From: Paul Gortmaker <pa...@kernel.org> This reverts commit 4591766ff6552339fbaa3d3c71814faef1988c2f.
This (3/5) is a part of a fix from the v6.6.7 content. However during repeated boot testing on qemu-x86 (32 and 64) with NFS root it hangs during the verbose printk of the PCI register layout map. The v6.6.6 and the v6.6.7 with 5 reverts does not have this issue. Note that NFS root seems to be key for some reason. https://bugzilla.yoctoproject.org/show_bug.cgi?id=15463 Signed-off-by: Paul Gortmaker <pa...@kernel.org> --- arch/x86/entry/common.c | 58 +----------------------- arch/x86/entry/entry_64_compat.S | 77 ++++++++++++++++++++++++++++++++ arch/x86/include/asm/idtentry.h | 4 -- arch/x86/include/asm/proto.h | 4 ++ arch/x86/kernel/idt.c | 2 +- arch/x86/xen/enlighten_pv.c | 2 +- arch/x86/xen/xen-asm.S | 2 +- 7 files changed, 85 insertions(+), 64 deletions(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 0f22a037be66..4cec38985414 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -119,62 +119,7 @@ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs, int nr) } } -#ifdef CONFIG_IA32_EMULATION -/** - * int80_emulation - 32-bit legacy syscall entry - * - * This entry point can be used by 32-bit and 64-bit programs to perform - * 32-bit system calls. Instances of INT $0x80 can be found inline in - * various programs and libraries. It is also used by the vDSO's - * __kernel_vsyscall fallback for hardware that doesn't support a faster - * entry method. Restarted 32-bit system calls also fall back to INT - * $0x80 regardless of what instruction was originally used to do the - * system call. - * - * This is considered a slow path. It is not used by most libc - * implementations on modern hardware except during process startup. - * - * The arguments for the INT $0x80 based syscall are on stack in the - * pt_regs structure: - * eax: system call number - * ebx, ecx, edx, esi, edi, ebp: arg1 - arg 6 - */ -DEFINE_IDTENTRY_RAW(int80_emulation) -{ - int nr; - - /* Establish kernel context. */ - enter_from_user_mode(regs); - - instrumentation_begin(); - add_random_kstack_offset(); - - /* - * The low level idtentry code pushed -1 into regs::orig_ax - * and regs::ax contains the syscall number. - * - * User tracing code (ptrace or signal handlers) might assume - * that the regs::orig_ax contains a 32-bit number on invoking - * a 32-bit syscall. - * - * Establish the syscall convention by saving the 32bit truncated - * syscall number in regs::orig_ax and by invalidating regs::ax. - */ - regs->orig_ax = regs->ax & GENMASK(31, 0); - regs->ax = -ENOSYS; - - nr = syscall_32_enter(regs); - - local_irq_enable(); - nr = syscall_enter_from_user_mode_work(regs, nr); - do_syscall_32_irqs_on(regs, nr); - - instrumentation_end(); - syscall_exit_to_user_mode(regs); -} -#else /* CONFIG_IA32_EMULATION */ - -/* Handles int $0x80 on a 32bit kernel */ +/* Handles int $0x80 */ __visible noinstr void do_int80_syscall_32(struct pt_regs *regs) { int nr = syscall_32_enter(regs); @@ -193,7 +138,6 @@ __visible noinstr void do_int80_syscall_32(struct pt_regs *regs) instrumentation_end(); syscall_exit_to_user_mode(regs); } -#endif /* !CONFIG_IA32_EMULATION */ static noinstr bool __do_fast_syscall_32(struct pt_regs *regs) { diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S index 306181e4fcb9..245697eb8485 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -277,3 +277,80 @@ SYM_INNER_LABEL(entry_SYSRETL_compat_end, SYM_L_GLOBAL) ANNOTATE_NOENDBR int3 SYM_CODE_END(entry_SYSCALL_compat) + +/* + * 32-bit legacy system call entry. + * + * 32-bit x86 Linux system calls traditionally used the INT $0x80 + * instruction. INT $0x80 lands here. + * + * This entry point can be used by 32-bit and 64-bit programs to perform + * 32-bit system calls. Instances of INT $0x80 can be found inline in + * various programs and libraries. It is also used by the vDSO's + * __kernel_vsyscall fallback for hardware that doesn't support a faster + * entry method. Restarted 32-bit system calls also fall back to INT + * $0x80 regardless of what instruction was originally used to do the + * system call. + * + * This is considered a slow path. It is not used by most libc + * implementations on modern hardware except during process startup. + * + * Arguments: + * eax system call number + * ebx arg1 + * ecx arg2 + * edx arg3 + * esi arg4 + * edi arg5 + * ebp arg6 + */ +SYM_CODE_START(entry_INT80_compat) + UNWIND_HINT_ENTRY + ENDBR + /* + * Interrupts are off on entry. + */ + ASM_CLAC /* Do this early to minimize exposure */ + ALTERNATIVE "swapgs", "", X86_FEATURE_XENPV + + /* + * User tracing code (ptrace or signal handlers) might assume that + * the saved RAX contains a 32-bit number when we're invoking a 32-bit + * syscall. Just in case the high bits are nonzero, zero-extend + * the syscall number. (This could almost certainly be deleted + * with no ill effects.) + */ + movl %eax, %eax + + /* switch to thread stack expects orig_ax and rdi to be pushed */ + pushq %rax /* pt_regs->orig_ax */ + + /* Need to switch before accessing the thread stack. */ + SWITCH_TO_KERNEL_CR3 scratch_reg=%rax + + /* In the Xen PV case we already run on the thread stack. */ + ALTERNATIVE "", "jmp .Lint80_keep_stack", X86_FEATURE_XENPV + + movq %rsp, %rax + movq PER_CPU_VAR(pcpu_hot + X86_top_of_stack), %rsp + + pushq 5*8(%rax) /* regs->ss */ + pushq 4*8(%rax) /* regs->rsp */ + pushq 3*8(%rax) /* regs->eflags */ + pushq 2*8(%rax) /* regs->cs */ + pushq 1*8(%rax) /* regs->ip */ + pushq 0*8(%rax) /* regs->orig_ax */ +.Lint80_keep_stack: + + PUSH_AND_CLEAR_REGS rax=$-ENOSYS + UNWIND_HINT_REGS + + cld + + IBRS_ENTER + UNTRAIN_RET + + movq %rsp, %rdi + call do_int80_syscall_32 + jmp swapgs_restore_regs_and_return_to_usermode +SYM_CODE_END(entry_INT80_compat) diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index 13639e57e1f8..05fd175cec7d 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -569,10 +569,6 @@ DECLARE_IDTENTRY_RAW(X86_TRAP_UD, exc_invalid_op); DECLARE_IDTENTRY_RAW(X86_TRAP_BP, exc_int3); DECLARE_IDTENTRY_RAW_ERRORCODE(X86_TRAP_PF, exc_page_fault); -#if defined(CONFIG_IA32_EMULATION) -DECLARE_IDTENTRY_RAW(IA32_SYSCALL_VECTOR, int80_emulation); -#endif - #ifdef CONFIG_X86_MCE #ifdef CONFIG_X86_64 DECLARE_IDTENTRY_MCE(X86_TRAP_MC, exc_machine_check); diff --git a/arch/x86/include/asm/proto.h b/arch/x86/include/asm/proto.h index 84294b66b916..12ef86b19910 100644 --- a/arch/x86/include/asm/proto.h +++ b/arch/x86/include/asm/proto.h @@ -32,6 +32,10 @@ void entry_SYSCALL_compat(void); void entry_SYSCALL_compat_safe_stack(void); void entry_SYSRETL_compat_unsafe_stack(void); void entry_SYSRETL_compat_end(void); +void entry_INT80_compat(void); +#ifdef CONFIG_XEN_PV +void xen_entry_INT80_compat(void); +#endif #endif void x86_configure_nx(void); diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c index fc77a96040b7..b786d48f5a0f 100644 --- a/arch/x86/kernel/idt.c +++ b/arch/x86/kernel/idt.c @@ -117,7 +117,7 @@ static const __initconst struct idt_data def_idts[] = { SYSG(X86_TRAP_OF, asm_exc_overflow), #if defined(CONFIG_IA32_EMULATION) - SYSG(IA32_SYSCALL_VECTOR, asm_int80_emulation), + SYSG(IA32_SYSCALL_VECTOR, entry_INT80_compat), #elif defined(CONFIG_X86_32) SYSG(IA32_SYSCALL_VECTOR, entry_INT80_32), #endif diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index aeb33e0a3f76..bbbfdd495ebd 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -704,7 +704,7 @@ static struct trap_array_entry trap_array[] = { TRAP_ENTRY(exc_int3, false ), TRAP_ENTRY(exc_overflow, false ), #ifdef CONFIG_IA32_EMULATION - TRAP_ENTRY(int80_emulation, false ), + { entry_INT80_compat, xen_entry_INT80_compat, false }, #endif TRAP_ENTRY(exc_page_fault, false ), TRAP_ENTRY(exc_divide_error, false ), diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S index 1a9cd18dfbd3..9e5e68008785 100644 --- a/arch/x86/xen/xen-asm.S +++ b/arch/x86/xen/xen-asm.S @@ -156,7 +156,7 @@ xen_pv_trap asm_xenpv_exc_machine_check #endif /* CONFIG_X86_MCE */ xen_pv_trap asm_exc_simd_coprocessor_error #ifdef CONFIG_IA32_EMULATION -xen_pv_trap asm_int80_emulation +xen_pv_trap entry_INT80_compat #endif xen_pv_trap asm_exc_xen_unknown_trap xen_pv_trap asm_exc_xen_hypervisor_callback -- 2.44.0
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