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Kernel: Implement safe_* memory access functions for x86_64

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This commit is contained in:
Gunnar Beutner 2021-06-27 14:12:55 +02:00 • committed by Andreas Kling
parent 79ab9cce18
commit df530941cc
4 changed files with 57 additions and 120 deletions
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2
Kernel/Arch/x86/SafeMem.h
View file

@ -95,6 +95,6 @@ struct RegisterState;
}
}
bool handle_safe_access_fault(RegisterState& regs, u32 fault_address);
bool handle_safe_access_fault(RegisterState& regs, FlatPtr fault_address);
}

84
Kernel/Arch/x86/i386/SafeMem.cpp → Kernel/Arch/x86/common/SafeMem.cpp
View file

@ -51,8 +51,12 @@ NEVER_INLINE bool safe_memcpy(void* dest_ptr, const void* src_ptr, size_t n, voi
size_t size_ts = n / sizeof(size_t);
asm volatile(
"safe_memcpy_ins_1: \n"
#if ARCH(I386)
"rep movsl \n"
"safe_memcpy_1_faulted: \n" // handle_safe_access_fault() set edx to the fault address!
#else
"rep movsq \n"
#endif
"safe_memcpy_1_faulted: \n" // handle_safe_access_fault() set edx/rdx to the fault address!
: "=S"(src),
"=D"(dest),
"=c"(remainder),
@ -72,7 +76,7 @@ NEVER_INLINE bool safe_memcpy(void* dest_ptr, const void* src_ptr, size_t n, voi
asm volatile(
"safe_memcpy_ins_2: \n"
"rep movsb \n"
"safe_memcpy_2_faulted: \n" // handle_safe_access_fault() set edx to the fault address!
"safe_memcpy_2_faulted: \n" // handle_safe_access_fault() set edx/rdx to the fault address!
: "=c"(remainder),
[fault_at] "=d"(fault_at)
: "S"(src),
@ -100,7 +104,7 @@ NEVER_INLINE ssize_t safe_strnlen(const char* str, size_t max_n, void*& fault_at
"je 2f \n"
"inc %[count] \n"
"jmp 1b \n"
"safe_strnlen_faulted: \n" // handle_safe_access_fault() set edx to the fault address!
"safe_strnlen_faulted: \n" // handle_safe_access_fault() set edx/rdx to the fault address!
"xor %[count_on_error], %[count_on_error] \n"
"dec %[count_on_error] \n" // return -1 on fault
"2:"
@ -128,8 +132,12 @@ NEVER_INLINE bool safe_memset(void* dest_ptr, int c, size_t n, void*& fault_at)
expanded_c |= expanded_c << 16;
asm volatile(
"safe_memset_ins_1: \n"
#if ARCH(I386)
"rep stosl \n"
"safe_memset_1_faulted: \n" // handle_safe_access_fault() set edx to the fault address!
#else
"rep stosq \n"
#endif
"safe_memset_1_faulted: \n" // handle_safe_access_fault() set edx/rdx to the fault address!
: "=D"(dest),
"=c"(remainder),
[fault_at] "=d"(fault_at)
@ -148,7 +156,7 @@ NEVER_INLINE bool safe_memset(void* dest_ptr, int c, size_t n, void*& fault_at)
asm volatile(
"safe_memset_ins_2: \n"
"rep stosb \n"
"safe_memset_2_faulted: \n" // handle_safe_access_fault() set edx to the fault address!
"safe_memset_2_faulted: \n" // handle_safe_access_fault() set edx/rdx to the fault address!
: "=D"(dest),
"=c"(remainder),
[fault_at] "=d"(fault_at)
@ -251,45 +259,63 @@ NEVER_INLINE Optional<bool> safe_atomic_compare_exchange_relaxed(volatile u32* v
return did_exchange;
}
bool handle_safe_access_fault(RegisterState& regs, u32 fault_address)
bool handle_safe_access_fault(RegisterState& regs, FlatPtr fault_address)
{
if (regs.eip >= (FlatPtr)&start_of_safemem_text && regs.eip < (FlatPtr)&end_of_safemem_text) {
FlatPtr ip;
#if ARCH(I386)
ip = regs.eip;
#else
ip = regs.rip;
#endif
if (ip >= (FlatPtr)&start_of_safemem_text && ip < (FlatPtr)&end_of_safemem_text) {
// If we detect that the fault happened in safe_memcpy() safe_strnlen(),
// or safe_memset() then resume at the appropriate _faulted label
if (regs.eip == (FlatPtr)&safe_memcpy_ins_1)
regs.eip = (FlatPtr)&safe_memcpy_1_faulted;
else if (regs.eip == (FlatPtr)&safe_memcpy_ins_2)
regs.eip = (FlatPtr)&safe_memcpy_2_faulted;
else if (regs.eip == (FlatPtr)&safe_strnlen_ins)
regs.eip = (FlatPtr)&safe_strnlen_faulted;
else if (regs.eip == (FlatPtr)&safe_memset_ins_1)
regs.eip = (FlatPtr)&safe_memset_1_faulted;
else if (regs.eip == (FlatPtr)&safe_memset_ins_2)
regs.eip = (FlatPtr)&safe_memset_2_faulted;
if (ip == (FlatPtr)&safe_memcpy_ins_1)
ip = (FlatPtr)&safe_memcpy_1_faulted;
else if (ip == (FlatPtr)&safe_memcpy_ins_2)
ip = (FlatPtr)&safe_memcpy_2_faulted;
else if (ip == (FlatPtr)&safe_strnlen_ins)
ip = (FlatPtr)&safe_strnlen_faulted;
else if (ip == (FlatPtr)&safe_memset_ins_1)
ip = (FlatPtr)&safe_memset_1_faulted;
else if (ip == (FlatPtr)&safe_memset_ins_2)
ip = (FlatPtr)&safe_memset_2_faulted;
else
return false;
#if ARCH(I386)
regs.eip = ip;
regs.edx = fault_address;
#else
regs.rip = ip;
regs.rdx = fault_address;
#endif
return true;
}
if (regs.eip >= (FlatPtr)&start_of_safemem_atomic_text && regs.eip < (FlatPtr)&end_of_safemem_atomic_text) {
if (ip >= (FlatPtr)&start_of_safemem_atomic_text && ip < (FlatPtr)&end_of_safemem_atomic_text) {
// If we detect that a fault happened in one of the atomic safe_
// functions, resume at the appropriate _faulted label and set
// the edx register to 1 to indicate an error
if (regs.eip == (FlatPtr)&safe_atomic_fetch_add_relaxed_ins)
regs.eip = (FlatPtr)&safe_atomic_fetch_add_relaxed_faulted;
else if (regs.eip == (FlatPtr)&safe_atomic_exchange_relaxed_ins)
regs.eip = (FlatPtr)&safe_atomic_exchange_relaxed_faulted;
else if (regs.eip == (FlatPtr)&safe_atomic_load_relaxed_ins)
regs.eip = (FlatPtr)&safe_atomic_load_relaxed_faulted;
else if (regs.eip == (FlatPtr)&safe_atomic_store_relaxed_ins)
regs.eip = (FlatPtr)&safe_atomic_store_relaxed_faulted;
else if (regs.eip == (FlatPtr)&safe_atomic_compare_exchange_relaxed_ins)
regs.eip = (FlatPtr)&safe_atomic_compare_exchange_relaxed_faulted;
// the edx/rdx register to 1 to indicate an error
if (ip == (FlatPtr)&safe_atomic_fetch_add_relaxed_ins)
ip = (FlatPtr)&safe_atomic_fetch_add_relaxed_faulted;
else if (ip == (FlatPtr)&safe_atomic_exchange_relaxed_ins)
ip = (FlatPtr)&safe_atomic_exchange_relaxed_faulted;
else if (ip == (FlatPtr)&safe_atomic_load_relaxed_ins)
ip = (FlatPtr)&safe_atomic_load_relaxed_faulted;
else if (ip == (FlatPtr)&safe_atomic_store_relaxed_ins)
ip = (FlatPtr)&safe_atomic_store_relaxed_faulted;
else if (ip == (FlatPtr)&safe_atomic_compare_exchange_relaxed_ins)
ip = (FlatPtr)&safe_atomic_compare_exchange_relaxed_faulted;
else
return false;
#if ARCH(I386)
regs.eip = ip;
regs.edx = 1;
#else
regs.rip = ip;
regs.rdx = 1;
#endif
return true;
}
return false;

89
Kernel/Arch/x86/x86_64/SafeMem.cpp
View file

@ -1,89 +0,0 @@
/*
* Copyright (c) 2021, Gunnar Beutner <gbeutner@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Arch/x86/SafeMem.h>
#define CODE_SECTION(section_name) __attribute__((section(section_name)))
namespace Kernel {
CODE_SECTION(".text.safemem")
NEVER_INLINE bool safe_memcpy(void* dest_ptr, const void* src_ptr, size_t n, void*& fault_at)
{
(void)dest_ptr;
(void)src_ptr;
(void)n;
(void)fault_at;
TODO();
}
CODE_SECTION(".text.safemem")
NEVER_INLINE ssize_t safe_strnlen(const char* str, size_t max_n, void*& fault_at)
{
(void)str;
(void)max_n;
(void)fault_at;
TODO();
}
CODE_SECTION(".text.safemem")
NEVER_INLINE bool safe_memset(void* dest_ptr, int c, size_t n, void*& fault_at)
{
(void)dest_ptr;
(void)c;
(void)n;
(void)fault_at;
TODO();
}
CODE_SECTION(".text.safemem.atomic")
NEVER_INLINE Optional<u32> safe_atomic_fetch_add_relaxed(volatile u32* var, u32 val)
{
(void)var;
(void)val;
TODO();
}
CODE_SECTION(".text.safemem.atomic")
NEVER_INLINE Optional<u32> safe_atomic_exchange_relaxed(volatile u32* var, u32 val)
{
(void)var;
(void)val;
TODO();
}
CODE_SECTION(".text.safemem.atomic")
NEVER_INLINE Optional<u32> safe_atomic_load_relaxed(volatile u32* var)
{
(void)var;
TODO();
}
CODE_SECTION(".text.safemem.atomic")
NEVER_INLINE bool safe_atomic_store_relaxed(volatile u32* var, u32 val)
{
(void)var;
(void)val;
TODO();
}
CODE_SECTION(".text.safemem.atomic")
NEVER_INLINE Optional<bool> safe_atomic_compare_exchange_relaxed(volatile u32* var, u32& expected, u32 val)
{
(void)var;
(void)expected;
(void)val;
TODO();
}
bool handle_safe_access_fault(RegisterState& regs, u32 fault_address)
{
(void)regs;
(void)fault_address;
TODO();
}
}

2
Kernel/CMakeLists.txt
View file

@ -280,7 +280,6 @@ set(KERNEL_SOURCES
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/CPU.cpp
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/InterruptEntry.cpp
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/Processor.cpp
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/${KERNEL_ARCH}/SafeMem.cpp
)
set(KERNEL_SOURCES
@ -291,6 +290,7 @@ set(KERNEL_SOURCES
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/Interrupts.cpp
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/Processor.cpp
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/ProcessorInfo.cpp
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/SafeMem.cpp
${CMAKE_CURRENT_SOURCE_DIR}/Arch/x86/common/TrapFrame.cpp
)