orion160 · September 1, 2024 18:16 · Sep 1, 2024 · Sep 1, 2024 · Sep 1, 2024 · Sep 1, 2024
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -118,6 +118,8 @@ Special care is taken with `X18` register which is reserved as a platform regist
 
 [LLVM LIBC cmake build rules](https://libc.llvm.org/dev/cmake_build_rules.html)
 
+[add_entrypoint_object definition](https://github.com/llvm/llvm-project/blob/main/libc/cmake/modules/LLVMLibCObjectRules.cmake)
+
 ### gnu naked
 `[[gnu::naked]]` attribute
 > Use this attribute on the ARM, AVR, MCORE, MSP430, NDS32, RL78, RX and SPU ports to indicate that the specified function does not need prologue/epilogue sequences generated by the compiler. It is up to the programmer to provide these sequences. The only statements that can be safely included in naked functions are asm statements that do not have operands. All other statements, including declarations of local variables, if statements, and so forth, should be avoided. Naked functions should be used to implement the body of an assembly function, while allowing the compiler to construct the requisite function declaration for the assembler.

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -114,8 +114,11 @@ Special care is taken with `X18` register which is reserved as a platform regist
 
 ## Misc
 
-TODO: investigate on `add_entrypoint_object` cmake
+### add_entrypoint_object 
 
+[LLVM LIBC cmake build rules](https://libc.llvm.org/dev/cmake_build_rules.html)
+
+### gnu naked
 `[[gnu::naked]]` attribute
 > Use this attribute on the ARM, AVR, MCORE, MSP430, NDS32, RL78, RX and SPU ports to indicate that the specified function does not need prologue/epilogue sequences generated by the compiler. It is up to the programmer to provide these sequences. The only statements that can be safely included in naked functions are asm statements that do not have operands. All other statements, including declarations of local variables, if statements, and so forth, should be avoided. Naked functions should be used to implement the body of an assembly function, while allowing the compiler to construct the requisite function declaration for the assembler.
 

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -8,6 +8,8 @@
 
 > Pointer Authentication
 
+[USENIX Security '19 - PAC it up: Towards Pointer Integrity using ARM Pointer Authentication](https://www.youtube.com/watch?v=UD1KKHyPnZ4)
+
 ### Instructions
 
 > There are two main operations needed for Pointer Authentication: computing and adding a PAC, and verifying a

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -24,6 +24,8 @@ exception and an authentication failure by checking the pattern that the AUT ins
 
 ### PACIBSP & AUTIBSP
 
+> Pointer Authentication Code for Instruction Base Stack Pointer
+> 
 ## BTI
 
 > Branch Target Identification

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -8,7 +8,7 @@
 
 > Pointer Authentication
 
-## Instructions
+### Instructions
 
 > There are two main operations needed for Pointer Authentication: computing and adding a PAC, and verifying a
 PAC and restoring the pointer value. These are handled by the PAC* and AUT* sets of instructions respectively. If

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -10,17 +10,19 @@
 
 ## Instructions
 
-### PACIASP
+> There are two main operations needed for Pointer Authentication: computing and adding a PAC, and verifying a
+PAC and restoring the pointer value. These are handled by the PAC* and AUT* sets of instructions respectively. If
+verification fails during the AUT instruction, the processor replaces the PAC with a specific pattern that makes the
+pointer value an illegal address. The actual error detection happens through the illegal address exception when an
+invalid pointer is dereferenced. This design decouples error handling from the instruction and removes the need
+to use additional instructions for error handling. The exception handler can distinguish between an illegal address
+exception and an authentication failure by checking the pattern that the AUT instruction uses to signal the error.
 
-> Pointer Authentication Code for Instruction Address Stack Pointer
-
-### PACIBSP
+### PACIASP & AUTIASP
 
-> Pointer Authentication Code for Instruction Address Base Stack Pointer
-
-### AUTIASP
+> Pointer Authentication Code for Instruction Address Stack Pointer
 
-### AUTIBSP
+### PACIBSP & AUTIBSP
 
 ## BTI
 

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -12,12 +12,16 @@
 
 ### PACIASP
 
-> Pointer Authentication Code for Instruction Address Stack Pointer)
+> Pointer Authentication Code for Instruction Address Stack Pointer
 
 ### PACIBSP
 
 > Pointer Authentication Code for Instruction Address Base Stack Pointer
 
+### AUTIASP
+
+### AUTIBSP
+
 ## BTI
 
 > Branch Target Identification

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -8,6 +8,16 @@
 
 > Pointer Authentication
 
+## Instructions
+
+### PACIASP
+
+> Pointer Authentication Code for Instruction Address Stack Pointer)
+
+### PACIBSP
+
+> Pointer Authentication Code for Instruction Address Base Stack Pointer
+
 ## BTI
 
 > Branch Target Identification

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -97,6 +97,7 @@ Special care is taken with `X18` register which is reserved as a platform regist
 TODO: investigate on `add_entrypoint_object` cmake
 
 `[[gnu::naked]]` attribute
+> Use this attribute on the ARM, AVR, MCORE, MSP430, NDS32, RL78, RX and SPU ports to indicate that the specified function does not need prologue/epilogue sequences generated by the compiler. It is up to the programmer to provide these sequences. The only statements that can be safely included in naked functions are asm statements that do not have operands. All other statements, including declarations of local variables, if statements, and so forth, should be avoided. Naked functions should be used to implement the body of an assembly function, while allowing the compiler to construct the requisite function declaration for the assembler.
 
 [Attributes reference](https://clang.llvm.org/docs/AttributeReference.html)
 

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -97,3 +97,7 @@ Special care is taken with `X18` register which is reserved as a platform regist
 TODO: investigate on `add_entrypoint_object` cmake
 
 `[[gnu::naked]]` attribute
+
+[Attributes reference](https://clang.llvm.org/docs/AttributeReference.html)
+
+![image](https://gist.github.com/user-attachments/assets/5445e4c2-c15a-457a-87a3-1e5cc8dd2886)
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -96,4 +96,4 @@ Special care is taken with `X18` register which is reserved as a platform regist
 
 TODO: investigate on `add_entrypoint_object` cmake
 
-[[gnu::naked]] attribute
+`[[gnu::naked]]` attribute
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -95,3 +95,5 @@ Special care is taken with `X18` register which is reserved as a platform regist
 ## Misc
 
 TODO: investigate on `add_entrypoint_object` cmake
+
+[[gnu::naked]] attribute
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -28,10 +28,14 @@ These routines can be used for error handling recovery, and are included in `<se
 
 Saves the current execution context into a variable of type `jmp_buf`. It returns `0` on the first call, and a value different from zero if program control is restored with `longjmp`.
 
+[impl](https://github.com/llvm/llvm-project/blob/main/libc/src/setjmp/aarch64/setjmp.cpp)
+
 ### longjmp
 
 Loads the execution context env saved by a previous call to `setjmp`. **If the function that called setjmp has exited, the behavior is undefined (in other words, only long jumps up the call stack are allowed).**
 
+[impl](https://github.com/llvm/llvm-project/blob/main/libc/src/setjmp/aarch64/longjmp.cpp)
+
 ## Example
 
 [GODBOLT](https://godbolt.org/z/je9qEYYYx)

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -86,7 +86,7 @@ int main(int argc, char **argv) {
 
 Special care is taken with `X18` register which is reserved as a platform register.
 
-`jmp_buf` is defined at [src](https://github.com/llvm/llvm-project/blob/2a6268d8f999d56a557079e7fd8ee8c4a4e9ac0c/libc/include/llvm-libc-types/jmp_buf.h). Which stores register states.
+`jmp_buf` is defined at [src](https://github.com/llvm/llvm-project/blob/main/libc/include/llvm-libc-types/jmp_buf.h). Which stores register states.
 
 ## Misc
 

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -87,3 +87,7 @@ int main(int argc, char **argv) {
 Special care is taken with `X18` register which is reserved as a platform register.
 
 `jmp_buf` is defined at [src](https://github.com/llvm/llvm-project/blob/2a6268d8f999d56a557079e7fd8ee8c4a4e9ac0c/libc/include/llvm-libc-types/jmp_buf.h). Which stores register states.
+
+## Misc
+
+TODO: investigate on `add_entrypoint_object` cmake
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -86,4 +86,4 @@ int main(int argc, char **argv) {
 
 Special care is taken with `X18` register which is reserved as a platform register.
 
-`jmp_buf` is defined at [src](https://github.com/llvm/llvm-project/blob/2a6268d8f999d56a557079e7fd8ee8c4a4e9ac0c/libc/include/llvm-libc-types/jmp_buf.h).
+`jmp_buf` is defined at [src](https://github.com/llvm/llvm-project/blob/2a6268d8f999d56a557079e7fd8ee8c4a4e9ac0c/libc/include/llvm-libc-types/jmp_buf.h). Which stores register states.
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -85,3 +85,5 @@ int main(int argc, char **argv) {
 ## Implementation
 
 Special care is taken with `X18` register which is reserved as a platform register.
+
+`jmp_buf` is defined at [src](https://github.com/llvm/llvm-project/blob/2a6268d8f999d56a557079e7fd8ee8c4a4e9ac0c/libc/include/llvm-libc-types/jmp_buf.h).
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -80,4 +80,8 @@ int main(int argc, char **argv) {
 
   return 0;
 }
-```
+```
+
+## Implementation
+
+Special care is taken with `X18` register which is reserved as a platform register.
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -31,3 +31,53 @@ Saves the current execution context into a variable of type `jmp_buf`. It return
 ### longjmp
 
 Loads the execution context env saved by a previous call to `setjmp`. **If the function that called setjmp has exited, the behavior is undefined (in other words, only long jumps up the call stack are allowed).**
+
+## Example
+
+[GODBOLT](https://godbolt.org/z/je9qEYYYx)
+
+```c
+#include <math.h>
+#include <setjmp.h>
+#include <stdio.h>
+
+typedef enum { DIV_BY_ZERO = 1 } division_exceptions;
+
+jmp_buf divide_exception_h;
+
+float divide(float x, float y) {
+  if (y < 1e-6) {
+    longjmp(divide_exception_h, DIV_BY_ZERO);
+  }
+
+  return x / y;
+}
+
+int main(int argc, char **argv) {
+  switch (setjmp(divide_exception_h)) {
+  case 0:
+    float a = 1.0f;
+    float b = 2.0f;
+    float r = divide(a, b);
+    printf("%f = %f / %f\n", r, a, b);
+    break;
+  case DIV_BY_ZERO:
+    printf("Cannot divide by zero...\n");
+    break;
+  }
+
+  switch (setjmp(divide_exception_h)) {
+  case 0:
+    float a = 1.0f;
+    float b = 0.0f;
+    float r = divide(a, b);
+    printf("%f = %f / %f\n", r, a, b);
+    break;
+  case DIV_BY_ZERO:
+    printf("Cannot divide by zero...\n");
+    break;
+  }
+
+  return 0;
+}
+```
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -30,4 +30,4 @@ Saves the current execution context into a variable of type `jmp_buf`. It return
 
 ### longjmp
 
-Loads the execution context env saved by a previous call to `setjmp`.
+Loads the execution context env saved by a previous call to `setjmp`. **If the function that called setjmp has exited, the behavior is undefined (in other words, only long jumps up the call stack are allowed).**
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -29,3 +29,5 @@ These routines can be used for error handling recovery, and are included in `<se
 Saves the current execution context into a variable of type `jmp_buf`. It returns `0` on the first call, and a value different from zero if program control is restored with `longjmp`.
 
 ### longjmp
+
+Loads the execution context env saved by a previous call to `setjmp`.
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -26,4 +26,6 @@ These routines can be used for error handling recovery, and are included in `<se
 
 ### setjmp
 
+Saves the current execution context into a variable of type `jmp_buf`. It returns `0` on the first call, and a value different from zero if program control is restored with `longjmp`.
+
 ### longjmp
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -22,7 +22,7 @@
 
 ## libc functions
 
-These routines can be used for error handling recovery, and are included int ´<setjmp.h>´
+These routines can be used for error handling recovery, and are included in `<setjmp.h>`
 
 ### setjmp
 

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -22,6 +22,8 @@
 
 ## libc functions
 
+These routines can be used for error handling recovery, and are included int ´<setjmp.h>´
+
 ### setjmp
 
 ### longjmp
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -19,3 +19,9 @@
 ## Procedura call
 
 **AAPCS64** -> ARM Architecture Procedure Call Standard for 64-bit
+
+## libc functions
+
+### setjmp
+
+### longjmp
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -15,3 +15,7 @@
 ## MTE
 
 > Memory Tagging Extension
+
+## Procedura call
+
+**AAPCS64** -> ARM Architecture Procedure Call Standard for 64-bit
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -10,6 +10,8 @@
 
 ## BTI
 
+> Branch Target Identification
+
 ## MTE
 
-> Memory tagging extension
+> Memory Tagging Extension
diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -1,5 +1,7 @@
 # LLVM libc AArch64 setjmp/longjmp
 
+[commit](https://github.com/llvm/llvm-project/commit/2a6268d8f999)
+
 ## AArch64 extensions
 
 ## PAC

diff --git a/llvm_aarch64_libc_setjmp+longjmp.md b/llvm_aarch64_libc_setjmp+longjmp.md
@@ -1 +1,13 @@
 # LLVM libc AArch64 setjmp/longjmp
+
+## AArch64 extensions
+
+## PAC
+
+> Pointer Authentication
+
+## BTI
+
+## MTE
+
+> Memory tagging extension
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