Skip to content

Safe fetch 64-bit value and pointer #247

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
zhengyu123 merged 5 commits into from
Jul 22, 2025
Merged

Safe fetch 64-bit value and pointer #247

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
6e2a715
v0
zhengyu123 Jul 18, 2025
ae754ea
v1
zhengyu123 Jul 21, 2025
d519dd2
Fix
zhengyu123 Jul 21, 2025
dce4c5f
v2
zhengyu123 Jul 21, 2025
27b5838
Remove old safe access handler
zhengyu123 Jul 21, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Next Next commit
v1
  • Loading branch information
@zhengyu123
zhengyu123 committed Jul 21, 2025
commit ae754ea899e9ace4f700e164415a60e835cce0ba
8 changes: 4 additions & 4 deletions ddprof-lib/src/main/cpp/safeAccess.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@
#include <ucontext.h>

extern "C" int safefetch32_cont(int* adr, int errValue);
extern "C" int safefetch64_cont(int64_t* adr, int64_t errValue);
extern "C" int64_t safefetch64_cont(int64_t* adr, int64_t errValue);

#ifdef __APPLE__
#if defined(__x86_64__)
Expand Down Expand Up @@ -74,7 +74,7 @@ extern "C" int safefetch64_cont(int64_t* adr, int64_t errValue);
.globl safefetch32_impl
.hidden safefetch32_impl
.type safefetch32_imp, %function
safefetch32_impl:
safefetch64_impl:
movl (%rdi), %eax
ret
.globl safefetch32_cont
Expand All @@ -86,7 +86,7 @@ extern "C" int safefetch64_cont(int64_t* adr, int64_t errValue);
.globl safefetch64_impl
.hidden safefetch64_impl
.type safefetch64_imp, %function
Copy link
Copy Markdown
Contributor

@r1viollet r1viollet Jul 23, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Looks like a typo ? This might be confusing for linkers / debuggers.

Copy link
Copy Markdown
Contributor Author

@zhengyu123 zhengyu123 Jul 23, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Oops, will fix it. Thanks!

safefetch32_impl:
safefetch64_impl:
movq (%rdi), %rax
ret
.globl safefetch64_cont
Expand Down Expand Up @@ -160,7 +160,7 @@ bool SafeAccess::handle_safefetch(int sig, void* context) {
uc->current_pc = (uintptr_t)safefetch32_cont;
return true;
} else if (pc == (uintptr_t)safefetch64_impl) {
uc->current_pc = (uintptr_t)safefetch32_cont;
uc->current_pc = (uintptr_t)safefetch64_cont;
return true;
}
}
Expand Down
10 changes: 5 additions & 5 deletions ddprof-lib/src/main/cpp/safeAccess.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@
#include <stdint.h>

extern "C" int safefetch32_impl(int* adr, int errValue);
extern "C" int safefetch64_impl(int64_t* adr, int64_t errValue);
extern "C" int64_t safefetch64_impl(int64_t* adr, int64_t errValue);

#ifdef __clang__
#define NOINLINE __attribute__((noinline))
Expand All @@ -39,7 +39,7 @@ class SafeAccess {
return safefetch32_impl(ptr, errorValue);
}

static inline int safeFetch64(int64_t* ptr, int64_t errorValue) {
static inline int64_t safeFetch64(int64_t* ptr, int64_t errorValue) {
return safefetch64_impl(ptr, errorValue);
}

Expand All @@ -54,10 +54,10 @@ class SafeAccess {
return static_cast<u32>(res);
}

static inline void *loadPtr(void **ptr, void *default_value) {
static inline void *loadPtr(void** ptr, void* default_value) {
#if defined(__x86_64__) || defined(__aarch64__)
int64_t res = safefetch64_impl((int64_t*)ptr, (int64_t)default_value);
return (void*)res;
int64_t res = safefetch64_impl((int64_t*)ptr, (int64_t)reinterpret_cast<uintptr_t>(default_value));
return (void*)static_cast<uintptr_t>(res);
#elif defined(__i386__) || defined(__arm__) || defined(__thumb__)
int res = safefetch32_impl((int*)ptr, (int)default_value);
return (void*)res;
Expand Down
32 changes: 32 additions & 0 deletions ddprof-lib/src/test/cpp/safefetch_ut.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
#include <gmock/gmock.h>
#include <gtest/gtest.h>
#include <climits>
#include <signal.h>

#include "safeAccess.h"
Expand Down Expand Up @@ -39,6 +40,12 @@ TEST_F(SafeFetchTest, validAccess32) {
int* p = &i;
int res = SafeAccess::safeFetch32(p, -1);
EXPECT_EQ(res, i);
i = INT_MAX;
res = SafeAccess::safeFetch32(p, -1);
EXPECT_EQ(res, i);
i = INT_MIN;
res = SafeAccess::safeFetch32(p, 0);
EXPECT_EQ(res, i);
}


Expand All @@ -55,6 +62,12 @@ TEST_F(SafeFetchTest, validAccess64) {
int64_t* p = &i;
int64_t res = SafeAccess::safeFetch64(p, -1);
EXPECT_EQ(res, i);
i = LONG_MIN;
res = SafeAccess::safeFetch64(p, -19);
EXPECT_EQ(res, i);
i = LONG_MAX;
res = SafeAccess::safeFetch64(p, -1);
EXPECT_EQ(res, i);
}

TEST_F(SafeFetchTest, invalidAccess64) {
Expand All @@ -64,3 +77,22 @@ TEST_F(SafeFetchTest, invalidAccess64) {
res = SafeAccess::safeFetch64(p, -2);
EXPECT_EQ(res, -2);
}

TEST_F(SafeFetchTest, validAccessPtr) {
char c = 'a';
void* p = (void*)&c;
void** pp = &p;
void* res = SafeAccess::loadPtr(pp, nullptr);
EXPECT_EQ(res, p);
}

TEST_F(SafeFetchTest, invalidAccessPtr) {
int a, b;
void* ap = (void*)&a;
void* bp = (void*)&b;
void** pp = nullptr;
void* res = SafeAccess::loadPtr(pp, ap);
EXPECT_EQ(res, ap);
res = SafeAccess::loadPtr(pp, bp);
EXPECT_EQ(res, bp);
}