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From: Andrew Jones To: Nicholas Piggin Subject: Re: [kvm-unit-tests PATCH 04/32] powerpc: interrupt stack backtracing Message-ID: <20240228-9b32ddf7f58dc8f75b24e33c@orel> References: <20240226101218.1472843-1-npiggin@gmail.com> <20240226101218.1472843-5-npiggin@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240226101218.1472843-5-npiggin@gmail.com> X-Migadu-Flow: FLOW_OUT X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , Thomas Huth , kvm@vger.kernel.org, Joel Stanley , Paolo Bonzini , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, Feb 26, 2024 at 08:11:50PM +1000, Nicholas Piggin wrote: > Add support for backtracing across interrupt stacks, and > add interrupt frame backtrace for unhandled interrupts. > > Signed-off-by: Nicholas Piggin > --- > lib/powerpc/processor.c | 4 ++- > lib/ppc64/asm/stack.h | 3 +++ > lib/ppc64/stack.c | 55 +++++++++++++++++++++++++++++++++++++++++ > powerpc/Makefile.ppc64 | 1 + > powerpc/cstart64.S | 7 ++++-- > 5 files changed, 67 insertions(+), 3 deletions(-) > create mode 100644 lib/ppc64/stack.c > > diff --git a/lib/powerpc/processor.c b/lib/powerpc/processor.c > index ad0d95666..114584024 100644 > --- a/lib/powerpc/processor.c > +++ b/lib/powerpc/processor.c > @@ -51,7 +51,9 @@ void do_handle_exception(struct pt_regs *regs) > return; > } > > - printf("unhandled cpu exception %#lx at NIA:0x%016lx MSR:0x%016lx\n", regs->trap, regs->nip, regs->msr); > + printf("Unhandled cpu exception %#lx at NIA:0x%016lx MSR:0x%016lx\n", > + regs->trap, regs->nip, regs->msr); > + dump_frame_stack((void *)regs->nip, (void *)regs->gpr[1]); > abort(); > } > > diff --git a/lib/ppc64/asm/stack.h b/lib/ppc64/asm/stack.h > index 9734bbb8f..94fd1021c 100644 > --- a/lib/ppc64/asm/stack.h > +++ b/lib/ppc64/asm/stack.h > @@ -5,4 +5,7 @@ > #error Do not directly include . Just use . > #endif > > +#define HAVE_ARCH_BACKTRACE > +#define HAVE_ARCH_BACKTRACE_FRAME > + > #endif > diff --git a/lib/ppc64/stack.c b/lib/ppc64/stack.c > new file mode 100644 > index 000000000..fcb7fa860 > --- /dev/null > +++ b/lib/ppc64/stack.c > @@ -0,0 +1,55 @@ > +#include > +#include > +#include > + > +extern char exception_stack_marker[]; > + > +int backtrace_frame(const void *frame, const void **return_addrs, int max_depth) > +{ > + static int walking; > + int depth = 0; > + const unsigned long *bp = (unsigned long *)frame; > + void *return_addr; > + > + asm volatile("" ::: "lr"); /* Force it to save LR */ > + > + if (walking) { > + printf("RECURSIVE STACK WALK!!!\n"); > + return 0; > + } > + walking = 1; > + > + bp = (unsigned long *)bp[0]; > + return_addr = (void *)bp[2]; > + > + for (depth = 0; bp && depth < max_depth; depth++) { > + return_addrs[depth] = return_addr; > + if (return_addrs[depth] == 0) > + break; > + if (return_addrs[depth] == exception_stack_marker) { > + struct pt_regs *regs; > + > + regs = (void *)bp + STACK_FRAME_OVERHEAD; > + bp = (unsigned long *)bp[0]; > + /* Represent interrupt frame with vector number */ > + return_addr = (void *)regs->trap; > + if (depth + 1 < max_depth) { > + depth++; > + return_addrs[depth] = return_addr; > + return_addr = (void *)regs->nip; > + } > + } else { > + bp = (unsigned long *)bp[0]; > + return_addr = (void *)bp[2]; > + } > + } > + > + walking = 0; > + return depth; > +} > + > +int backtrace(const void **return_addrs, int max_depth) > +{ > + return backtrace_frame(__builtin_frame_address(0), return_addrs, > + max_depth); > +} I'm about to post a series which has a couple treewide tracing changes in them. Depending on which series goes first the other will need to accommodate. Thanks, drew