[PW_SID:1098362] riscv: Implement _THIS_IP_ using inline asm#1986
[PW_SID:1098362] riscv: Implement _THIS_IP_ using inline asm#1986linux-riscv-bot wants to merge 1 commit into
Conversation
Both GCC [1] and Clang [2] consider the generic version of _THIS_IP_ to
be broken:
#define _THIS_IP_ ({ __label__ __here; __here: (unsigned long)&&__here; })
In particular, the address of a label is only expected to be used with a
computed goto.
While the generic version more or less works today, it is known to be
brittle and may break with current and future optimizations. For
example, Clang -O2 always returns 1 when this function is inlined:
static inline unsigned long get_ip(void)
{ return ({ __label__ __here; __here: (unsigned long)&&__here; }); }
Fix it by overriding _THIS_IP_ in <asm/linkage.h> (which is included by
<linux/instruction_pointer.h>) using an architecture-specific inline asm
version. Additionally, avoiding taking the address of a label prevents
compilers from emitting spurious indirect branch targets (e.g. ENDBR or
BTI) under control-flow integrity schemes.
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120071 [1]
Link: llvm/llvm-project#138272 [2]
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Linux RISC-V bot <linux.riscv.bot@gmail.com>
|
Patch 1: "riscv: Implement THIS_IP using inline asm" |
|
Patch 1: "riscv: Implement THIS_IP using inline asm" |
|
Patch 1: "riscv: Implement THIS_IP using inline asm" |
|
Patch 1: "riscv: Implement THIS_IP using inline asm" |
|
Patch 1: "riscv: Implement THIS_IP using inline asm" |
|
Patch 1: "riscv: Implement THIS_IP using inline asm" |
|
Patch 1: "riscv: Implement THIS_IP using inline asm" |
|
Patch 1: "riscv: Implement THIS_IP using inline asm" |
|
Patch 1: "riscv: Implement THIS_IP using inline asm" |
|
Patch 1: "riscv: Implement THIS_IP using inline asm" |
|
Patch 1: "riscv: Implement THIS_IP using inline asm" |
|
Patch 1: "riscv: Implement THIS_IP using inline asm" |
2 participants
PR for series 1098362 applied to workflow__riscv__fixes
Name: riscv: Implement THIS_IP using inline asm
URL: https://patchwork.kernel.org/project/linux-riscv/list/?series=1098362
Version: 1