[Crash-utility] [PATCH v2 2/2] ppc64: fix the bug eframe won't print for newer kernel

[Tao Liu <ltao@xxxxxxxxxx>]

The value of EXCP_FRAME_MARKER is outdated for kernel>=6.1.0 by kernel
commit bbd71709087a9 ("powerpc: Make stack frame marker upper case") and
commit 19c95df1277c4 ("powerpc: Reverse stack frame marker on little endian").
Also its offset is changed since kernel>=6.2.0 by kernel commit
cd52414d5a6c ("powerpc/64: ELFv2 use minimal stack frames in int and switch
frame sizes"). This patch will fix the issue by updating its values.

Before:
  crash> bt
    ...
    #8 [c00000000a327b80] system_call_exception at c000000000031a30
    #9 [c00000000a327e50] system_call_vectored_common at c00000000000d05c

After:
  crash> bt
    ...
    #8 [c00000000a327b80] system_call_exception at c000000000031a30
    #9 [c00000000a327e50] system_call_vectored_common at c00000000000d05c
    System Call Vectored [3000] exception frame:
    R0:  0000000000000004    R1:  00007fffc3345f40    R2:  0000000000100000
    R3:  0000000000000001    R4:  000000012572c620    R5:  0000000000000002
    R6:  0000000000000001    R7:  0000000000000004    R8:  0000000000000001
    ...

Signed-off-by: Tao Liu <ltao@xxxxxxxxxx>
---
 defs.h  |  6 +++++-
 ppc64.c | 37 +++++++++++++++++++++++++++----------
 2 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/defs.h b/defs.h
index abde47c..6b9b8db 100644
--- a/defs.h
+++ b/defs.h
@@ -4652,7 +4652,11 @@ struct efi_memory_desc_t {
 
 #define STACK_SWITCH_FRAME_REGS         48
 #define STACK_FRAME_OVERHEAD            112
-#define EXCP_FRAME_MARKER               0x7265677368657265
+#define EXCP_FRAME_MARKER \
+	(THIS_KERNEL_VERSION >= LINUX(6,1,0) ? \
+	  (__BYTE_ORDER == __BIG_ENDIAN ? 0x52454753 : 0x53474552) : \
+	0x7265677368657265)	/* See arch/powerpc/include/asm/ptrace.h: */
+				/* STACK_FRAME_REGS_MARKER */
 
 #define _SECTION_SIZE_BITS	24
 #define _MAX_PHYSMEM_BITS	44
diff --git a/ppc64.c b/ppc64.c
index 87f9c4c..f607060 100644
--- a/ppc64.c
+++ b/ppc64.c
@@ -2204,19 +2204,34 @@ ppc64_back_trace(struct gnu_request *req, struct bt_info *bt)
 				eframe_found = TRUE;
 			else if (STREQ(req->name, ".ret_from_except")) 
 				eframe_found = TRUE;
-		} else if ((newsp - req->sp - STACK_FRAME_OVERHEAD) >= 
-				sizeof(struct ppc64_pt_regs)) {
-			 readmem(req->sp+0x60, KVADDR, &marker, 
-				sizeof(ulong), "stack frame", FAULT_ON_ERROR);
-		        if (marker == EXCP_FRAME_MARKER) 
-				eframe_found = TRUE;
+		} else if (THIS_KERNEL_VERSION >= LINUX(6,2,0) && is_ppc64_elf_abi_v2()) {
+			if ((newsp - req->sp - STACK_SWITCH_FRAME_REGS) >=
+			    sizeof(struct ppc64_pt_regs)) {
+				readmem(req->sp+0x20, KVADDR, &marker,
+					sizeof(ulong), "stack frame",
+					FAULT_ON_ERROR);
+			}
+		} else {
+			if ((newsp - req->sp - STACK_FRAME_OVERHEAD) >=
+			    sizeof(struct ppc64_pt_regs)) {
+				readmem(req->sp+0x60, KVADDR, &marker,
+					sizeof(ulong), "stack frame",
+					FAULT_ON_ERROR);
+			}
 		}
-		if (eframe_found) {
+
+		if (eframe_found || marker == EXCP_FRAME_MARKER) {
 			char *efrm_str = NULL;
 			struct ppc64_pt_regs regs;
-			readmem(req->sp+STACK_FRAME_OVERHEAD, KVADDR, &regs,
-				sizeof(struct ppc64_pt_regs),
-				"exception frame", FAULT_ON_ERROR);
+			if (THIS_KERNEL_VERSION >= LINUX(6,2,0) && is_ppc64_elf_abi_v2()) {
+				readmem(req->sp+STACK_SWITCH_FRAME_REGS, KVADDR, &regs,
+					sizeof(struct ppc64_pt_regs),
+					"exception frame", FAULT_ON_ERROR);
+			} else {
+				readmem(req->sp+STACK_FRAME_OVERHEAD, KVADDR, &regs,
+					sizeof(struct ppc64_pt_regs),
+					"exception frame", FAULT_ON_ERROR);
+			}
 
 			efrm_str = ppc64_check_eframe(&regs);
 			if (efrm_str) {
@@ -2427,6 +2442,8 @@ ppc64_check_eframe(struct ppc64_pt_regs *regs)
 		return("Denormalisation");
 	case 0x1700:    
 		return("Altivec Assist");
+	case 0x3000:
+		return("System Call Vectored");
 	}
 	
 	/* No exception frame exists */
-- 
2.46.2
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