3:33 p.m.
The Problem:
============
Currently crash is unable to show function arguments and local variables, as
gdb can do. And functionality for moving between frames ('up'/'down') is
not
working in crash.
Crash has 'gdb passthroughs' for things gdb can do, but the gdb passthroughs
'bt', 'frame', 'info locals', 'up', 'down' are not
working either, due to
gdb not getting the register values from `crash_target::fetch_registers`,
which then uses `machdep->get_cpu_reg`, which is not implemented for PPC64
Proposed Solution:
==================
Fix the gdb passthroughs by implementing "machdep->get_cpu_reg" for PPC64.
This way, "gdb mode in crash" will support this feature for both ELF and
kdump-compressed vmcore formats, while "gdb" would only have supported ELF
format
Implications on Architectures:
====================================
No architecture other than PPC64 has been affected, other than in case of
'frame' command
As mentioned in patch #2, since frame will not be prohibited, so it will print:
crash> frame
#0 <unavailable> in ?? ()
Instead of before prohibited message:
crash> frame
crash: prohibited gdb command: frame
On PPC64, the default mode ("crash mode") will not have ANY OTHER changes,
other than 'frame' as mentioned above.
Major change will be in 'gdb mode' on PPC64, that it will print the frames, and
local variables, instead of failing with errors showing no frame, or showing
that couldn't get PC
Testing:
========
Git tree with this patch series applied:
https://github.com/adi-g15-ibm/crash/tree/stack-unwind-rfc2
To test gdb passthroughs:
crash> set gdb on
gdb> thread 3 # or any other thread number to change context in gdb
gdb> bt
gdb> frame
gdb> up
gdb> down
gdb> info locals
Known Issues:
=============
1. In gdb mode, 'info threads' might hang for few seconds, and print only 2
threads
2. In gdb mode, 'bt' might fail to show backtrace in few vmcores collected
from older kernels. This is a known issue due to register mismatch, and
its fix has been merged upstream:
Commit: https://github.com/torvalds/linux/commit/b684c09f09e7a6af3794d4233ef78581...
TODO:
=====
1. Introduce automatic thread selection in gdb mode, to select the crashing
thread in gdb, eliminating the need to manually run "thread <id>"
after
switching to gdb mode.
Changelog:
==========
RFC V2:
- removed patch implementing 'frame', 'up', 'down' in crash
- updated the cover letter by removing the mention of those commands other
than the respective gdb passthrough
Aditya Gupta (4):
add generic get_dumpfile_regs to read registers
ppc64: fix gdb passthrough by implementing machdep->get_cpu_reg
remove 'frame' from prohibited commands list
make cpu context change transparent to crash/gdb
defs.h | 125 ++++++++++++++++++++++++++++++++++++++++++++++++
gdb-10.2.patch | 28 +++++++++++
gdb_interface.c | 2 +-
kernel.c | 33 +++++++++++++
ppc64.c | 105 ++++++++++++++++++++++++++++++++++++++--
tools.c | 12 +++--
6 files changed, 298 insertions(+), 7 deletions(-)
--
2.41.0
3:33 p.m.
New subject: [RFC PATCH v2 1/4] add generic get_dumpfile_regs to read registers
Currently the logic for reading registers from each type of dumpfile is
separated into different functions depending on the vmcore type.
This causes duplication of code when any architecture wants to support
reading registers from multiple vmcore types, by having a if-else ladder
calling respective function to read registers, depending on vmcore type.
Instead, implement 'get_dumpfile_regs' to handle this and call the
appropriate function for reading the registers, based on vmcore type and
architecture. It is architecture agnostic, and can be used by all
supported architectures and all supported vmcores
Also, on PPC64, 'ppc64_get_dumpfile_stack_frame' also prints the registers,
but now 'ppc64_get_dumpfile_stack_frame' gets called more frequently and
printed registers everytime 'bt' is run in gdb mode. 'BT_NO_PRINT_REGS'
flag has been introduced, so it can be set in 'bt->flags' by the caller to
convey that we don't want the registers to be printed
'get_dumpfile_regs' is used in later patches crash to fix gdb passthrough by
providing it register values
Signed-off-by: Aditya Gupta <adityag(a)linux.ibm.com>
---
defs.h | 2 ++
kernel.c | 33 +++++++++++++++++++++++++++++++++
ppc64.c | 8 +++++---
3 files changed, 40 insertions(+), 3 deletions(-)
diff --git a/defs.h b/defs.h
index 358f365585cf..b6f213120975 100644
--- a/defs.h
+++ b/defs.h
@@ -6021,6 +6021,7 @@ 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 *);
@@ -6117,6 +6118,7 @@ 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)
diff --git a/kernel.c b/kernel.c
index 2114700eecc8..e6920e241c4e 100644
--- a/kernel.c
+++ b/kernel.c
@@ -3514,6 +3514,39 @@ 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 fc34006f4863..7622f68289e7 100644
--- a/ppc64.c
+++ b/ppc64.c
@@ -2584,9 +2584,11 @@ 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))) {
--
2.41.0
3:33 p.m.
New subject: [RFC PATCH v2 2/4] ppc64: fix gdb passthrough by implementing machdep->get_cpu_reg
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_cpu_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_cpu_reg` on PPC64, so that crash provides the
register values to gdb to unwind stack frames properly
Also, with the goal to preserve the behaviour of gdb passthroughs in
default mode, a hook 'machdep->gdb_mode_hook' has been introduced, which
will get executed everytime when "set gdb on", and "set gdb off" are
run,
and can be used by any architecture.
This hook has been used on PPC64 such that, `machdep->get_cpu_reg` is only
set on "set gdb on", and set to NULL in default mode (or on "set gdb
off"),
so that behaviour of gdb passthroughs in default mode stays the same.
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?)
Signed-off-by: Aditya Gupta <adityag(a)linux.ibm.com>
---
defs.h | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
ppc64.c | 100 +++++++++++++++++++++++++++++++++++++++++++++
tools.c | 12 ++++--
3 files changed, 232 insertions(+), 3 deletions(-)
diff --git a/defs.h b/defs.h
index b6f213120975..798a49e7ec41 100644
--- a/defs.h
+++ b/defs.h
@@ -1074,6 +1074,7 @@ struct machdep_table {
void (*show_interrupts)(int, ulong *);
int (*is_page_ptr)(ulong, physaddr_t *);
int (*get_cpu_reg)(int, int, const char *, int, void *);
+ void (*gdb_mode_hook)(int gdb_mode_enabled);
};
/*
@@ -6660,6 +6661,8 @@ struct machine_specific {
void ppc64_init(int);
void ppc64_dump_machdep_table(ulong);
+int ppc64_get_cpu_reg(int cpu, int regno, const char *name, int size,
+ void *value);
#define display_idt_table() \
error(FATAL, "-d option is not applicable to PowerPC architecture\n")
#define KSYMS_START (0x1)
@@ -7839,4 +7842,124 @@ enum x86_64_regnum {
LAST_REGNUM
};
+/*
+ * Register numbers to make crash_target->fetch_registers()
+ * ---> machdep->get_cpu_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_renum {
+ 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
+};
+
#endif /* !GDB_COMMON */
diff --git a/ppc64.c b/ppc64.c
index 7622f68289e7..61ff47c2c8d9 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 *);
+int ppc64_get_cpu_reg(int cpu, 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);
@@ -63,6 +65,7 @@ static void ppc64_clear_machdep_cache(void);
static void ppc64_init_paca_info(void);
static void ppc64_vmemmap_init(void);
static int ppc64_get_kvaddr_ranges(struct vaddr_range *);
+static void ppc64_gdb_mode_hook(int gdb_mode_enabled);
static uint get_ptetype(ulong pte);
static int is_hugepage(ulong pte);
static int is_hugepd(ulong pte);
@@ -140,6 +143,15 @@ static inline int is_hugepd(ulong pte)
}
}
+static void ppc64_gdb_mode_hook(int gdb_mode_enabled)
+{
+ if (gdb_mode_enabled) {
+ machdep->get_cpu_reg = ppc64_get_cpu_reg;
+ } else {
+ machdep->get_cpu_reg = NULL;
+ }
+}
+
static inline uint get_ptetype(ulong pte)
{
uint pte_type = 0; /* 0: regular entry; 1: huge pte; 2: huge pd */
@@ -694,6 +706,8 @@ ppc64_init(int when)
error(FATAL, "cannot malloc hwirqstack buffer space.");
}
+ machdep->gdb_mode_hook = ppc64_gdb_mode_hook;
+
ppc64_init_paca_info();
if (!machdep->hz) {
@@ -2472,6 +2486,92 @@ ppc64_print_eframe(char *efrm_str, struct ppc64_pt_regs *regs,
ppc64_print_nip_lr(regs, 1);
}
+int
+ppc64_get_cpu_reg(int cpu, int regno, const char *name, int size,
+ void *value)
+{
+ struct bt_info bt_info, bt_setup;
+ struct task_context *tc;
+ struct ppc64_pt_regs *pt_regs;
+ ulong ip, sp;
+
+ /* Currently only handling registers available in 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
+ return FALSE;
+ }
+
+ /* FIXME: Always setting the context to CURRENT_CONTEXT irrespective of whicher
+ * thread we switched to, in gdb
+ */
+ tc = CURRENT_CONTEXT();
+ 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);
+ pt_regs = (struct ppc64_pt_regs *)bt_info.machdep;
+
+ switch (regno) {
+ case PPC64_R0_REGNUM ... PPC64_R31_REGNUM:
+ if (size != sizeof(pt_regs->gpr[regno]))
+ return FALSE; // size mismatch
+
+ memcpy(value, &pt_regs->gpr[regno], size);
+ return TRUE;
+
+ case PPC64_PC_REGNUM:
+ if (size != sizeof(pt_regs->nip))
+ return FALSE; // size mismatch
+
+ memcpy(value, &pt_regs->nip, size);
+ return TRUE;
+
+ case PPC64_MSR_REGNUM:
+ if (size != sizeof(pt_regs->msr))
+ return FALSE; // size mismatch
+
+ memcpy(value, &pt_regs->msr, size);
+ return TRUE;
+
+ case PPC64_LR_REGNUM:
+ if (size != sizeof(pt_regs->link))
+ return FALSE; // size mismatch
+
+ memcpy(value, &pt_regs->link, size);
+ return TRUE;
+
+ case PPC64_CTR_REGNUM:
+ if (size != sizeof(pt_regs->ctr))
+ return FALSE; // size mismatch
+
+ memcpy(value, &pt_regs->ctr, size);
+ return TRUE;
+ }
+
+ printf("error: %s: statement after switch case should be unreachable"
+ , __func__);
+ return FALSE;
+}
+
/*
* For vmcore typically saved with KDump or FADump, get SP and IP values
* from the saved ptregs.
diff --git a/tools.c b/tools.c
index 0f2db108838a..b8081f350ae9 100644
--- a/tools.c
+++ b/tools.c
@@ -2075,12 +2075,18 @@ cmd_set(void)
if (!runtime)
defer();
else if (STREQ(args[optind], "on")) {
- if (pc->flags & MINIMAL_MODE)
+ if (pc->flags & MINIMAL_MODE) {
goto invalid_set_command;
- else
+ } else {
pc->flags2 |= GDB_CMD_MODE;
- } else if (STREQ(args[optind], "off"))
+ if (machdep->gdb_mode_hook)
+ machdep->gdb_mode_hook(1);
+ }
+ } else if (STREQ(args[optind], "off")) {
pc->flags2 &= ~GDB_CMD_MODE;
+ if (machdep->gdb_mode_hook)
+ machdep->gdb_mode_hook(0);
+ }
else if (IS_A_NUMBER(args[optind])) {
value = stol(args[optind],
FAULT_ON_ERROR, NULL);
--
2.41.0
3:33 p.m.
New subject: [RFC PATCH v2 3/4] remove 'frame' from prohibited commands list
Currently, 'frame' is prohibited on every architecture, even in gdb mode.
Since the passthrough is working on few architectures (eg. ppc64, and
vmss x86_64), so remove it from prohibited list, so that 'frame' command
can be used
This has an implication on all architectures, that 'frame' now outputs
this in default mode:
```
crash> frame
#0 <unavailable> in ?? ()
```
instead of the before prohibited message
```
crash> frame
crash: prohibited gdb command: frame
```
Though, 'frame' should work in gdb mode for architectures that implement
'machdep->get_cpu_reg'
Signed-off-by: Aditya Gupta <adityag(a)linux.ibm.com>
---
gdb_interface.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gdb_interface.c b/gdb_interface.c
index b14319c66147..8f99a0d7fd54 100644
--- a/gdb_interface.c
+++ b/gdb_interface.c
@@ -711,7 +711,7 @@ static char *prohibited_list[] = {
"watch", "rwatch", "awatch", "attach",
"continue", "c", "fg", "detach",
"finish", "handle", "interrupt", "jump",
"kill", "next", "nexti",
"signal", "step", "s", "stepi",
"target", "until", "delete",
- "clear", "disable", "enable", "condition",
"ignore", "frame", "catch",
+ "clear", "disable", "enable", "condition",
"ignore", "catch",
"tcatch", "return", "file", "exec-file",
"core-file", "symbol-file",
"load", "si", "ni", "shell", "sy",
NULL /* must be last */
--
2.41.0
3:33 p.m.
New subject: [RFC PATCH v2 4/4] make cpu context change transparent to crash/gdb
Currently the gdb passthrough get back to `crash_target::fetch_registers`
to get register values, which depends on the current context in crash.
So even though `thread` command run in gdb mode or as a passthrough,
it did not change the cpu in crash, hence no context change in crash,
thereby getting register values with respect to wrong thread/cpu
Even if in gdb mode, `thread <thread_num>` command is run, it does not
change the cpu in the crash context.
Modify the current cpu in crash, when 'thread <thread_num' is run in gdb
mode or as gdb passthrough.
Signed-off-by: Aditya Gupta <adityag(a)linux.ibm.com>
---
gdb-10.2.patch | 28 ++++++++++++++++++++++++++++
ppc64.c | 3 ---
2 files changed, 28 insertions(+), 3 deletions(-)
diff --git a/gdb-10.2.patch b/gdb-10.2.patch
index 16228b1dbf73..89826e5fc7e0 100644
--- a/gdb-10.2.patch
+++ b/gdb-10.2.patch
@@ -10,6 +10,7 @@
tar xvzmf gdb-10.2.tar.gz \
gdb-10.2/gdb/symtab.c \
+ gdb-10.2/gdb/thread.c \
gdb-10.2/gdb/printcmd.c \
gdb-10.2/gdb/symfile.c \
gdb-10.2/gdb/Makefile.in \
@@ -483,7 +484,34 @@ exit 0
+#endif
return best_pst;
}
+--- gdb-10.2/gdb/thread.c.orig
++++ gdb-10.2/gdb/thread.c
+@@ -58,6 +58,11 @@ static int highest_thread_num;
+ /* The current/selected thread. */
+ static thread_info *current_thread_;
++#ifdef CRASH_MERGE
++/* Function to set cpu, defined by crash-utility */
++extern "C" void set_cpu (int);
++#endif
++
+ /* RAII type used to increase / decrease the refcount of each thread
+ in a given list of threads. */
+
+@@ -1896,7 +1901,12 @@ thread_command (const char *tidstr, int from_tty)
+ {
+ ptid_t previous_ptid = inferior_ptid;
+
+- thread_select (tidstr, parse_thread_id (tidstr, NULL));
++ struct thread_info* thread_id = parse_thread_id (tidstr, NULL);
++ thread_select (tidstr, thread_id);
++
++#ifdef CRASH_MERGE
++ set_cpu(thread_id->ptid.tid());
++#endif
+
+ /* Print if the thread has not changed, otherwise an event will
+ be sent. */
--- gdb-10.2/gdb/symfile.c.orig
+++ gdb-10.2/gdb/symfile.c
@@ -652,7 +652,26 @@ default_symfile_offsets (struct objfile *objfile,
diff --git a/ppc64.c b/ppc64.c
index 61ff47c2c8d9..51b2a1ace422 100644
--- a/ppc64.c
+++ b/ppc64.c
@@ -2518,9 +2518,6 @@ ppc64_get_cpu_reg(int cpu, int regno, const char *name, int size,
return FALSE;
}
- /* FIXME: Always setting the context to CURRENT_CONTEXT irrespective of whicher
- * thread we switched to, in gdb
- */
tc = CURRENT_CONTEXT();
BZERO(&bt_setup, sizeof(struct bt_info));
clone_bt_info(&bt_setup, &bt_info, tc);
--
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Aditya Gupta