pw_cpu_exception_cortex_m: Remove packed attributes from structs
Removes the packed attributes from the CpuState structs to ensure they
can be safely directly accessed without a risk of unaligned access to
satisfy `-Werror=address-of-packed-member`.
To ensure it continues to be correct compared to our assembly,
static_asserts were added to verify there is no unexpected padding.
Change-Id: I3bd24adea17e8d8c3d0240a8182658489ca9baa0
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/78184
Reviewed-by: Armando Montanez <amontanez@google.com>
Commit-Queue: Ewout van Bekkum <ewout@google.com>
Pigweed-Auto-Submit: Ewout van Bekkum <ewout@google.com>
diff --git a/pw_cpu_exception_cortex_m/public/pw_cpu_exception_cortex_m/cpu_state.h b/pw_cpu_exception_cortex_m/public/pw_cpu_exception_cortex_m/cpu_state.h
index 51482ae..4aea5e4 100644
--- a/pw_cpu_exception_cortex_m/public/pw_cpu_exception_cortex_m/cpu_state.h
+++ b/pw_cpu_exception_cortex_m/public/pw_cpu_exception_cortex_m/cpu_state.h
@@ -34,7 +34,7 @@
constexpr uintptr_t kUndefinedPcLrOrPsrRegValue = 0xFFFF'FFFF;
// This is dictated by ARMv7-M architecture. Do not change.
-PW_PACKED(struct) ExceptionRegisters {
+struct ExceptionRegisters {
uint32_t r0;
uint32_t r1;
uint32_t r2;
@@ -44,9 +44,11 @@
uint32_t pc; // Program counter, note this may be invalid.
uint32_t psr; // Program status register, note this may be invalid.
};
+static_assert(sizeof(ExceptionRegisters) == (sizeof(uint32_t) * 8),
+ "There's unexpected padding.");
// This is dictated by ARMv7-M architecture. Do not change.
-PW_PACKED(struct) ExceptionRegistersFpu {
+struct ExceptionRegistersFpu {
uint32_t s0;
uint32_t s1;
uint32_t s2;
@@ -66,6 +68,8 @@
uint32_t fpscr;
uint32_t reserved;
};
+static_assert(sizeof(ExceptionRegistersFpu) == (sizeof(uint32_t) * 18),
+ "There's unexpected padding.");
// Bit in the PSR that indicates CPU added an extra word on the stack to
// align it during context save for an exception.
@@ -76,7 +80,7 @@
// values are populated in assembly).
//
// NOTE: Memory mapped registers are NOT restored upon fault return!
-PW_PACKED(struct) ExtraRegisters {
+struct ExtraRegisters {
// Memory mapped registers.
uint32_t cfsr;
uint32_t mmfar;
@@ -103,10 +107,17 @@
uint32_t r10;
uint32_t r11;
};
+static_assert(sizeof(ExtraRegisters) ==
+#if _PW_ARCH_ARM_V8M_MAINLINE
+ (sizeof(uint32_t) * 20),
+#else // !_PW_ARCH_ARM_V8M_MAINLINE
+ (sizeof(uint32_t) * 18),
+#endif // _PW_ARCH_ARM_V8M_MAINLINE
+ "There's unexpected padding.");
} // namespace pw::cpu_exception::cortex_m
-PW_PACKED(struct) pw_cpu_exception_State {
+struct pw_cpu_exception_State {
pw::cpu_exception::cortex_m::ExtraRegisters extended;
pw::cpu_exception::cortex_m::ExceptionRegisters base;
// TODO(amontanez): FPU registers may or may not be here as well. Make the
