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Move EnsureReadable() and co. to top of source file.

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Bartosz Taudul 2021-10-21 00:06:14 +02:00
parent 6d490ffd28
commit ff54317a87
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1 changed files with 140 additions and 140 deletions
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280
client/TracyProfiler.cpp
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@ -113,6 +113,146 @@ extern "C" typedef BOOL (WINAPI *t_GetLogicalProcessorInformationEx)( LOGICAL_PR
namespace tracy
{
#ifdef __ANDROID__
// Implementation helpers of EnsureReadable(address).
// This is so far only needed on Android, where it is common for libraries to be mapped
// with only executable, not readable, permissions. Typical example (line from /proc/self/maps):
/*
746b63b000-746b6dc000 --xp 00042000 07:48 35 /apex/com.android.runtime/lib64/bionic/libc.so
*/
// See https://github.com/wolfpld/tracy/issues/125 .
// To work around this, we parse /proc/self/maps and we use mprotect to set read permissions
// on any mappings that contain symbols addresses hit by HandleSymbolCodeQuery.
namespace {
// Holds some information about a single memory mapping.
struct MappingInfo {
// Start of address range. Inclusive.
uintptr_t start_address;
// End of address range. Exclusive, so the mapping is the half-open interval
// [start, end) and its length in bytes is `end - start`. As in /proc/self/maps.
uintptr_t end_address;
// Read/Write/Executable permissions.
bool perm_r, perm_w, perm_x;
};
} // anonymous namespace
// Internal implementation helper for LookUpMapping(address).
//
// Parses /proc/self/maps returning a vector<MappingInfo>.
// /proc/self/maps is assumed to be sorted by ascending address, so the resulting
// vector is sorted by ascending address too.
static std::vector<MappingInfo> ParseMappings()
{
std::vector<MappingInfo> result;
FILE* file = fopen( "/proc/self/maps", "r" );
if( !file ) return result;
char line[1024];
while( fgets( line, sizeof( line ), file ) )
{
uintptr_t start_addr;
uintptr_t end_addr;
if( sscanf( line, "%lx-%lx", &start_addr, &end_addr ) != 2 ) continue;
char* first_space = strchr( line, ' ' );
if( !first_space ) continue;
char* perm = first_space + 1;
char* second_space = strchr( perm, ' ' );
if( !second_space || second_space - perm != 4 ) continue;
result.emplace_back();
auto& mapping = result.back();
mapping.start_address = start_addr;
mapping.end_address = end_addr;
mapping.perm_r = perm[0] == 'r';
mapping.perm_w = perm[1] == 'w';
mapping.perm_x = perm[2] == 'x';
}
fclose( file );
return result;
}
// Internal implementation helper for LookUpMapping(address).
//
// Takes as input an `address` and a known vector `mappings`, assumed to be
// sorted by increasing addresses, as /proc/self/maps seems to be.
// Returns a pointer to the MappingInfo describing the mapping that this
// address belongs to, or nullptr if the address isn't in `mappings`.
static MappingInfo* LookUpMapping(std::vector<MappingInfo>& mappings, uintptr_t address)
{
// Comparison function for std::lower_bound. Returns true if all addresses in `m1`
// are lower than `addr`.
auto Compare = []( const MappingInfo& m1, uintptr_t addr ) {
// '<=' because the address ranges are half-open intervals, [start, end).
return m1.end_address <= addr;
};
auto iter = std::lower_bound( mappings.begin(), mappings.end(), address, Compare );
if( iter == mappings.end() || iter->start_address > address) {
return nullptr;
}
return &*iter;
}
// Internal implementation helper for EnsureReadable(address).
//
// Takes as input an `address` and returns a pointer to a MappingInfo
// describing the mapping that this address belongs to, or nullptr if
// the address isn't in any known mapping.
//
// This function is stateful and not reentrant (assumes to be called from
// only one thread). It holds a vector of mappings parsed from /proc/self/maps.
//
// Attempts to react to mappings changes by re-parsing /proc/self/maps.
static MappingInfo* LookUpMapping(uintptr_t address)
{
// Static state managed by this function. Not constant, we mutate that state as
// we turn some mappings readable. Initially parsed once here, updated as needed below.
static std::vector<MappingInfo> s_mappings = ParseMappings();
MappingInfo* mapping = LookUpMapping( s_mappings, address );
if( mapping ) return mapping;
// This address isn't in any known mapping. Try parsing again, maybe
// mappings changed.
s_mappings = ParseMappings();
return LookUpMapping( s_mappings, address );
}
// Internal implementation helper for EnsureReadable(address).
//
// Attempts to make the specified `mapping` readable if it isn't already.
// Returns true if and only if the mapping is readable.
static bool EnsureReadable( MappingInfo& mapping )
{
if( mapping.perm_r )
{
// The mapping is already readable.
return true;
}
int prot = PROT_READ;
if( mapping.perm_w ) prot |= PROT_WRITE;
if( mapping.perm_x ) prot |= PROT_EXEC;
if( mprotect( reinterpret_cast<void*>( mapping.start_address ),
mapping.end_address - mapping.start_address, prot ) == -1 )
{
// Failed to make the mapping readable. Shouldn't happen, hasn't
// been observed yet. If it happened in practice, we should consider
// adding a bool to MappingInfo to track this to avoid retrying mprotect
// everytime on such mappings.
return false;
}
// The mapping is now readable. Update `mapping` so the next call will be fast.
mapping.perm_r = true;
return true;
}
// Attempts to set the read permission on the entire mapping containing the
// specified address. Returns true if and only if the mapping is now readable.
static bool EnsureReadable( uintptr_t address )
{
MappingInfo* mapping = LookUpMapping(address);
return mapping && EnsureReadable( *mapping );
}
#endif // defined __ANDROID__
#ifndef TRACY_DELAYED_INIT
struct InitTimeWrapper
@ -3228,146 +3368,6 @@ void Profiler::HandleParameter( uint64_t payload )
AckServerQuery();
}
#ifdef __ANDROID__
// Implementation helpers of EnsureReadable(address).
// This is so far only needed on Android, where it is common for libraries to be mapped
// with only executable, not readable, permissions. Typical example (line from /proc/self/maps):
/*
746b63b000-746b6dc000 --xp 00042000 07:48 35 /apex/com.android.runtime/lib64/bionic/libc.so
*/
// See https://github.com/wolfpld/tracy/issues/125 .
// To work around this, we parse /proc/self/maps and we use mprotect to set read permissions
// on any mappings that contain symbols addresses hit by HandleSymbolCodeQuery.
namespace {
// Holds some information about a single memory mapping.
struct MappingInfo {
// Start of address range. Inclusive.
uintptr_t start_address;
// End of address range. Exclusive, so the mapping is the half-open interval
// [start, end) and its length in bytes is `end - start`. As in /proc/self/maps.
uintptr_t end_address;
// Read/Write/Executable permissions.
bool perm_r, perm_w, perm_x;
};
} // anonymous namespace
// Internal implementation helper for LookUpMapping(address).
//
// Parses /proc/self/maps returning a vector<MappingInfo>.
// /proc/self/maps is assumed to be sorted by ascending address, so the resulting
// vector is sorted by ascending address too.
static std::vector<MappingInfo> ParseMappings()
{
std::vector<MappingInfo> result;
FILE* file = fopen( "/proc/self/maps", "r" );
if( !file ) return result;
char line[1024];
while( fgets( line, sizeof( line ), file ) )
{
uintptr_t start_addr;
uintptr_t end_addr;
if( sscanf( line, "%lx-%lx", &start_addr, &end_addr ) != 2 ) continue;
char* first_space = strchr( line, ' ' );
if( !first_space ) continue;
char* perm = first_space + 1;
char* second_space = strchr( perm, ' ' );
if( !second_space || second_space - perm != 4 ) continue;
result.emplace_back();
auto& mapping = result.back();
mapping.start_address = start_addr;
mapping.end_address = end_addr;
mapping.perm_r = perm[0] == 'r';
mapping.perm_w = perm[1] == 'w';
mapping.perm_x = perm[2] == 'x';
}
fclose( file );
return result;
}
// Internal implementation helper for LookUpMapping(address).
//
// Takes as input an `address` and a known vector `mappings`, assumed to be
// sorted by increasing addresses, as /proc/self/maps seems to be.
// Returns a pointer to the MappingInfo describing the mapping that this
// address belongs to, or nullptr if the address isn't in `mappings`.
static MappingInfo* LookUpMapping(std::vector<MappingInfo>& mappings, uintptr_t address)
{
// Comparison function for std::lower_bound. Returns true if all addresses in `m1`
// are lower than `addr`.
auto Compare = []( const MappingInfo& m1, uintptr_t addr ) {
// '<=' because the address ranges are half-open intervals, [start, end).
return m1.end_address <= addr;
};
auto iter = std::lower_bound( mappings.begin(), mappings.end(), address, Compare );
if( iter == mappings.end() || iter->start_address > address) {
return nullptr;
}
return &*iter;
}
// Internal implementation helper for EnsureReadable(address).
//
// Takes as input an `address` and returns a pointer to a MappingInfo
// describing the mapping that this address belongs to, or nullptr if
// the address isn't in any known mapping.
//
// This function is stateful and not reentrant (assumes to be called from
// only one thread). It holds a vector of mappings parsed from /proc/self/maps.
//
// Attempts to react to mappings changes by re-parsing /proc/self/maps.
static MappingInfo* LookUpMapping(uintptr_t address)
{
// Static state managed by this function. Not constant, we mutate that state as
// we turn some mappings readable. Initially parsed once here, updated as needed below.
static std::vector<MappingInfo> s_mappings = ParseMappings();
MappingInfo* mapping = LookUpMapping( s_mappings, address );
if( mapping ) return mapping;
// This address isn't in any known mapping. Try parsing again, maybe
// mappings changed.
s_mappings = ParseMappings();
return LookUpMapping( s_mappings, address );
}
// Internal implementation helper for EnsureReadable(address).
//
// Attempts to make the specified `mapping` readable if it isn't already.
// Returns true if and only if the mapping is readable.
static bool EnsureReadable( MappingInfo& mapping )
{
if( mapping.perm_r )
{
// The mapping is already readable.
return true;
}
int prot = PROT_READ;
if( mapping.perm_w ) prot |= PROT_WRITE;
if( mapping.perm_x ) prot |= PROT_EXEC;
if( mprotect( reinterpret_cast<void*>( mapping.start_address ),
mapping.end_address - mapping.start_address, prot ) == -1 )
{
// Failed to make the mapping readable. Shouldn't happen, hasn't
// been observed yet. If it happened in practice, we should consider
// adding a bool to MappingInfo to track this to avoid retrying mprotect
// everytime on such mappings.
return false;
}
// The mapping is now readable. Update `mapping` so the next call will be fast.
mapping.perm_r = true;
return true;
}
// Attempts to set the read permission on the entire mapping containing the
// specified address. Returns true if and only if the mapping is now readable.
static bool EnsureReadable( uintptr_t address )
{
MappingInfo* mapping = LookUpMapping(address);
return mapping && EnsureReadable( *mapping );
}
#endif // defined __ANDROID__
void Profiler::HandleSymbolQuery( uint64_t symbol )
{
#ifdef TRACY_HAS_CALLSTACK