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Fri, 28 Feb 2020 14:58:09 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 01SEsLgP186603; Fri, 28 Feb 2020 14:58:09 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3030.oracle.com with ESMTP id 2ydcs8pg42-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 28 Feb 2020 14:58:09 +0000 Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 01SEw1AT026881; Fri, 28 Feb 2020 14:58:01 GMT Received: from [10.39.209.75] (/10.39.209.75) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 28 Feb 2020 06:58:01 -0800 Subject: Re: [patch 08/24] x86/entry: Convert Divide Error to IDTENTRY To: Thomas Gleixner , LKML Cc: x86@kernel.org, Steven Rostedt , Brian Gerst , Juergen Gross , Paolo Bonzini , Arnd Bergmann References: <20200225221606.511535280@linutronix.de> <20200225222648.970676604@linutronix.de> From: Alexandre Chartre Organization: Oracle Corporation Message-ID: <4afd832a-2a78-798a-97e0-d1e3636cc290@oracle.com> Date: Fri, 28 Feb 2020 15:58:03 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20200225222648.970676604@linutronix.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9545 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 bulkscore=0 malwarescore=0 mlxlogscore=999 mlxscore=0 phishscore=0 suspectscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002280118 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9544 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 malwarescore=0 bulkscore=0 lowpriorityscore=0 mlxlogscore=999 phishscore=0 spamscore=0 adultscore=0 suspectscore=0 impostorscore=0 clxscore=1015 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002280117 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/25/20 11:16 PM, Thomas Gleixner wrote: > Convert #DE to IDTENTRY: > - Implement the C entry point with DEFINE_IDTENTRY > - Emit the ASM stub with DECLARE_IDTENTRY > - Remove the ASM idtentry in 64bit > - Remove the open coded ASM entry code in 32bit > - Fixup the XEN/PV code > > No functional change. > > Signed-off-by: Thomas Gleixner > --- > arch/x86/entry/entry_32.S | 7 ------- > arch/x86/entry/entry_64.S | 1 - > arch/x86/include/asm/idtentry.h | 3 +++ > arch/x86/include/asm/traps.h | 3 --- > arch/x86/kernel/idt.c | 2 +- > arch/x86/kernel/traps.c | 7 ++++++- > arch/x86/xen/enlighten_pv.c | 7 ++++++- > arch/x86/xen/xen-asm_64.S | 2 +- > 8 files changed, 17 insertions(+), 15 deletions(-) > > --- a/arch/x86/entry/entry_32.S > +++ b/arch/x86/entry/entry_32.S > @@ -1386,13 +1386,6 @@ SYM_CODE_START(alignment_check) > jmp common_exception > SYM_CODE_END(alignment_check) > > -SYM_CODE_START(divide_error) > - ASM_CLAC > - pushl $0 # no error code > - pushl $do_divide_error > - jmp common_exception > -SYM_CODE_END(divide_error) > - > #ifdef CONFIG_X86_MCE > SYM_CODE_START(machine_check) > ASM_CLAC > --- a/arch/x86/entry/entry_64.S > +++ b/arch/x86/entry/entry_64.S > @@ -1061,7 +1061,6 @@ apicinterrupt IRQ_WORK_VECTOR irq_work > * Exception entry points. > */ > > -idtentry X86_TRAP_DE divide_error do_divide_error has_error_code=0 > idtentry X86_TRAP_OF overflow do_overflow has_error_code=0 > idtentry X86_TRAP_BP int3 do_int3 has_error_code=0 > idtentry X86_TRAP_BR bounds do_bounds has_error_code=0 > --- a/arch/x86/include/asm/idtentry.h > +++ b/arch/x86/include/asm/idtentry.h > @@ -76,4 +76,7 @@ static __always_inline void __##func(str > > #endif /* __ASSEMBLY__ */ > > +/* Simple exception entries: */ > +DECLARE_IDTENTRY(X86_TRAP_DE, exc_divide_error); > + I think this macro has a tricky behavior because it will declare C functions when included in a C file, and define assembly idtentry when included in an assembly file. I see your point which is to have a single statement which provides both C and assembly functions, but this dual behavior is not obvious when reading the code. Maybe add a comment to explain this behavior? Reviewed-by: Alexandre Chartre alex. > #endif > --- a/arch/x86/include/asm/traps.h > +++ b/arch/x86/include/asm/traps.h > @@ -11,7 +11,6 @@ > > #define dotraplinkage __visible > > -asmlinkage void divide_error(void); > asmlinkage void debug(void); > asmlinkage void nmi(void); > asmlinkage void int3(void); > @@ -38,7 +37,6 @@ asmlinkage void machine_check(void); > asmlinkage void simd_coprocessor_error(void); > > #if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV) > -asmlinkage void xen_divide_error(void); > asmlinkage void xen_xennmi(void); > asmlinkage void xen_xendebug(void); > asmlinkage void xen_int3(void); > @@ -62,7 +60,6 @@ asmlinkage void xen_machine_check(void); > asmlinkage void xen_simd_coprocessor_error(void); > #endif > > -dotraplinkage void do_divide_error(struct pt_regs *regs, long error_code); > dotraplinkage void do_debug(struct pt_regs *regs, long error_code); > dotraplinkage void do_nmi(struct pt_regs *regs, long error_code); > dotraplinkage void do_int3(struct pt_regs *regs, long error_code); > --- a/arch/x86/kernel/idt.c > +++ b/arch/x86/kernel/idt.c > @@ -70,7 +70,7 @@ static const __initconst struct idt_data > * set up TSS. > */ > static const __initconst struct idt_data def_idts[] = { > - INTG(X86_TRAP_DE, divide_error), > + INTG(X86_TRAP_DE, asm_exc_divide_error), > INTG(X86_TRAP_NMI, nmi), > INTG(X86_TRAP_BR, bounds), > INTG(X86_TRAP_UD, invalid_op), > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -279,6 +279,12 @@ static inline void __user *error_get_tra > return (void __user *)uprobe_get_trap_addr(regs); > } > > +DEFINE_IDTENTRY(exc_divide_error) > +{ > + do_error_trap(regs, 0, "divide_error", X86_TRAP_DE, SIGFPE, > + FPE_INTDIV, error_get_trap_addr(regs)); > +} > + > #define IP ((void __user *)uprobe_get_trap_addr(regs)) > #define DO_ERROR(trapnr, signr, sicode, addr, str, name) \ > dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \ > @@ -286,7 +292,6 @@ dotraplinkage void do_##name(struct pt_r > do_error_trap(regs, error_code, str, trapnr, signr, sicode, addr); \ > } > > -DO_ERROR(X86_TRAP_DE, SIGFPE, FPE_INTDIV, IP, "divide error", divide_error) > DO_ERROR(X86_TRAP_OF, SIGSEGV, 0, NULL, "overflow", overflow) > DO_ERROR(X86_TRAP_UD, SIGILL, ILL_ILLOPN, IP, "invalid opcode", invalid_op) > DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, 0, NULL, "coprocessor segment overrun", coprocessor_segment_overrun) > --- a/arch/x86/xen/enlighten_pv.c > +++ b/arch/x86/xen/enlighten_pv.c > @@ -602,6 +602,11 @@ struct trap_array_entry { > bool ist_okay; > }; > > +#define TRAP_ENTRY(func, ist_ok) { \ > + .orig = asm_##func, \ > + .xen = xen_asm_##func, \ > + .ist_okay = ist_ok } > + > static struct trap_array_entry trap_array[] = { > { debug, xen_xendebug, true }, > { double_fault, xen_double_fault, true }, > @@ -615,7 +620,7 @@ static struct trap_array_entry trap_arra > { entry_INT80_compat, xen_entry_INT80_compat, false }, > #endif > { page_fault, xen_page_fault, false }, > - { divide_error, xen_divide_error, false }, > + TRAP_ENTRY(exc_divide_error, false ), > { bounds, xen_bounds, false }, > { invalid_op, xen_invalid_op, false }, > { device_not_available, xen_device_not_available, false }, > --- a/arch/x86/xen/xen-asm_64.S > +++ b/arch/x86/xen/xen-asm_64.S > @@ -28,7 +28,7 @@ SYM_CODE_END(xen_\name) > _ASM_NOKPROBE(xen_\name) > .endm > > -xen_pv_trap divide_error > +xen_pv_trap asm_exc_divide_error > xen_pv_trap debug > xen_pv_trap xendebug > xen_pv_trap int3 > >