diff mbox series

[v3,3/3] kgdb: Add command linux.vmcoreinfo to kgdb

Message ID 20250113172936.1434532-5-tjarlama@gmail.com
State New
Headers show
Series Add a new command in kgdb for vmcoreinfo | expand

Commit Message

Amal Raj T Jan. 13, 2025, 5:29 p.m. UTC 
From: Amal Raj T <amalrajt@meta.com>

Add a new query `linux.vmcoreinfo` to kgdb that returns
vmcoreinfo to the client using the mem2ebin encoding.
Maximum size of output buffer is set to 2x the maximum
size of VMCOREINFO_BYTES (kgdb_mem2ebin() requires 1x
for the temporary copy plus another 1x (max) for the
escaped data).

Link: https://github.com/osandov/drgn/wiki/GDB-Remote-Protocol-proposal:-linux.vmcoreinfo-query-packet
---
 kernel/debug/gdbstub.c | 18 ++++++++++++++----
 lib/Kconfig.kgdb       |  1 +
 2 files changed, 15 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c
index f88e21d5502a..f2c80bd368e2 100644
--- a/kernel/debug/gdbstub.c
+++ b/kernel/debug/gdbstub.c
@@ -30,20 +30,21 @@ 
 #include <linux/kgdb.h>
 #include <linux/kdb.h>
 #include <linux/serial_core.h>
+#include <linux/string.h>
 #include <linux/reboot.h>
 #include <linux/uaccess.h>
 #include <asm/cacheflush.h>
 #include <linux/unaligned.h>
+#include <linux/vmcore_info.h>
 #include "debug_core.h"
 
 #define KGDB_MAX_THREAD_QUERY 17
 
 /* Our I/O buffers. */
 static char remcom_in_buffer[BUFMAX];
-static char remcom_out_buffer[BUFMAX];
+static char remcom_out_buffer[MAX(VMCOREINFO_BYTES * 2, BUFMAX)];
 static int gdbstub_use_prev_in_buf;
 static int gdbstub_prev_in_buf_pos;
-
 /* Storage for the registers, in GDB format. */
 static unsigned long gdb_regs[(NUMREGBYTES + sizeof(unsigned long) - 1) /
 			      sizeof(unsigned long)];
@@ -292,8 +293,8 @@  char *kgdb_mem2ebin(char *mem, char *buf, int count)
 		} else {
 			*buf++ = c;
 		}
-		count -= 1;
-		tmp += 1;
+		count--;
+		tmp++;
 	}
 
 	return buf;
@@ -777,6 +778,15 @@  static void gdb_cmd_query(struct kgdb_state *ks)
 		*(--ptr) = '\0';
 		break;
 
+	case 'l':
+		if (strncmp(remcom_in_buffer + 1, "linux.vmcoreinfo", 17) ==
+		    0) {
+			remcom_out_buffer[0] = 'Q';
+			kgdb_mem2ebin(vmcoreinfo_data, remcom_out_buffer + 1,
+				      vmcoreinfo_size);
+		}
+		break;
+
 	case 'C':
 		/* Current thread id */
 		strcpy(remcom_out_buffer, "QC");
diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb
index 537e1b3f5734..012529eee79e 100644
--- a/lib/Kconfig.kgdb
+++ b/lib/Kconfig.kgdb
@@ -12,6 +12,7 @@  menuconfig KGDB
 	bool "KGDB: kernel debugger"
 	depends on HAVE_ARCH_KGDB
 	depends on DEBUG_KERNEL
+	select VMCORE_INFO
 	help
 	  If you say Y here, it will be possible to remotely debug the
 	  kernel using gdb.  It is recommended but not required, that