDI(%rsp), %edi - movl RIP(%rsp), %ecx /* User %eip */ - movl EFLAGS(%rsp), %r11d /* User eflags */ - xorl %edx, %edx /* Do not leak kernel information */ - xorq %r10, %r10 - xorq %r9, %r9 - xorq %r8, %r8 - 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 - -#ifdef CONFIG_AUDITSYSCALL - .macro auditsys_entry_common - /* - * At this point, registers hold syscall args in the 32-bit syscall ABI: - * EAX is syscall number, the 6 args are in EBX,ECX,EDX,ESI,EDI,EBP. - * - * We want to pass them to __audit_syscall_entry(), which is a 64-bit - * C function with 5 parameters, so shuffle them to match what - * the function expects: RDI,RSI,RDX,RCX,R8. - */ - movl %esi, %r8d /* arg5 (R8 ) <= 4th syscall arg (ESI) */ - xchg %ecx, %edx /* arg4 (RCX) <= 3rd syscall arg (EDX) */ - /* arg3 (RDX) <= 2nd syscall arg (ECX) */ - movl %ebx, %esi /* arg2 (RSI) <= 1st syscall arg (EBX) */ - movl %eax, %edi /* arg1 (RDI) <= syscall number (EAX) */ - call __audit_syscall_entry - - /* - * We are going to jump back to the syscall dispatch code. - * Prepare syscall args as required by the 64-bit C ABI. - * Registers clobbered by __audit_syscall_entry() are - * loaded from pt_regs on stack: - */ - movl ORIG_RAX(%rsp), %eax /* syscall number */ - movl %ebx, %edi /* arg1 */ - movl RCX(%rsp), %esi /* arg2 */ - movl RDX(%rsp), %edx /* arg3 */ - movl RSI(%rsp), %ecx /* arg4 */ - movl RDI(%rsp), %r8d /* arg5 */ - .endm - - .macro auditsys_exit exit - TRACE_IRQS_ON - ENABLE_INTERRUPTS(CLBR_NONE) - testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) - jnz ia32_ret_from_sys_call - movl %eax, %esi /* second arg, syscall return value */ - cmpl $-MAX_ERRNO, %eax /* is it an error ? */ - jbe 1f - movslq %eax, %rsi /* if error sign extend to 64 bits */ -1: setbe %al /* 1 if error, 0 if not */ - movzbl %al, %edi /* zero-extend that into %edi */ - call __audit_syscall_exit - movq RAX(%rsp), %rax /* reload syscall return value */ - movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %edi - DISABLE_INTERRUPTS(CLBR_NONE) - TRACE_IRQS_OFF - testl %edi, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) - jz \exit - 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_irqs_off - .endm - -sysenter_auditsys: - auditsys_entry_common - movl %ebp, %r9d /* reload 6th syscall arg */ - jmp sysenter_dispatch - -sysexit_audit: - auditsys_exit sysexit_from_sys_call -#endif + jmp sysenter_jumps_here sysenter_fix_flags: pushq $(X86_EFLAGS_IF|X86_EFLAGS_FIXED) popfq jmp sysenter_flags_fixed - -sysenter_tracesys: -#ifdef CONFIG_AUDITSYSCALL - testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT), ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) - jz sysenter_auditsys -#endif - 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) + + #ifdef CONFIG_AUDITSYSCALL + .macro auditsys_entry_common + /* + * At this point, registers hold syscall args in the 32-bit syscall ABI: + * EAX is syscall number, the 6 args are in EBX,ECX,EDX,ESI,EDI,EBP. + * + * We want to pass them to __audit_syscall_entry(), which is a 64-bit + * C function with 5 parameters, so shuffle them to match what + * the function expects: RDI,RSI,RDX,RCX,R8. + */ + movl %esi, %r8d /* arg5 (R8 ) <= 4th syscall arg (ESI) */ + xchg %ecx, %edx /* arg4 (RCX) <= 3rd syscall arg (EDX) */ + /* arg3 (RDX) <= 2nd syscall arg (ECX) */ + movl %ebx, %esi /* arg2 (RSI) <= 1st syscall arg (EBX) */ + movl %eax, %edi /* arg1 (RDI) <= syscall number (EAX) */ + call __audit_syscall_entry + + /* + * We are going to jump back to the syscall dispatch code. + * Prepare syscall args as required by the 64-bit C ABI. + * Registers clobbered by __audit_syscall_entry() are + * loaded from pt_regs on stack: + */ + movl ORIG_RAX(%rsp), %eax /* syscall number */ + movl %ebx, %edi /* arg1 */ + movl RCX(%rsp), %esi /* arg2 */ + movl RDX(%rsp), %edx /* arg3 */ + movl RSI(%rsp), %ecx /* arg4 */ + movl RDI(%rsp), %r8d /* arg5 */ + .endm + + .macro auditsys_exit exit + TRACE_IRQS_ON + ENABLE_INTERRUPTS(CLBR_NONE) + testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) + jnz ia32_ret_from_sys_call + movl %eax, %esi /* second arg, syscall return value */ + cmpl $-MAX_ERRNO, %eax /* is it an error ? */ + jbe 1f + movslq %eax, %rsi /* if error sign extend to 64 bits */ + 1: setbe %al /* 1 if error, 0 if not */ + movzbl %al, %edi /* zero-extend that into %edi */ + call __audit_syscall_exit + movq RAX(%rsp), %rax /* reload syscall return value */ + movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT), %edi + DISABLE_INTERRUPTS(CLBR_NONE) + TRACE_IRQS_OFF + testl %edi, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) + jz \exit + 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_irqs_off + .endm + #endif /* * 32-bit SYSCALL instruction entry. * @@ -343,6 +231,7 @@ ENTRY(entry_SYSCALL_compat) _ASM_EXTABLE(1b, ia32_badarg) ASM_CLAC +sysenter_jumps_here: 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 @@ -421,7 +310,7 @@ cstar_tracesys: call syscall_trace_enter movl R9(%rsp), %r9d - /* Reload arg registers from stack. (see sysenter_tracesys) */ + /* Reload arg registers from stack. */ movl RCX(%rsp), %ecx movl RDX(%rsp), %edx movl RSI(%rsp), %esi -- 1.8.1.4 -- 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/
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[PATCH 1/3] x86/asm/entry/32: Massage SYSENTER32 fast path to be nearly identical to SYSCALL32 Denys Vlasenko <dvlasenk@redhat.com> - 2015-07-24 15:50 +0200
[PATCH 3/3] x86/asm/entry/32: Remove most of SYSCALL32 code, part 2 Denys Vlasenko <dvlasenk@redhat.com> - 2015-07-24 15:50 +0200
[PATCH 2/3] x86/asm/entry/32: Remove most of SYSCALL32 code, part 1 Denys Vlasenko <dvlasenk@redhat.com> - 2015-07-24 15:50 +0200
Re: [PATCH 2/3] x86/asm/entry/32: Remove most of SYSCALL32 code, part 1 Denys Vlasenko <dvlasenk@redhat.com> - 2015-07-25 20:40 +0200
Re: [PATCH 2/3] x86/asm/entry/32: Remove most of SYSCALL32 code, part 1 Andy Lutomirski <luto@amacapital.net> - 2015-07-25 21:40 +0200
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