On Sat, Jun 17, 2023 at 01:49:27AM +0000, Nadav Amit wrote:
> From: Nadav Amit <namit@xxxxxxxxxx>
>
> Enable frame pointers for arm64 and perform stack unwinding based on
> arm64 convention.
>
> Signed-off-by: Nadav Amit <namit@xxxxxxxxxx>
> ---
> arm/Makefile.arm | 3 ---
> arm/Makefile.arm64 | 1 +
> arm/Makefile.common | 3 +++
> lib/arm64/asm/stack.h | 3 +++
> lib/arm64/stack.c | 37 +++++++++++++++++++++++++++++++++++++
> 5 files changed, 44 insertions(+), 3 deletions(-)
> create mode 100644 lib/arm64/stack.c
>
> diff --git a/arm/Makefile.arm b/arm/Makefile.arm
> index 2ce00f5..7fd39f3 100644
> --- a/arm/Makefile.arm
> +++ b/arm/Makefile.arm
> @@ -11,9 +11,6 @@ ifeq ($(CONFIG_EFI),y)
> $(error Cannot build arm32 tests as EFI apps)
> endif
>
> -# stack.o relies on frame pointers.
> -KEEP_FRAME_POINTER := y
> -
> CFLAGS += $(machine)
> CFLAGS += -mcpu=$(PROCESSOR)
> CFLAGS += -mno-unaligned-access
> diff --git a/arm/Makefile.arm64 b/arm/Makefile.arm64
> index eada7f9..60385e2 100644
> --- a/arm/Makefile.arm64
> +++ b/arm/Makefile.arm64
> @@ -21,6 +21,7 @@ define arch_elf_check =
> endef
>
> cstart.o = $(TEST_DIR)/cstart64.o
> +cflatobjs += lib/arm64/stack.o
> cflatobjs += lib/arm64/processor.o
> cflatobjs += lib/arm64/spinlock.o
> cflatobjs += lib/arm64/gic-v3-its.o lib/arm64/gic-v3-its-cmd.o
> diff --git a/arm/Makefile.common b/arm/Makefile.common
> index f904702..7fecfb3 100644
> --- a/arm/Makefile.common
> +++ b/arm/Makefile.common
> @@ -22,6 +22,9 @@ $(TEST_DIR)/sieve.elf: AUXFLAGS = 0x1
> ##################################################################
> AUXFLAGS ?= 0x0
>
> +# stack.o relies on frame pointers.
> +KEEP_FRAME_POINTER := y
> +
> CFLAGS += -std=gnu99
> CFLAGS += -ffreestanding
> CFLAGS += -O2
> diff --git a/lib/arm64/asm/stack.h b/lib/arm64/asm/stack.h
> index d000624..be486cf 100644
> --- a/lib/arm64/asm/stack.h
> +++ b/lib/arm64/asm/stack.h
> @@ -5,4 +5,7 @@
> #error Do not directly include <asm/stack.h>. Just use <stack.h>.
> #endif
>
> +#define HAVE_ARCH_BACKTRACE_FRAME
> +#define HAVE_ARCH_BACKTRACE
> +
> #endif
> diff --git a/lib/arm64/stack.c b/lib/arm64/stack.c
> new file mode 100644
> index 0000000..1e2568a
> --- /dev/null
> +++ b/lib/arm64/stack.c
> @@ -0,0 +1,37 @@
> +/*
> + * backtrace support (this is a modified lib/x86/stack.c)
> + *
> + * This work is licensed under the terms of the GNU LGPL, version 2.
> + */
> +#include <libcflat.h>
> +#include <stack.h>
> +
> +extern char vector_stub_start, vector_stub_end;
These aren't used until the next patch.
> +
> +int backtrace_frame(const void *frame, const void **return_addrs, int max_depth) {
'{' should be on its own line. I usually try to run the kernel's
checkpatch since we use the same style (except we're even more forgiving
for long lines).
> + const void *fp = frame;
> + void *lr;
> + int depth;
> +
> + /*
> + * ARM64 stack grows down. fp points to the previous fp on the stack,
> + * and lr is just above it
> + */
> + for (depth = 0; fp && depth < max_depth; ++depth) {
> +
> + asm volatile ("ldp %0, %1, [%2]"
> + : "=r" (fp), "=r" (lr)
> + : "r" (fp)
> + : );
> +
> + return_addrs[depth] = lr;
> + }
> +
> + return depth;
> +}
> +
> +int backtrace(const void **return_addrs, int max_depth)
> +{
> + return backtrace_frame(__builtin_frame_address(0),
> + return_addrs, max_depth);
> +}
> --
> 2.34.1
>
Thanks,
drew
