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[174.84.153.250]) by smtp.gmail.com with ESMTPSA id i28sm31475599qtc.57.2020.03.13.12.52.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Mar 2020 12:52:30 -0700 (PDT) From: Brian Gerst To: linux-kernel@vger.kernel.org, x86@kernel.org Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , Andy Lutomirski , Dominik Brodowski , Brian Gerst Subject: [PATCH v4 16/18] x86-32: Enable pt_regs based syscalls Date: Fri, 13 Mar 2020 15:51:42 -0400 Message-Id: <20200313195144.164260-17-brgerst@gmail.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200313195144.164260-1-brgerst@gmail.com> References: <20200313195144.164260-1-brgerst@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Enable pt_regs based syscalls for 32-bit. This makes the 32-bit native kernel consistent with the 64-bit kernel, and improves the syscall interface by not needing to push all 6 potential arguments onto the stack. Signed-off-by: Brian Gerst Reviewed-by: Dominik Brodowski --- arch/x86/Kconfig | 2 +- arch/x86/entry/common.c | 15 ---- arch/x86/entry/syscall_32.c | 15 +--- arch/x86/include/asm/syscall.h | 6 -- arch/x86/include/asm/syscall_wrapper.h | 111 ++++++++++++++----------- arch/x86/include/asm/syscalls.h | 29 ------- 6 files changed, 64 insertions(+), 114 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 532f52b99094..b65f07a06549 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -30,7 +30,6 @@ config X86_64 select MODULES_USE_ELF_RELA select NEED_DMA_MAP_STATE select SWIOTLB - select ARCH_HAS_SYSCALL_WRAPPER config FORCE_DYNAMIC_FTRACE def_bool y @@ -79,6 +78,7 @@ config X86 select ARCH_HAS_STRICT_KERNEL_RWX select ARCH_HAS_STRICT_MODULE_RWX select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE + select ARCH_HAS_SYSCALL_WRAPPER select ARCH_HAS_UBSAN_SANITIZE_ALL select ARCH_HAVE_NMI_SAFE_CMPXCHG select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index c3a8e6513f74..76735ec813e6 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -334,20 +334,7 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs) if (likely(nr < IA32_NR_syscalls)) { nr = array_index_nospec(nr, IA32_NR_syscalls); -#ifdef CONFIG_IA32_EMULATION regs->ax = ia32_sys_call_table[nr](regs); -#else - /* - * It's possible that a 32-bit syscall implementation - * takes a 64-bit parameter but nonetheless assumes that - * the high bits are zero. Make sure we zero-extend all - * of the args. - */ - regs->ax = ia32_sys_call_table[nr]( - (unsigned int)regs->bx, (unsigned int)regs->cx, - (unsigned int)regs->dx, (unsigned int)regs->si, - (unsigned int)regs->di, (unsigned int)regs->bp); -#endif /* CONFIG_IA32_EMULATION */ } syscall_return_slowpath(regs); @@ -440,9 +427,7 @@ __visible long do_fast_syscall_32(struct pt_regs *regs) } #endif -#ifdef CONFIG_X86_64 SYSCALL_DEFINE0(ni_syscall) { return -ENOSYS; } -#endif diff --git a/arch/x86/entry/syscall_32.c b/arch/x86/entry/syscall_32.c index 41ec9c66fe15..097413c705ad 100644 --- a/arch/x86/entry/syscall_32.c +++ b/arch/x86/entry/syscall_32.c @@ -4,33 +4,22 @@ #include #include #include +#include #include #include -#ifdef CONFIG_IA32_EMULATION -/* On X86_64, we use struct pt_regs * to pass parameters to syscalls */ #define __SYSCALL_I386(nr, sym) extern asmlinkage long __ia32_##sym(const struct pt_regs *); -#define __sys_ni_syscall __ia32_sys_ni_syscall -#else /* CONFIG_IA32_EMULATION */ -#define __SYSCALL_I386(nr, sym) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); -extern asmlinkage long sys_ni_syscall(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); -#define __sys_ni_syscall sys_ni_syscall -#endif /* CONFIG_IA32_EMULATION */ #include #undef __SYSCALL_I386 -#ifdef CONFIG_IA32_EMULATION #define __SYSCALL_I386(nr, sym) [nr] = __ia32_##sym, -#else /* CONFIG_IA32_EMULATION */ -#define __SYSCALL_I386(nr, sym) [nr] = sym, -#endif /* CONFIG_IA32_EMULATION */ __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] = &__sys_ni_syscall, + [0 ... __NR_ia32_syscall_max] = &__ia32_sys_ni_syscall, #include }; diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h index f4d010d0fa30..bb427d8cb1ef 100644 --- a/arch/x86/include/asm/syscall.h +++ b/arch/x86/include/asm/syscall.h @@ -16,13 +16,7 @@ #include /* for TS_COMPAT */ #include -#ifdef CONFIG_X86_64 typedef asmlinkage long (*sys_call_ptr_t)(const struct pt_regs *); -#else -typedef asmlinkage long (*sys_call_ptr_t)(unsigned long, unsigned long, - unsigned long, unsigned long, - unsigned long, unsigned long); -#endif /* CONFIG_X86_64 */ extern const sys_call_ptr_t sys_call_table[]; #if defined(CONFIG_X86_32) diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h index 0f126e40a464..5e13e2caf2e4 100644 --- a/arch/x86/include/asm/syscall_wrapper.h +++ b/arch/x86/include/asm/syscall_wrapper.h @@ -11,6 +11,47 @@ struct pt_regs; extern asmlinkage long __x64_sys_ni_syscall(const struct pt_regs *regs); extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs); +/* + * Instead of the generic __SYSCALL_DEFINEx() definition, the x86 version takes + * struct pt_regs *regs as the only argument of the syscall stub(s) named as: + * __x64_sys_*() - 64-bit native syscall + * __ia32_sys_*() - 32-bit native syscall or common compat syscall + * __ia32_compat_sys_*() - 32-bit compat syscall + * __x32_compat_sys_*() - 64-bit X32 compat syscall + * + * The registers are decoded according to the ABI: + * 64-bit: RDI, RSI, RDX, R10, R8, R9 + * 32-bit: EBX, ECX, EDX, ESI, EDI, EBP + * + * The stub then passes the decoded arguments to the __se_sys_*() wrapper to + * perform sign-extension (omitted for zero-argument syscalls). Finally the + * arguments are passed to the __do_sys_*() function which is the actual + * syscall. These wrappers are marked as inline so the compiler can optimize + * the functions where appropriate. + * + * Example assembly (slightly re-ordered for better readability): + * + * <__x64_sys_recv>: <-- syscall with 4 parameters + * callq <__fentry__> + * + * mov 0x70(%rdi),%rdi <-- decode regs->di + * mov 0x68(%rdi),%rsi <-- decode regs->si + * mov 0x60(%rdi),%rdx <-- decode regs->dx + * mov 0x38(%rdi),%rcx <-- decode regs->r10 + * + * xor %r9d,%r9d <-- clear %r9 + * xor %r8d,%r8d <-- clear %r8 + * + * callq __sys_recvfrom <-- do the actual work in __sys_recvfrom() + * which takes 6 arguments + * + * cltq <-- extend return value to 64-bit + * retq <-- return + * + * This approach avoids leaking random user-provided register content down + * the call chain. + */ + /* Mapping of registers to parameters for syscalls on x86-64 and x32 */ #define SC_X86_64_REGS_TO_ARGS(x, ...) \ __MAP(x,__SC_ARGS \ @@ -68,6 +109,26 @@ extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs); #define __X64_SYS_NI(name) #endif /* CONFIG_X86_64 */ +#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) +#define __IA32_SYS_STUB0(name) \ + __SYS_STUB0(ia32, sys_##name) + +#define __IA32_SYS_STUBx(x, name, ...) \ + __SYS_STUBx(ia32, sys##name, \ + SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__)) + +#define __IA32_COND_SYSCALL(name) \ + __COND_SYSCALL(ia32, sys_##name) + +#define __IA32_SYS_NI(name) \ + __SYS_NI(ia32, sys_##name) +#else /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */ +#define __IA32_SYS_STUB0(name) +#define __IA32_SYS_STUBx(x, name, ...) +#define __IA32_COND_SYSCALL(name) +#define __IA32_SYS_NI(name) +#endif /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */ + #ifdef CONFIG_IA32_EMULATION /* * For IA32 emulation, we need to handle "compat" syscalls *and* create @@ -90,27 +151,11 @@ extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs); #define __IA32_COMPAT_SYS_NI(name) \ __SYS_NI(ia32, compat_sys_##name) -#define __IA32_SYS_STUB0(name) \ - __SYS_STUB0(ia32, sys_##name) - -#define __IA32_SYS_STUBx(x, name, ...) \ - __SYS_STUBx(ia32, sys##name, \ - SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__)) - -#define __IA32_COND_SYSCALL(name) \ - __COND_SYSCALL(ia32, sys_##name) - -#define __IA32_SYS_NI(name) \ - __SYS_NI(ia32, sys_##name) #else /* CONFIG_IA32_EMULATION */ #define __IA32_COMPAT_SYS_STUB0(name) #define __IA32_COMPAT_SYS_STUBx(x, name, ...) #define __IA32_COMPAT_COND_SYSCALL(name) #define __IA32_COMPAT_SYS_NI(name) -#define __IA32_SYS_STUB0(name) -#define __IA32_SYS_STUBx(x, name, ...) -#define __IA32_COND_SYSCALL(name) -#define __IA32_SYS_NI(name) #endif /* CONFIG_IA32_EMULATION */ @@ -180,40 +225,6 @@ extern asmlinkage long __ia32_sys_ni_syscall(const struct pt_regs *regs); #endif /* CONFIG_COMPAT */ - -/* - * Instead of the generic __SYSCALL_DEFINEx() definition, this macro takes - * struct pt_regs *regs as the only argument of the syscall stub named - * __x64_sys_*(). It decodes just the registers it needs and passes them on to - * the __se_sys_*() wrapper performing sign extension and then to the - * __do_sys_*() function doing the actual job. These wrappers and functions - * are inlined (at least in very most cases), meaning that the assembly looks - * as follows (slightly re-ordered for better readability): - * - * <__x64_sys_recv>: <-- syscall with 4 parameters - * callq <__fentry__> - * - * mov 0x70(%rdi),%rdi <-- decode regs->di - * mov 0x68(%rdi),%rsi <-- decode regs->si - * mov 0x60(%rdi),%rdx <-- decode regs->dx - * mov 0x38(%rdi),%rcx <-- decode regs->r10 - * - * xor %r9d,%r9d <-- clear %r9 - * xor %r8d,%r8d <-- clear %r8 - * - * callq __sys_recvfrom <-- do the actual work in __sys_recvfrom() - * which takes 6 arguments - * - * cltq <-- extend return value to 64-bit - * retq <-- return - * - * This approach avoids leaking random user-provided register content down - * the call chain. - * - * If IA32_EMULATION is enabled, this macro generates an additional wrapper - * named __ia32_sys_*() which decodes the struct pt_regs *regs according - * to the i386 calling convention (bx, cx, dx, si, di, bp). - */ #define __SYSCALL_DEFINEx(x, name, ...) \ static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\ diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h index 91b7b6e1a115..06cbdca634d6 100644 --- a/arch/x86/include/asm/syscalls.h +++ b/arch/x86/include/asm/syscalls.h @@ -17,33 +17,4 @@ /* kernel/ioport.c */ long ksys_ioperm(unsigned long from, unsigned long num, int turn_on); -#ifdef CONFIG_X86_32 -/* - * These definitions are only valid on pure 32-bit systems; x86-64 uses a - * different syscall calling convention - */ -asmlinkage long sys_ioperm(unsigned long, unsigned long, int); -asmlinkage long sys_iopl(unsigned int); - -/* kernel/ldt.c */ -asmlinkage long sys_modify_ldt(int, void __user *, unsigned long); - -/* kernel/signal.c */ -asmlinkage long sys_rt_sigreturn(void); - -/* kernel/tls.c */ -asmlinkage long sys_set_thread_area(struct user_desc __user *); -asmlinkage long sys_get_thread_area(struct user_desc __user *); - -/* X86_32 only */ - -/* kernel/signal.c */ -asmlinkage long sys_sigreturn(void); - -/* kernel/vm86_32.c */ -struct vm86_struct; -asmlinkage long sys_vm86old(struct vm86_struct __user *); -asmlinkage long sys_vm86(unsigned long, unsigned long); - -#endif /* CONFIG_X86_32 */ #endif /* _ASM_X86_SYSCALLS_H */ -- 2.24.1