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Message-ID: <tip-3f5159a9221f19b08275b0a6388ab14392ae4eec@git.kernel.org> Date: Wed, 22 Apr 2015 07:11:44 -0700 From: tip-bot for Denys Vlasenko <tipbot@...or.com> To: linux-tip-commits@...r.kernel.org Cc: luto@...capital.net, wad@...omium.org, linux-kernel@...r.kernel.org, oleg@...hat.com, dvlasenk@...hat.com, ast@...mgrid.com, tglx@...utronix.de, mingo@...nel.org, keescook@...omium.org, torvalds@...ux-foundation.org, rostedt@...dmis.org, hpa@...or.com, bp@...en8.de, fweisbec@...il.com Subject: [tip:x86/asm] x86/asm/entry/32: Update -ENOSYS handling to match the 64-bit logic Commit-ID: 3f5159a9221f19b08275b0a6388ab14392ae4eec Gitweb: http://git.kernel.org/tip/3f5159a9221f19b08275b0a6388ab14392ae4eec Author: Denys Vlasenko <dvlasenk@...hat.com> AuthorDate: Tue, 21 Apr 2015 18:03:14 +0200 Committer: Ingo Molnar <mingo@...nel.org> CommitDate: Wed, 22 Apr 2015 08:41:44 +0200 x86/asm/entry/32: Update -ENOSYS handling to match the 64-bit logic Recently Andy changed the 64-bit syscall logic so that pt_regs->ax is initially set to -ENOSYS, and on syscall exit, it is updated with the actual return value. This simplified the logic there. This patch does the same for 32-bit syscall entry points. The check for %rax being too big is moved to be just before the call instruction which dispatches execution through the syscall table. There is no way to accidentally skip this check now by jumping to a label after it. This allows us to remove redundant checks after ptrace et al. If %rax is too big, we just skip over the (call, write %rax to pt_regs->ax) instruction pair. pt_regs->ax remains set to -ENOSYS, and it gets returned to userspace. Similar to 64-bit code, this eliminates the "ia32_badsys" code path. Run-tested. Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com> Cc: Alexei Starovoitov <ast@...mgrid.com> Cc: Andy Lutomirski <luto@...capital.net> Cc: Borislav Petkov <bp@...en8.de> Cc: Frederic Weisbecker <fweisbec@...il.com> Cc: H. Peter Anvin <hpa@...or.com> Cc: Kees Cook <keescook@...omium.org> Cc: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Oleg Nesterov <oleg@...hat.com> Cc: Steven Rostedt <rostedt@...dmis.org> Cc: Will Drewry <wad@...omium.org> Link: http://lkml.kernel.org/r/1429632194-13445-2-git-send-email-dvlasenk@redhat.com [ Changelog massage. ] Signed-off-by: Ingo Molnar <mingo@...nel.org> --- arch/x86/ia32/ia32entry.S | 42 ++++++++++++++---------------------------- 1 file changed, 14 insertions(+), 28 deletions(-) diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S index 3cdb9ea..56fd6dd 100644 --- a/arch/x86/ia32/ia32entry.S +++ b/arch/x86/ia32/ia32entry.S @@ -136,7 +136,7 @@ ENTRY(ia32_sysenter_target) pushq_cfi_reg rsi /* pt_regs->si */ pushq_cfi_reg rdx /* pt_regs->dx */ pushq_cfi_reg rcx /* pt_regs->cx */ - pushq_cfi_reg rax /* pt_regs->ax */ + pushq_cfi $-ENOSYS /* pt_regs->ax */ cld sub $(10*8),%rsp /* pt_regs->r8-11,bp,bx,r12-15 not saved */ CFI_ADJUST_CFA_OFFSET 10*8 @@ -163,8 +163,6 @@ sysenter_flags_fixed: testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) CFI_REMEMBER_STATE jnz sysenter_tracesys - cmpq $(IA32_NR_syscalls-1),%rax - ja ia32_badsys sysenter_do_call: /* 32bit syscall -> 64bit C ABI argument conversion */ movl %edi,%r8d /* arg5 */ @@ -173,8 +171,11 @@ sysenter_do_call: 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) @@ -241,9 +242,7 @@ sysexit_from_sys_call: movl %ebx,%esi /* 2nd arg: 1st syscall arg */ movl %eax,%edi /* 1st arg: syscall number */ call __audit_syscall_entry - movl RAX(%rsp),%eax /* reload syscall number */ - cmpq $(IA32_NR_syscalls-1),%rax - ja ia32_badsys + movl ORIG_RAX(%rsp),%eax /* reload syscall number */ movl %ebx,%edi /* reload 1st syscall arg */ movl RCX(%rsp),%esi /* reload 2nd syscall arg */ movl RDX(%rsp),%edx /* reload 3rd syscall arg */ @@ -294,13 +293,10 @@ sysenter_tracesys: #endif SAVE_EXTRA_REGS CLEAR_RREGS - movq $-ENOSYS,RAX(%rsp)/* ptrace can change this for a bad syscall */ movq %rsp,%rdi /* &pt_regs -> arg1 */ call syscall_trace_enter LOAD_ARGS32 /* reload args from stack in case ptrace changed it */ RESTORE_EXTRA_REGS - cmpq $(IA32_NR_syscalls-1),%rax - ja int_ret_from_sys_call /* sysenter_tracesys has set RAX(%rsp) */ jmp sysenter_do_call CFI_ENDPROC ENDPROC(ia32_sysenter_target) @@ -370,7 +366,7 @@ ENTRY(ia32_cstar_target) pushq_cfi_reg rdx /* pt_regs->dx */ pushq_cfi_reg rbp /* pt_regs->cx */ movl %ebp,%ecx - pushq_cfi_reg rax /* pt_regs->ax */ + pushq_cfi $-ENOSYS /* pt_regs->ax */ sub $(10*8),%rsp /* pt_regs->r8-11,bp,bx,r12-15 not saved */ CFI_ADJUST_CFA_OFFSET 10*8 @@ -386,8 +382,6 @@ ENTRY(ia32_cstar_target) testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) CFI_REMEMBER_STATE jnz cstar_tracesys - cmpq $IA32_NR_syscalls-1,%rax - ja ia32_badsys cstar_do_call: /* 32bit syscall -> 64bit C ABI argument conversion */ movl %edi,%r8d /* arg5 */ @@ -396,8 +390,11 @@ cstar_do_call: 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) @@ -444,14 +441,11 @@ cstar_tracesys: xchgl %r9d,%ebp SAVE_EXTRA_REGS CLEAR_RREGS r9 - movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */ movq %rsp,%rdi /* &pt_regs -> arg1 */ call syscall_trace_enter LOAD_ARGS32 1 /* reload args from stack in case ptrace changed it */ RESTORE_EXTRA_REGS xchgl %ebp,%r9d - cmpq $(IA32_NR_syscalls-1),%rax - ja int_ret_from_sys_call /* cstar_tracesys has set RAX(%rsp) */ jmp cstar_do_call END(ia32_cstar_target) @@ -510,7 +504,7 @@ ENTRY(ia32_syscall) pushq_cfi_reg rsi /* pt_regs->si */ pushq_cfi_reg rdx /* pt_regs->dx */ pushq_cfi_reg rcx /* pt_regs->cx */ - pushq_cfi_reg rax /* pt_regs->ax */ + pushq_cfi $-ENOSYS /* pt_regs->ax */ cld sub $(10*8),%rsp /* pt_regs->r8-11,bp,bx,r12-15 not saved */ CFI_ADJUST_CFA_OFFSET 10*8 @@ -518,8 +512,6 @@ ENTRY(ia32_syscall) 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 ia32_tracesys - cmpq $(IA32_NR_syscalls-1),%rax - ja ia32_badsys ia32_do_call: /* 32bit syscall -> 64bit C ABI argument conversion */ movl %edi,%r8d /* arg5 */ @@ -527,9 +519,12 @@ ia32_do_call: xchg %ecx,%esi /* rsi:arg2, rcx:arg4 */ movl %ebx,%edi /* arg1 */ movl %edx,%edx /* arg3 (zero extension) */ + cmpq $(IA32_NR_syscalls-1),%rax + ja 1f call *ia32_sys_call_table(,%rax,8) # xxx: rip relative ia32_sysret: movq %rax,RAX(%rsp) +1: ia32_ret_from_sys_call: CLEAR_RREGS jmp int_ret_from_sys_call @@ -537,23 +532,14 @@ ia32_ret_from_sys_call: ia32_tracesys: SAVE_EXTRA_REGS CLEAR_RREGS - movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */ movq %rsp,%rdi /* &pt_regs -> arg1 */ call syscall_trace_enter LOAD_ARGS32 /* reload args from stack in case ptrace changed it */ RESTORE_EXTRA_REGS - cmpq $(IA32_NR_syscalls-1),%rax - ja int_ret_from_sys_call /* ia32_tracesys has set RAX(%rsp) */ jmp ia32_do_call + CFI_ENDPROC END(ia32_syscall) -ia32_badsys: - movq $0,ORIG_RAX(%rsp) - movq $-ENOSYS,%rax - jmp ia32_sysret - - CFI_ENDPROC - .macro PTREGSCALL label, func ALIGN GLOBAL(\label) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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