[Crash-utility] [PATCH v7 12/15] ppc64: correct gdb passthroughs by implementing machdep->get_current_task_reg

From: Aditya Gupta <adityag(a)linux.ibm.com&gt; Currently, gdb passthroughs of 'bt', 'frame', 'up', 'down', 'info locals' don't work. This is due to gdb not knowing the register values to unwind the stack frames Every gdb passthrough goes through `gdb_interface`. And then, gdb expects `crash_target::fetch_registers` to give it the register values, which is dependent on `machdep->get_current_task_reg` to read the register values for specific architecture. ---------------------------- gdb passthrough (eg. "bt") | | crash -------------------------> | | | gdb_interface | | | | | | ---------------------- | fetch_registers | | | | crash_target<-------------------------+--| gdb | | --------------------------+->| | | Registers (SP,NIP, etc.)| | | | | | | | | ---------------------- | ---------------------------- Implement `machdep->get_current_task_reg` on PPC64, so that crash provides the register values to gdb to unwind stack frames properly With these changes, on powerpc, 'bt' command output in gdb mode, will look like this: gdb> bt #0 0xc0000000002a53e8 in crash_setup_regs (oldregs=<optimized out>, newregs=0xc00000000486f8d8) at ./arch/powerpc/include/asm/kexec.h:69 #1 __crash_kexec (regs=<optimized out>) at kernel/kexec_core.c:974 #2 0xc000000000168918 in panic (fmt=<optimized out>) at kernel/panic.c:358 #3 0xc000000000b735f8 in sysrq_handle_crash (key=<optimized out>) at drivers/tty/sysrq.c:155 #4 0xc000000000b742cc in __handle_sysrq (key=key@entry=99, check_mask=check_mask@entry=false) at drivers/tty/sysrq.c:602 #5 0xc000000000b7506c in write_sysrq_trigger (file=<optimized out>, buf=<optimized out>, count=2, ppos=<optimized out>) at drivers/tty/sysrq.c:1163 #6 0xc00000000069a7bc in pde_write (ppos=<optimized out>, count=<optimized out>, buf=<optimized out>, file=<optimized out>, pde=0xc000000009ed3a80) at fs/proc/inode.c:340 #7 proc_reg_write (file=<optimized out>, buf=<optimized out>, count=<optimized out>, ppos=<optimized out>) at fs/proc/inode.c:352 #8 0xc0000000005b3bbc in vfs_write (file=file@entry=0xc00000009dda7d00, buf=buf@entry=0xebcfc7c6040 <error: Cannot access memory at address 0xebcfc7c6040>, count=count@entry=2, pos=pos@entry=0xc00000000486fda0) at fs/read_write.c:582 instead of earlier output without this patch: gdb> bt #0 <unavailable> in ?? () Backtrace stopped: previous frame identical to this frame (corrupt stack?) Also, 'get_dumpfile_regs' has been introduced to get registers from multiple supported vmcore formats. Correspondingly a flag 'BT_NO_PRINT_REGS' has been introduced to tell helper functions to get registers, to not print registers with every call to backtrace in gdb. Note: This feature to support GDB unwinding doesn't support live debugging Cc: Sourabh Jain <sourabhjain(a)linux.ibm.com&gt; Cc: Hari Bathini <hbathini(a)linux.ibm.com&gt; Cc: Mahesh J Salgaonkar <mahesh(a)linux.ibm.com&gt; Cc: Naveen N. Rao <naveen.n.rao(a)linux.vnet.ibm.com&gt; Cc: Lianbo Jiang <lijiang(a)redhat.com&gt; Cc: HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab(a)nec.com&gt; Cc: Tao Liu <ltao(a)redhat.com&gt; Cc: Alexey Makhalov <alexey.makhalov(a)broadcom.com&gt; Cc: Aditya Gupta <adityag(a)linux.ibm.com&gt; Improved-by: Tao Liu <ltao(a)redhat.com&gt; Signed-off-by: Aditya Gupta <adityag(a)linux.ibm.com&gt; --- defs.h | 130 ++++++++++++++++++++++++++++++++++++ kernel.c | 33 +++++++++ ppc64.c | 174 ++++++++++++++++++++++++++++++++++++++++++++++-- unwind_x86_64.h | 4 -- 4 files changed, 330 insertions(+), 11 deletions(-) diff --git a/defs.h b/defs.h index adf45a1..ffe8acf 100644 --- a/defs.h +++ b/defs.h @@ -982,6 +982,7 @@ struct bt_info { ulong eframe_ip; ulong radix; ulong *cpumask; + bool need_free; }; #define STACK_OFFSET_TYPE(OFF) \ @@ -6130,6 +6131,7 @@ int load_module_symbols_helper(char *); void unlink_module(struct load_module *); int check_specified_module_tree(char *, char *); int is_system_call(char *, ulong); +void get_dumpfile_regs(struct bt_info*, ulong*, ulong*); void generic_dump_irq(int); void generic_get_irq_affinity(int); void generic_show_interrupts(int, ulong *); @@ -6229,6 +6231,7 @@ ulong cpu_map_addr(const char *type); #define BT_REGS_NOT_FOUND (0x4000000000000ULL) #define BT_OVERFLOW_STACK (0x8000000000000ULL) #define BT_SKIP_IDLE (0x10000000000000ULL) +#define BT_NO_PRINT_REGS (0x20000000000000ULL) #define BT_SYMBOL_OFFSET (BT_SYMBOLIC_ARGS) #define BT_REF_HEXVAL (0x1) @@ -8035,6 +8038,13 @@ extern int have_full_symbols(void); #define XEN_HYPERVISOR_ARCH #endif +#ifndef offsetof +#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) +#endif +#define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f)) +#define REG_SEQ(TYPE, MEMBER) \ + (offsetof(struct TYPE, MEMBER) / FIELD_SIZEOF(struct TYPE, MEMBER)) + /* * Register numbers must be in sync with gdb/features/i386/64bit-core.c * to make crash_target->fetch_registers() ---> machdep->get_cpu_reg() @@ -8084,6 +8094,126 @@ enum x86_64_regnum { LAST_REGNUM }; +/* + * Register numbers to make crash_target->fetch_registers() + * ---> machdep->get_current_task_reg() work properly. + * + * These register numbers and names are given according to output of + * `rs6000_register_name`, because that is what was being used by + * crash_target::fetch_registers in case of PPC64 + */ +enum ppc64_regnum { + PPC64_R0_REGNUM = 0, + PPC64_R1_REGNUM, + PPC64_R2_REGNUM, + PPC64_R3_REGNUM, + PPC64_R4_REGNUM, + PPC64_R5_REGNUM, + PPC64_R6_REGNUM, + PPC64_R7_REGNUM, + PPC64_R8_REGNUM, + PPC64_R9_REGNUM, + PPC64_R10_REGNUM, + PPC64_R11_REGNUM, + PPC64_R12_REGNUM, + PPC64_R13_REGNUM, + PPC64_R14_REGNUM, + PPC64_R15_REGNUM, + PPC64_R16_REGNUM, + PPC64_R17_REGNUM, + PPC64_R18_REGNUM, + PPC64_R19_REGNUM, + PPC64_R20_REGNUM, + PPC64_R21_REGNUM, + PPC64_R22_REGNUM, + PPC64_R23_REGNUM, + PPC64_R24_REGNUM, + PPC64_R25_REGNUM, + PPC64_R26_REGNUM, + PPC64_R27_REGNUM, + PPC64_R28_REGNUM, + PPC64_R29_REGNUM, + PPC64_R30_REGNUM, + PPC64_R31_REGNUM, + + PPC64_F0_REGNUM = 32, + PPC64_F1_REGNUM, + PPC64_F2_REGNUM, + PPC64_F3_REGNUM, + PPC64_F4_REGNUM, + PPC64_F5_REGNUM, + PPC64_F6_REGNUM, + PPC64_F7_REGNUM, + PPC64_F8_REGNUM, + PPC64_F9_REGNUM, + PPC64_F10_REGNUM, + PPC64_F11_REGNUM, + PPC64_F12_REGNUM, + PPC64_F13_REGNUM, + PPC64_F14_REGNUM, + PPC64_F15_REGNUM, + PPC64_F16_REGNUM, + PPC64_F17_REGNUM, + PPC64_F18_REGNUM, + PPC64_F19_REGNUM, + PPC64_F20_REGNUM, + PPC64_F21_REGNUM, + PPC64_F22_REGNUM, + PPC64_F23_REGNUM, + PPC64_F24_REGNUM, + PPC64_F25_REGNUM, + PPC64_F26_REGNUM, + PPC64_F27_REGNUM, + PPC64_F28_REGNUM, + PPC64_F29_REGNUM, + PPC64_F30_REGNUM, + PPC64_F31_REGNUM, + + PPC64_PC_REGNUM = 64, + PPC64_MSR_REGNUM = 65, + PPC64_CR_REGNUM = 66, + PPC64_LR_REGNUM = 67, + PPC64_CTR_REGNUM = 68, + PPC64_XER_REGNUM = 69, + PPC64_FPSCR_REGNUM = 70, + + PPC64_VR0_REGNUM = 106, + PPC64_VR1_REGNUM, + PPC64_VR2_REGNUM, + PPC64_VR3_REGNUM, + PPC64_VR4_REGNUM, + PPC64_VR5_REGNUM, + PPC64_VR6_REGNUM, + PPC64_VR7_REGNUM, + PPC64_VR8_REGNUM, + PPC64_VR9_REGNUM, + PPC64_VR10_REGNUM, + PPC64_VR11_REGNUM, + PPC64_VR12_REGNUM, + PPC64_VR13_REGNUM, + PPC64_VR14_REGNUM, + PPC64_VR15_REGNUM, + PPC64_VR16_REGNUM, + PPC64_VR17_REGNUM, + PPC64_VR18_REGNUM, + PPC64_VR19_REGNUM, + PPC64_VR20_REGNUM, + PPC64_VR21_REGNUM, + PPC64_VR22_REGNUM, + PPC64_VR23_REGNUM, + PPC64_VR24_REGNUM, + PPC64_VR25_REGNUM, + PPC64_VR26_REGNUM, + PPC64_VR27_REGNUM, + PPC64_VR28_REGNUM, + PPC64_VR29_REGNUM, + PPC64_VR30_REGNUM, + PPC64_VR31_REGNUM, + + PPC64_VSCR_REGNUM = 138, + PPC64_VRSAVE_REGNU = 139 +}; + /* crash_target.c */ extern int gdb_change_thread_context (void); diff --git a/kernel.c b/kernel.c index edfd17c..8c2e0ca 100644 --- a/kernel.c +++ b/kernel.c @@ -3535,6 +3535,39 @@ get_lkcd_regs(struct bt_info *bt, ulong *eip, ulong *esp) machdep->get_stack_frame(bt, eip, esp); } +void +get_dumpfile_regs(struct bt_info *bt, ulong *eip, ulong *esp) +{ + bt->flags |= BT_NO_PRINT_REGS; + + if (NETDUMP_DUMPFILE()) + get_netdump_regs(bt, eip, esp); + else if (KDUMP_DUMPFILE()) + get_kdump_regs(bt, eip, esp); + else if (DISKDUMP_DUMPFILE()) + get_diskdump_regs(bt, eip, esp); + else if (KVMDUMP_DUMPFILE()) + get_kvmdump_regs(bt, eip, esp); + else if (LKCD_DUMPFILE()) + get_lkcd_regs(bt, eip, esp); + else if (XENDUMP_DUMPFILE()) + get_xendump_regs(bt, eip, esp); + else if (SADUMP_DUMPFILE()) + get_sadump_regs(bt, eip, esp); + else if (VMSS_DUMPFILE()) + get_vmware_vmss_regs(bt, eip, esp); + else if (REMOTE_PAUSED()) { + if (!is_task_active(bt->task) || !get_remote_regs(bt, eip, esp)) + machdep->get_stack_frame(bt, eip, esp); + } else + machdep->get_stack_frame(bt, eip, esp); + + bt->flags &= ~BT_NO_PRINT_REGS; + + bt->instptr = *eip; + bt->stkptr = *esp; +} + /* * Store the head of the kernel module list for future use. diff --git a/ppc64.c b/ppc64.c index e8930a1..782107b 100644 --- a/ppc64.c +++ b/ppc64.c @@ -55,6 +55,8 @@ static void ppc64_set_bt_emergency_stack(enum emergency_stack_type type, static char * ppc64_check_eframe(struct ppc64_pt_regs *); static void ppc64_print_eframe(char *, struct ppc64_pt_regs *, struct bt_info *); +static int ppc64_get_current_task_reg(int regno, const char *name, int size, + void *value); static void parse_cmdline_args(void); static int ppc64_paca_percpu_offset_init(int); static void ppc64_init_cpu_info(void); @@ -73,6 +75,11 @@ static ulong pmd_page_vaddr_l4(ulong pmd); static int is_opal_context(ulong sp, ulong nip); void opalmsg(void); +struct user_regs_bitmap_struct { + struct ppc64_pt_regs ur; + ulong bitmap[32]; +}; + static int is_opal_context(ulong sp, ulong nip) { uint64_t opal_start, opal_end; @@ -704,6 +711,8 @@ ppc64_init(int when) error(FATAL, "cannot malloc hwirqstack buffer space."); } + machdep->get_current_task_reg = ppc64_get_current_task_reg; + ppc64_init_paca_info(); if (!machdep->hz) { @@ -2501,6 +2510,145 @@ ppc64_print_eframe(char *efrm_str, struct ppc64_pt_regs *regs, ppc64_print_nip_lr(regs, 1); } +static int +ppc64_get_current_task_reg(int regno, const char *name, int size, + void *value) +{ + struct bt_info bt_info, bt_setup; + struct task_context *tc; + struct user_regs_bitmap_struct *ur_bitmap; + ulong ip, sp; + bool ret = FALSE; + + /* Currently only handling registers available in ppc64_pt_regs: + * + * 0-31: r0-r31 + * 64: pc/nip + * 65: msr + * + * 67: lr + * 68: ctr + */ + switch (regno) { + case PPC64_R0_REGNUM ... PPC64_R31_REGNUM: + + case PPC64_PC_REGNUM: + case PPC64_MSR_REGNUM: + case PPC64_LR_REGNUM: + case PPC64_CTR_REGNUM: + break; + + default: + // return false if we can't get that register + if (CRASHDEBUG(1)) + error(WARNING, "unsupported register, regno=%d\n", regno); + return FALSE; + } + + tc = CURRENT_CONTEXT(); + if (!tc) + return FALSE; + BZERO(&bt_setup, sizeof(struct bt_info)); + clone_bt_info(&bt_setup, &bt_info, tc); + fill_stackbuf(&bt_info); + + // reusing the get_dumpfile_regs function to get pt regs structure + get_dumpfile_regs(&bt_info, &sp, &ip); + if (bt_info.stackbuf) + FREEBUF(bt_info.stackbuf); + ur_bitmap = (struct user_regs_bitmap_struct *)bt_info.machdep; + + if (!ur_bitmap) { + error(WARNING, "pt_regs not available for cpu %d\n", tc->processor); + return FALSE; + } + if (!bt_info.need_free) { + goto get_all; + } + + switch (regno) { + case PPC64_R0_REGNUM ... PPC64_R31_REGNUM: + if (!NUM_IN_BITMAP(ur_bitmap->bitmap, + REG_SEQ(ppc64_pt_regs, gpr[0]) + regno - PPC64_R0_REGNUM)) { + FREEBUF(ur_bitmap); + return FALSE; + } + break; + case PPC64_PC_REGNUM: + if (!NUM_IN_BITMAP(ur_bitmap->bitmap, + REG_SEQ(ppc64_pt_regs, nip))) { + FREEBUF(ur_bitmap); + return FALSE; + } + break; + case PPC64_MSR_REGNUM: + if (!NUM_IN_BITMAP(ur_bitmap->bitmap, + REG_SEQ(ppc64_pt_regs, msr))) { + FREEBUF(ur_bitmap); + return FALSE; + } + break; + case PPC64_LR_REGNUM: + if (!NUM_IN_BITMAP(ur_bitmap->bitmap, + REG_SEQ(ppc64_pt_regs, link))) { + FREEBUF(ur_bitmap); + return FALSE; + } + break; + case PPC64_CTR_REGNUM: + if (!NUM_IN_BITMAP(ur_bitmap->bitmap, + REG_SEQ(ppc64_pt_regs, ctr))) { + FREEBUF(ur_bitmap); + return FALSE; + } + break; + } + +get_all: + switch (regno) { + case PPC64_R0_REGNUM ... PPC64_R31_REGNUM: + if (size != sizeof(ur_bitmap->ur.gpr[regno])) + break; + memcpy(value, &ur_bitmap->ur.gpr[regno], size); + ret = TRUE; + break; + + case PPC64_PC_REGNUM: + if (size != sizeof(ur_bitmap->ur.nip)) + break; + memcpy(value, &ur_bitmap->ur.nip, size); + ret = TRUE; + break; + + case PPC64_MSR_REGNUM: + if (size != sizeof(ur_bitmap->ur.msr)) + break; + memcpy(value, &ur_bitmap->ur.msr, size); + ret = TRUE; + break; + + case PPC64_LR_REGNUM: + if (size != sizeof(ur_bitmap->ur.link)) + break; + memcpy(value, &ur_bitmap->ur.link, size); + ret = TRUE; + break; + + case PPC64_CTR_REGNUM: + if (size != sizeof(ur_bitmap->ur.ctr)) + break; + memcpy(value, &ur_bitmap->ur.ctr, size); + ret = TRUE; + break; + } + if (bt_info.need_free) { + FREEBUF(ur_bitmap); + bt_info.need_free = FALSE; + } + + return ret; +} + /* * For vmcore typically saved with KDump or FADump, get SP and IP values * from the saved ptregs. @@ -2613,9 +2761,11 @@ ppc64_get_dumpfile_stack_frame(struct bt_info *bt_in, ulong *nip, ulong *ksp) pt_regs = (struct ppc64_pt_regs *)bt->machdep; ur_nip = pt_regs->nip; ur_ksp = pt_regs->gpr[1]; - /* Print the collected regs for panic task. */ - ppc64_print_regs(pt_regs); - ppc64_print_nip_lr(pt_regs, 1); + if (!(bt->flags & BT_NO_PRINT_REGS)) { + /* Print the collected regs for panic task. */ + ppc64_print_regs(pt_regs); + ppc64_print_nip_lr(pt_regs, 1); + } } else if ((pc->flags & KDUMP) || ((pc->flags & DISKDUMP) && (*diskdump_flags & KDUMP_CMPRS_LOCAL))) { @@ -2779,19 +2929,29 @@ static void ppc64_get_stack_frame(struct bt_info *bt, ulong *pcp, ulong *spp) { ulong ksp, nip; - + struct user_regs_bitmap_struct *ur_bitmap; + nip = ksp = 0; - if (DUMPFILE() && is_task_active(bt->task)) + if (DUMPFILE() && is_task_active(bt->task)) { ppc64_get_dumpfile_stack_frame(bt, &nip, &ksp); - else + bt->need_free = FALSE; + } else { get_ppc64_frame(bt, &nip, &ksp); + ur_bitmap = (struct user_regs_bitmap_struct *)GETBUF(sizeof(*ur_bitmap)); + memset(ur_bitmap, 0, sizeof(*ur_bitmap)); + ur_bitmap->ur.nip = nip; + ur_bitmap->ur.gpr[1] = ksp; + SET_BIT(ur_bitmap->bitmap, REG_SEQ(ppc64_pt_regs, nip)); + SET_BIT(ur_bitmap->bitmap, REG_SEQ(ppc64_pt_regs, gpr[0]) + 1); + bt->machdep = ur_bitmap; + bt->need_free = TRUE; + } if (pcp) *pcp = nip; if (spp) *spp = ksp; - } static ulong diff --git a/unwind_x86_64.h b/unwind_x86_64.h index 850d488..d16da14 100644 --- a/unwind_x86_64.h +++ b/unwind_x86_64.h @@ -58,13 +58,9 @@ extern int unwind(struct unwind_frame_info *, int); extern void init_unwind_table(void); extern void free_unwind_table(void); -#ifndef offsetof -#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) -#endif #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)])) #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); })) -#define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f)) #define get_unaligned(ptr) (*(ptr)) //#define __get_user(x,ptr) __get_user_nocheck((x),(ptr),sizeof(*(ptr))) #define THREAD_ORDER 1 -- 2.40.1