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Message-Id: <f95b7f7dfaacf88a8cae85bb06226cae53769287.1444091584.git.luto@kernel.org> Date: Mon, 5 Oct 2015 17:48:05 -0700 From: Andy Lutomirski <luto@...nel.org> To: x86@...nel.org, linux-kernel@...r.kernel.org Cc: Brian Gerst <brgerst@...il.com>, Denys Vlasenko <dvlasenk@...hat.com>, Linus Torvalds <torvalds@...ux-foundation.org>, Borislav Petkov <bp@...en8.de>, Andy Lutomirski <luto@...nel.org> Subject: [PATCH v2 17/36] x86/entry/64/compat: Set up full pt_regs for all compat syscalls This is conceptually simpler. More importantly, it eliminates the PTREGSCALL and execve stubs, which were not compatible with the C ABI. This means that C code can call through the compat syscall table. The execve stubs are a bit subtle. They did two things: they cleared some registers and they forced slow-path return. Neither is necessary any more: elf_common_init clears the extra registers and start_thread calls force_iret(). Signed-off-by: Andy Lutomirski <luto@...nel.org> --- arch/x86/entry/entry_64.S | 6 +---- arch/x86/entry/entry_64_compat.S | 42 +++++++++++----------------------- arch/x86/entry/syscalls/syscall_32.tbl | 12 +++++----- 3 files changed, 20 insertions(+), 40 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 766254c2068b..4f8c25eb3437 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -391,20 +391,16 @@ GLOBAL(stub_execveat) jmp return_from_execve END(stub_execveat) -#if defined(CONFIG_X86_X32_ABI) || defined(CONFIG_IA32_EMULATION) +#if defined(CONFIG_X86_X32_ABI) .align 8 GLOBAL(stub_x32_execve) -GLOBAL(stub32_execve) call compat_sys_execve jmp return_from_execve -END(stub32_execve) END(stub_x32_execve) .align 8 GLOBAL(stub_x32_execveat) -GLOBAL(stub32_execveat) call compat_sys_execveat jmp return_from_execve -END(stub32_execveat) END(stub_x32_execveat) #endif diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S index 3216e6072312..2c2aac577b3c 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -219,12 +219,18 @@ ENTRY(entry_INT80_compat) pushq %rdx /* pt_regs->dx */ pushq %rcx /* pt_regs->cx */ pushq $-ENOSYS /* pt_regs->ax */ - pushq $0 /* pt_regs->r8 */ - pushq $0 /* pt_regs->r9 */ - pushq $0 /* pt_regs->r10 */ - pushq $0 /* pt_regs->r11 */ + xorq %r8,%r8 + pushq %r8 /* pt_regs->r8 = 0 */ + pushq %r8 /* pt_regs->r9 = 0 */ + pushq %r8 /* pt_regs->r10 = 0 */ + pushq %r8 /* pt_regs->r11 = 0 */ + pushq %rbx /* pt_regs->rbx */ + pushq %rbp /* pt_regs->rbp */ + pushq %r12 /* pt_regs->r12 */ + pushq %r13 /* pt_regs->r13 */ + pushq %r14 /* pt_regs->r14 */ + pushq %r15 /* pt_regs->r15 */ cld - sub $(6*8), %rsp /* pt_regs->bp, bx, r12-15 not saved */ orl $TS_COMPAT, ASM_THREAD_INFO(TI_status, %rsp, SIZEOF_PTREGS) testl $_TIF_WORK_SYSCALL_ENTRY, ASM_THREAD_INFO(TI_flags, %rsp, SIZEOF_PTREGS) @@ -243,10 +249,10 @@ ia32_do_call: call *ia32_sys_call_table(, %rax, 8) movq %rax, RAX(%rsp) 1: + RESTORE_EXTRA_REGS jmp int_ret_from_sys_call ia32_tracesys: - SAVE_EXTRA_REGS movq %rsp, %rdi /* &pt_regs -> arg1 */ call syscall_trace_enter /* @@ -261,25 +267,11 @@ ia32_tracesys: movl RSI(%rsp), %esi movl RDI(%rsp), %edi movl %eax, %eax /* zero extension */ - RESTORE_EXTRA_REGS jmp ia32_do_call END(entry_INT80_compat) - .macro PTREGSCALL label, func - ALIGN -GLOBAL(\label) - leaq \func(%rip), %rax - jmp ia32_ptregs_common - .endm - - PTREGSCALL stub32_rt_sigreturn, sys32_rt_sigreturn - PTREGSCALL stub32_sigreturn, sys32_sigreturn - PTREGSCALL stub32_fork, sys_fork - PTREGSCALL stub32_vfork, sys_vfork - ALIGN GLOBAL(stub32_clone) - leaq sys_clone(%rip), %rax /* * The 32-bit clone ABI is: clone(..., int tls_val, int *child_tidptr). * The 64-bit clone ABI is: clone(..., int *child_tidptr, int tls_val). @@ -288,12 +280,4 @@ GLOBAL(stub32_clone) * so we need to swap arguments here before calling it: */ xchg %r8, %rcx - jmp ia32_ptregs_common - - ALIGN -ia32_ptregs_common: - SAVE_EXTRA_REGS 8 - call *%rax - RESTORE_EXTRA_REGS 8 - ret -END(ia32_ptregs_common) + jmp sys_clone diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl index 7663c455b9f6..caa2c712d1e7 100644 --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -8,7 +8,7 @@ # 0 i386 restart_syscall sys_restart_syscall 1 i386 exit sys_exit -2 i386 fork sys_fork stub32_fork +2 i386 fork sys_fork sys_fork 3 i386 read sys_read 4 i386 write sys_write 5 i386 open sys_open compat_sys_open @@ -17,7 +17,7 @@ 8 i386 creat sys_creat 9 i386 link sys_link 10 i386 unlink sys_unlink -11 i386 execve sys_execve stub32_execve +11 i386 execve sys_execve compat_sys_execve 12 i386 chdir sys_chdir 13 i386 time sys_time compat_sys_time 14 i386 mknod sys_mknod @@ -125,7 +125,7 @@ 116 i386 sysinfo sys_sysinfo compat_sys_sysinfo 117 i386 ipc sys_ipc compat_sys_ipc 118 i386 fsync sys_fsync -119 i386 sigreturn sys_sigreturn stub32_sigreturn +119 i386 sigreturn sys_sigreturn sys32_sigreturn 120 i386 clone sys_clone stub32_clone 121 i386 setdomainname sys_setdomainname 122 i386 uname sys_newuname @@ -179,7 +179,7 @@ 170 i386 setresgid sys_setresgid16 171 i386 getresgid sys_getresgid16 172 i386 prctl sys_prctl -173 i386 rt_sigreturn sys_rt_sigreturn stub32_rt_sigreturn +173 i386 rt_sigreturn sys_rt_sigreturn sys32_rt_sigreturn 174 i386 rt_sigaction sys_rt_sigaction compat_sys_rt_sigaction 175 i386 rt_sigprocmask sys_rt_sigprocmask 176 i386 rt_sigpending sys_rt_sigpending compat_sys_rt_sigpending @@ -196,7 +196,7 @@ 187 i386 sendfile sys_sendfile compat_sys_sendfile 188 i386 getpmsg 189 i386 putpmsg -190 i386 vfork sys_vfork stub32_vfork +190 i386 vfork sys_vfork sys_vfork 191 i386 ugetrlimit sys_getrlimit compat_sys_getrlimit 192 i386 mmap2 sys_mmap_pgoff 193 i386 truncate64 sys_truncate64 sys32_truncate64 @@ -364,7 +364,7 @@ 355 i386 getrandom sys_getrandom 356 i386 memfd_create sys_memfd_create 357 i386 bpf sys_bpf -358 i386 execveat sys_execveat stub32_execveat +358 i386 execveat sys_execveat compat_sys_execveat 359 i386 socket sys_socket 360 i386 socketpair sys_socketpair 361 i386 bind sys_bind -- 2.4.3 -- 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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