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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/TemporaryChange.h>
#include <Kernel/Arch/x86/SmapDisabler.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/KSyms.h>
#include <Kernel/Process.h>
#include <Kernel/Scheduler.h>
#include <Kernel/Sections.h>
namespace Kernel {
FlatPtr g_lowest_kernel_symbol_address = 0xffffffff;
FlatPtr g_highest_kernel_symbol_address = 0;
bool g_kernel_symbols_available = false;
extern "C" {
__attribute__((section(".kernel_symbols"))) char kernel_symbols[5 * MiB] {};
}
static KernelSymbol* s_symbols;
static size_t s_symbol_count = 0;
static u8 parse_hex_digit(char nibble)
{
if (nibble >= '0' && nibble <= '9')
return nibble - '0';
VERIFY(nibble >= 'a' && nibble <= 'f');
return 10 + (nibble - 'a');
}
FlatPtr address_for_kernel_symbol(const StringView& name)
{
for (size_t i = 0; i < s_symbol_count; ++i) {
const auto& symbol = s_symbols[i];
if (name == symbol.name)
return symbol.address;
}
return 0;
}
const KernelSymbol* symbolicate_kernel_address(FlatPtr address)
{
if (address < g_lowest_kernel_symbol_address || address > g_highest_kernel_symbol_address)
return nullptr;
for (unsigned i = 0; i < s_symbol_count; ++i) {
if (address < s_symbols[i + 1].address)
return &s_symbols[i];
}
return nullptr;
}
UNMAP_AFTER_INIT static void load_kernel_symbols_from_data(ReadonlyBytes const& buffer)
{
g_lowest_kernel_symbol_address = 0xffffffff;
g_highest_kernel_symbol_address = 0;
auto* bufptr = (const char*)buffer.data();
auto* start_of_name = bufptr;
FlatPtr address = 0;
for (size_t i = 0; i < 8; ++i)
s_symbol_count = (s_symbol_count << 4) | parse_hex_digit(*(bufptr++));
s_symbols = static_cast<KernelSymbol*>(kmalloc_eternal(sizeof(KernelSymbol) * s_symbol_count));
++bufptr; // skip newline
dmesgln("Loading kernel symbol table...");
size_t current_symbol_index = 0;
while ((u8 const*)bufptr < buffer.data() + buffer.size()) {
for (size_t i = 0; i < 8; ++i)
address = (address << 4) | parse_hex_digit(*(bufptr++));
bufptr += 3;
start_of_name = bufptr;
while (*(++bufptr)) {
if (*bufptr == '\n') {
break;
}
}
auto& ksym = s_symbols[current_symbol_index];
ksym.address = kernel_load_base + address;
char* name = static_cast<char*>(kmalloc_eternal((bufptr - start_of_name) + 1));
memcpy(name, start_of_name, bufptr - start_of_name);
name[bufptr - start_of_name] = '\0';
ksym.name = name;
if (ksym.address < g_lowest_kernel_symbol_address)
g_lowest_kernel_symbol_address = ksym.address;
if (ksym.address > g_highest_kernel_symbol_address)
g_highest_kernel_symbol_address = ksym.address;
++bufptr;
++current_symbol_index;
}
g_kernel_symbols_available = true;
}
NEVER_INLINE static void dump_backtrace_impl(FlatPtr base_pointer, bool use_ksyms, PrintToScreen print_to_screen)
{
#define PRINT_LINE(fmtstr, ...) \
do { \
if (print_to_screen == PrintToScreen::No) \
dbgln(fmtstr, __VA_ARGS__); \
else \
critical_dmesgln(fmtstr, __VA_ARGS__); \
} while (0)
SmapDisabler disabler;
if (use_ksyms && !g_kernel_symbols_available) {
Processor::halt();
return;
}
struct RecognizedSymbol {
FlatPtr address;
const KernelSymbol* symbol { nullptr };
};
constexpr size_t max_recognized_symbol_count = 256;
RecognizedSymbol recognized_symbols[max_recognized_symbol_count];
size_t recognized_symbol_count = 0;
if (use_ksyms) {
FlatPtr copied_stack_ptr[2];
for (FlatPtr* stack_ptr = (FlatPtr*)base_pointer; stack_ptr && recognized_symbol_count < max_recognized_symbol_count; stack_ptr = (FlatPtr*)copied_stack_ptr[0]) {
if ((FlatPtr)stack_ptr < kernel_load_base)
break;
void* fault_at;
if (!safe_memcpy(copied_stack_ptr, stack_ptr, sizeof(copied_stack_ptr), fault_at))
break;
FlatPtr retaddr = copied_stack_ptr[1];
recognized_symbols[recognized_symbol_count++] = { retaddr, symbolicate_kernel_address(retaddr) };
}
} else {
void* fault_at;
FlatPtr copied_stack_ptr[2];
FlatPtr* stack_ptr = (FlatPtr*)base_pointer;
while (stack_ptr && safe_memcpy(copied_stack_ptr, stack_ptr, sizeof(copied_stack_ptr), fault_at)) {
FlatPtr retaddr = copied_stack_ptr[1];
PRINT_LINE("{:p} (next: {:p})", retaddr, stack_ptr ? (FlatPtr*)copied_stack_ptr[0] : 0);
stack_ptr = (FlatPtr*)copied_stack_ptr[0];
}
return;
}
VERIFY(recognized_symbol_count <= max_recognized_symbol_count);
for (size_t i = 0; i < recognized_symbol_count; ++i) {
auto& symbol = recognized_symbols[i];
if (!symbol.address)
break;
if (!symbol.symbol) {
PRINT_LINE("Kernel + {:p}", symbol.address - kernel_load_base);
continue;
}
size_t offset = symbol.address - symbol.symbol->address;
if (symbol.symbol->address == g_highest_kernel_symbol_address && offset > 4096)
PRINT_LINE("Kernel + {:p}", symbol.address - kernel_load_base);
else
PRINT_LINE("Kernel + {:p} {} +{:#x}", symbol.address - kernel_load_base, symbol.symbol->name, offset);
}
}
void dump_backtrace(PrintToScreen print_to_screen)
{
static bool in_dump_backtrace = false;
if (in_dump_backtrace)
return;
TemporaryChange change(in_dump_backtrace, true);
TemporaryChange disable_kmalloc_stacks(g_dump_kmalloc_stacks, false);
FlatPtr ebp;
asm volatile("movl %%ebp, %%eax"
: "=a"(ebp));
dump_backtrace_impl(ebp, g_kernel_symbols_available, print_to_screen);
}
UNMAP_AFTER_INIT void load_kernel_symbol_table()
{
auto kernel_symbols_size = strnlen(kernel_symbols, sizeof(kernel_symbols));
// If we're hitting this VERIFY the kernel symbol file has grown beyond
// the array size of kernel_symbols. Try making the array larger.
VERIFY(kernel_symbols_size != sizeof(kernel_symbols));
load_kernel_symbols_from_data({ kernel_symbols, kernel_symbols_size });
}
}
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