| Message ID | 20180811095235.1938-1-stefan@agner.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ARM: require GCC for FRAME_POINTER | expand |
On Sat, Aug 11, 2018 at 11:52 AM Stefan Agner <stefan@agner.ch> wrote: > > diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug > index 693f84392f1b..cb65cf67dfa2 100644 > --- a/arch/arm/Kconfig.debug > +++ b/arch/arm/Kconfig.debug > @@ -54,7 +54,7 @@ config DEBUG_WX > # n, but then RMK will have to kill you ;). > config FRAME_POINTER > bool > - depends on !THUMB2_KERNEL > + depends on !THUMB2_KERNEL && CC_IS_GCC > default y if !ARM_UNWIND || FUNCTION_GRAPH_TRACER > help > If you say N here, the resulting kernel will be slightly smaller and I suspect we actually need a bit more complexity here, as we have a couple of options that do something like: select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !X86 This means that in configurations without ARM_UNWIND, we still fail to build with clang. Maybe something like x86 would work, this currently has choice prompt "Choose kernel unwinder" default UNWINDER_ORC if X86_64 default UNWINDER_FRAME_POINTER if X86_32 config UNWINDER_ORC bool "ORC unwinder" depends on X86_64 select STACK_VALIDATION config UNWINDER_FRAME_POINTER bool "Frame pointer unwinder" select FRAME_POINTER config UNWINDER_GUESS bool "Guess unwinder" depends on EXPERT depends on !STACKDEPOT endchoice so we always get some form of unwinding, but have different levels of functionality in them. Implementing ORC on ARM might be nice, but that's a lot of work, so I'm not expecting you to do that. The simplest approach would be to always force ARM_UNWIND=y when not building with gcc: diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug index 43d598c9b1f9..b390ac99ba20 100644 --- a/arch/arm/Kconfig.debug +++ b/arch/arm/Kconfig.debug @@ -60,7 +60,7 @@ config FRAME_POINTER reported is severely limited. config ARM_UNWIND - bool "Enable stack unwinding support (EXPERIMENTAL)" + bool "Enable stack unwinding support (EXPERIMENTAL)" if CC_IS_GCC depends on AEABI default y help Arnd
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug index 693f84392f1b..cb65cf67dfa2 100644 --- a/arch/arm/Kconfig.debug +++ b/arch/arm/Kconfig.debug @@ -54,7 +54,7 @@ config DEBUG_WX # n, but then RMK will have to kill you ;). config FRAME_POINTER bool - depends on !THUMB2_KERNEL + depends on !THUMB2_KERNEL && CC_IS_GCC default y if !ARM_UNWIND || FUNCTION_GRAPH_TRACER help If you say N here, the resulting kernel will be slightly smaller and
To produce a meaningful backtrace with FRAME_POINTER enabled the kernel needs a specific function prologue: mov ip, sp stmfd sp!, {fp, ip, lr, pc} sub fp, ip, #4 To get to the required prologue gcc uses apcs and no-sched-prolog. This compiler options are not available on clang, and clang is not able to generate the required prologue. Make the FRAME_POINTER config symbol dependent on GCC. Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Stefan Agner <stefan@agner.ch> --- arch/arm/Kconfig.debug | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)