1 #include "pci_handler.hpp"
2
3 #include <fcntl.h>
4
5 #include <stdplus/fd/managed.hpp>
6 #include <stdplus/fd/mmap.hpp>
7 #include <stdplus/print.hpp>
8
9 #include <cstdint>
10 #include <cstring>
11 #include <format>
12 #include <memory>
13 #include <span>
14 #include <vector>
15
16 namespace bios_bmc_smm_error_logger
17 {
18
PciDataHandler(uint32_t regionAddress,size_t regionSize,std::unique_ptr<stdplus::fd::Fd> fd)19 PciDataHandler::PciDataHandler(uint32_t regionAddress, size_t regionSize,
20 std::unique_ptr<stdplus::fd::Fd> fd) :
21 regionSize(regionSize), fd(std::move(fd)),
22 mmap(stdplus::fd::MMap(
23 *this->fd, regionSize, stdplus::fd::ProtFlags{PROT_READ | PROT_WRITE},
24 stdplus::fd::MMapFlags{stdplus::fd::MMapAccess::Shared}, regionAddress))
25 {}
26
read(const uint32_t offset,const uint32_t length)27 std::vector<uint8_t> PciDataHandler::read(const uint32_t offset,
28 const uint32_t length)
29 {
30 if (offset > regionSize || length == 0)
31 {
32 stdplus::print(stderr,
33 "[read] Offset [{}] was bigger than regionSize [{}] "
34 "OR length [{}] was equal to 0\n",
35 offset, regionSize, length);
36 return {};
37 }
38
39 // Read up to regionSize in case the offset + length overflowed
40 uint32_t finalLength =
41 (offset + length < regionSize) ? length : regionSize - offset;
42 std::vector<uint8_t> results(finalLength);
43
44 // Use a volatile pointer to ensure every access reads directly from the
45 // memory-mapped region, preventing compiler optimizations like caching.
46 const volatile uint8_t* src =
47 reinterpret_cast<volatile const uint8_t*>(mmap.get().data() + offset);
48
49 // Perform a byte-by-byte copy to avoid undefined behavior with memcpy on
50 // volatile memory.
51 for (uint32_t i = 0; i < finalLength; ++i)
52 {
53 results[i] = src[i];
54 }
55 return results;
56 }
57
write(const uint32_t offset,const std::span<const uint8_t> bytes)58 uint32_t PciDataHandler::write(const uint32_t offset,
59 const std::span<const uint8_t> bytes)
60 {
61 const size_t length = bytes.size();
62 if (offset > regionSize || length == 0)
63 {
64 stdplus::print(stderr,
65 "[write] Offset [{}] was bigger than regionSize [{}] "
66 "OR length [{}] was equal to 0\n",
67 offset, regionSize, length);
68 return 0;
69 }
70
71 // Write up to regionSize in case the offset + length overflowed
72 uint16_t finalLength =
73 (offset + length < regionSize) ? length : regionSize - offset;
74 // Use a volatile pointer to ensure every access writes directly to the
75 // memory-mapped region.
76 volatile uint8_t* dest =
77 reinterpret_cast<volatile uint8_t*>(mmap.get().data() + offset);
78
79 // Perform a byte-by-byte copy to ensure volatile semantics.
80 for (uint16_t i = 0; i < finalLength; ++i)
81 {
82 dest[i] = bytes[i];
83 }
84 return finalLength;
85 }
86
getMemoryRegionSize()87 uint32_t PciDataHandler::getMemoryRegionSize()
88 {
89 return regionSize;
90 }
91
92 } // namespace bios_bmc_smm_error_logger
93