From b285a1944e7c3a5256c08eb3b484227574c35b80 Mon Sep 17 00:00:00 2001 From: Andreas Kling Date: Sat, 9 Nov 2019 22:40:35 +0100 Subject: Kernel: Clear the x86 DF flag when entering the kernel The SysV ABI says that the DF flag should be clear on function entry. That means we have to clear it when jumping into the kernel from some random userspace context. --- Kernel/Arch/i386/CPU.cpp | 59 +++++++++++++++++++++++++----------------------- Kernel/Arch/i386/PIT.cpp | 1 + Kernel/Syscall.cpp | 1 + 3 files changed, 33 insertions(+), 28 deletions(-) diff --git a/Kernel/Arch/i386/CPU.cpp b/Kernel/Arch/i386/CPU.cpp index 738dcf35b3..1bbdb0bd50 100644 --- a/Kernel/Arch/i386/CPU.cpp +++ b/Kernel/Arch/i386/CPU.cpp @@ -55,6 +55,7 @@ asm( " pushw %ss\n" " popw %ds\n" " popw %es\n" + " cld\n" " call handle_irq\n" " popw %es\n" " popw %ds\n" @@ -82,6 +83,7 @@ asm( " popw %es\n" \ " popw %fs\n" \ " popw %gs\n" \ + " cld\n" \ " call exception_" #ec "_handler\n" \ " popw %gs\n" \ " popw %gs\n" \ @@ -92,35 +94,36 @@ asm( " add $0x4, %esp\n" \ " iret\n"); -#define EH_ENTRY_NO_CODE(ec) \ +#define EH_ENTRY_NO_CODE(ec) \ extern "C" void exception_##ec##_handler(RegisterDump); \ - extern "C" void exception_##ec##_entry(); \ - asm( \ - ".globl exception_" #ec "_entry\n" \ - "exception_" #ec "_entry: \n" \ - " pushl $0x0\n" \ - " pusha\n" \ - " pushw %ds\n" \ - " pushw %es\n" \ - " pushw %fs\n" \ - " pushw %gs\n" \ - " pushw %ss\n" \ - " pushw %ss\n" \ - " pushw %ss\n" \ - " pushw %ss\n" \ - " pushw %ss\n" \ - " popw %ds\n" \ - " popw %es\n" \ - " popw %fs\n" \ - " popw %gs\n" \ - " call exception_" #ec "_handler\n" \ - " popw %gs\n" \ - " popw %gs\n" \ - " popw %fs\n" \ - " popw %es\n" \ - " popw %ds\n" \ - " popa\n" \ - " add $0x4, %esp\n" \ + extern "C" void exception_##ec##_entry(); \ + asm( \ + ".globl exception_" #ec "_entry\n" \ + "exception_" #ec "_entry: \n" \ + " pushl $0x0\n" \ + " pusha\n" \ + " pushw %ds\n" \ + " pushw %es\n" \ + " pushw %fs\n" \ + " pushw %gs\n" \ + " pushw %ss\n" \ + " pushw %ss\n" \ + " pushw %ss\n" \ + " pushw %ss\n" \ + " pushw %ss\n" \ + " popw %ds\n" \ + " popw %es\n" \ + " popw %fs\n" \ + " popw %gs\n" \ + " cld\n" \ + " call exception_" #ec "_handler\n" \ + " popw %gs\n" \ + " popw %gs\n" \ + " popw %fs\n" \ + " popw %es\n" \ + " popw %ds\n" \ + " popa\n" \ + " add $0x4, %esp\n" \ " iret\n"); static void dump(const RegisterDump& regs) diff --git a/Kernel/Arch/i386/PIT.cpp b/Kernel/Arch/i386/PIT.cpp index b4861c3066..0a64e6d34f 100644 --- a/Kernel/Arch/i386/PIT.cpp +++ b/Kernel/Arch/i386/PIT.cpp @@ -27,6 +27,7 @@ asm( " popw %es\n" " popw %fs\n" " popw %gs\n" + " cld\n" " call timer_interrupt_handler\n" " popw %gs\n" " popw %gs\n" diff --git a/Kernel/Syscall.cpp b/Kernel/Syscall.cpp index 378a3e3e0b..9cc6cd365d 100644 --- a/Kernel/Syscall.cpp +++ b/Kernel/Syscall.cpp @@ -24,6 +24,7 @@ asm( " popw %es\n" " popw %fs\n" " popw %gs\n" + " cld\n" " call syscall_trap_entry\n" " popw %gs\n" " popw %gs\n" -- cgit v1.2.3