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[193.116.208.39]) by smtp.gmail.com with ESMTPSA id q23-20020a62ae17000000b006e5c464c0a9sm9121283pff.23.2024.03.19.01.00.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Mar 2024 01:00:11 -0700 (PDT) From: Nicholas Piggin To: Thomas Huth Cc: Nicholas Piggin , Laurent Vivier , Andrew Jones , Paolo Bonzini , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org Subject: [kvm-unit-tests PATCH v7 10/35] powerpc: interrupt stack backtracing Date: Tue, 19 Mar 2024 17:59:01 +1000 Message-ID: <20240319075926.2422707-11-npiggin@gmail.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20240319075926.2422707-1-npiggin@gmail.com> References: <20240319075926.2422707-1-npiggin@gmail.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Add support for backtracing across interrupt stacks, and add interrupt frame backtrace for unhandled interrupts. This requires a back-chain created from initial interrupt stack frame to the r1 value of the interrupted context. A label is added at the return location of the exception handler call, so the unwinder can recognize the initial interrupt frame. The additional cstart entry-frame is no longer required because the unwinder now looks for frame == 0 as well as address == 0. Signed-off-by: Nicholas Piggin --- lib/powerpc/processor.c | 4 +++- lib/ppc64/asm/stack.h | 3 +++ lib/ppc64/stack.c | 53 +++++++++++++++++++++++++++++++++++++++++ powerpc/Makefile.ppc64 | 1 + powerpc/cstart64.S | 15 +++--------- 5 files changed, 63 insertions(+), 13 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..e6f259de7 --- /dev/null +++ b/lib/ppc64/stack.c @@ -0,0 +1,53 @@ +#include +#include +#include + +extern char do_handle_exception_return[]; + +int arch_backtrace_frame(const void *frame, const void **return_addrs, + int max_depth, bool current_frame) +{ + 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; + + if (current_frame) + bp = __builtin_frame_address(0); + + 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] == do_handle_exception_return) { + 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; +} diff --git a/powerpc/Makefile.ppc64 b/powerpc/Makefile.ppc64 index b0ed2b104..eb682c226 100644 --- a/powerpc/Makefile.ppc64 +++ b/powerpc/Makefile.ppc64 @@ -17,6 +17,7 @@ cstart.o = $(TEST_DIR)/cstart64.o reloc.o = $(TEST_DIR)/reloc64.o OBJDIRS += lib/ppc64 +cflatobjs += lib/ppc64/stack.o # ppc64 specific tests tests = $(TEST_DIR)/spapr_vpa.elf diff --git a/powerpc/cstart64.S b/powerpc/cstart64.S index 80baabe8f..07d297f61 100644 --- a/powerpc/cstart64.S +++ b/powerpc/cstart64.S @@ -51,16 +51,6 @@ start: std r0,0(r1) std r0,16(r1) - /* - * Create entry frame of 64-bytes, same as the initial frame. A callee - * may use the caller frame to store LR, and backtrace() termination - * looks for return address == NULL, so the initial stack frame can't - * be used to call C or else it could overwrite the zeroed LR save slot - * and break backtrace termination. This frame would be unnecessary if - * backtrace looked for a zeroed frame address. - */ - stdu r1,-64(r1) - /* save DTB pointer */ std r3, 56(r1) @@ -195,6 +185,7 @@ call_handler: .endr mfsprg1 r0 std r0,GPR1(r1) + std r0,0(r1) /* Backchain from interrupt stack to regular stack */ /* lr, xer, ccr */ @@ -213,12 +204,12 @@ call_handler: subi r31, r31, 0b - start_text ld r2, (p_toc_text - start_text)(r31) - /* FIXME: build stack frame */ - /* call generic handler */ addi r3,r1,STACK_FRAME_OVERHEAD bl do_handle_exception + .global do_handle_exception_return +do_handle_exception_return: /* restore context */