Re: [Openocd-development] PATCH: XScale vector table handling / Linux kernel debugging
Committed. Thanks! -- Øyvind Harboe Embedded software and hardware consulting services http://www.zylin.com ___ Openocd-development mailing list Openocd-development@lists.berlios.de https://lists.berlios.de/mailman/listinfo/openocd-development
Re: [Openocd-development] PATCH: XScale vector table handling / Linux kernel debugging
David Brownell wrote:
That one example shouldn't go *between* the @deffn blocks ...
it's part of the preceding @deffn, giving the bit semantics,
not a free-standing chunk of text.
I must admit I do know nothing about texinfo.
How about this version?
cu
Michael
Index: src/target/xscale.c
===
--- src/target/xscale.c (revision 2606)
+++ src/target/xscale.c (working copy)
@@ -5,6 +5,9 @@
* Copyright (C) 2007,2008 Ãyvind Harboe *
* oyvind.har...@zylin.com *
* *
+ * Copyright (C) 2009 Michael Schwingen *
+ * mich...@schwingen.org *
+ * *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
@@ -3384,6 +3387,65 @@
}
+int xscale_handle_vector_table_command(command_context_t *cmd_ctx, char *cmd, char **args, int argc)
+{
+ target_t *target = get_current_target(cmd_ctx);
+ armv4_5_common_t *armv4_5;
+ xscale_common_t *xscale;
+ int err = 0;
+
+ if (xscale_get_arch_pointers(target, armv4_5, xscale) != ERROR_OK)
+ {
+ return ERROR_OK;
+ }
+
+ if (argc == 0) /* print current settings */
+ {
+ int idx;
+
+ command_print(cmd_ctx, active user-set static vectors:);
+ for (idx = 1; idx 8; idx++)
+ if (xscale-static_low_vectors_set (1 idx))
+command_print(cmd_ctx, low %d: 0x%x, idx, xscale-static_low_vectors[idx]);
+ for (idx = 1; idx 8; idx++)
+ if (xscale-static_high_vectors_set (1 idx))
+command_print(cmd_ctx, high %d: 0x%x, idx, xscale-static_high_vectors[idx]);
+ return ERROR_OK;
+ }
+
+ if (argc != 3)
+ err = 1;
+ else
+ {
+ int idx;
+ uint32_t vec;
+ idx = strtoul(args[1], NULL, 0);
+ vec = strtoul(args[2], NULL, 0);
+
+ if (idx 1 || idx = 8)
+ err = 1;
+
+ if (!err strcmp(args[0], low) == 0)
+ {
+ xscale-static_low_vectors_set |= (1idx);
+ xscale-static_low_vectors[idx] = vec;
+ }
+ else if (!err (strcmp(args[0], high) == 0))
+ {
+ xscale-static_high_vectors_set |= (1idx);
+ xscale-static_high_vectors[idx] = vec;
+ }
+ else
+ err = 1;
+ }
+
+ if (err)
+ command_print(cmd_ctx, usage: xscale vector_table high|low index code);
+
+ return ERROR_OK;
+}
+
+
int xscale_handle_trace_buffer_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
{
target_t *target = get_current_target(cmd_ctx);
@@ -3692,6 +3754,7 @@
register_command(cmd_ctx, xscale_cmd, dcache, xscale_handle_idcache_command, COMMAND_EXEC, ['enable'|'disable'] the DCache);
register_command(cmd_ctx, xscale_cmd, vector_catch, xscale_handle_vector_catch_command, COMMAND_EXEC, mask of vectors that should be catched);
+ register_command(cmd_ctx, xscale_cmd, vector_table, xscale_handle_vector_table_command, COMMAND_EXEC, high|low index code set static code for exception handler entry);
register_command(cmd_ctx, xscale_cmd, trace_buffer, xscale_handle_trace_buffer_command, COMMAND_EXEC, enable | disable ['fill' [n]|'wrap']);
Index: doc/openocd.texi
===
--- doc/openocd.texi (revision 2606)
+++ doc/openocd.texi (working copy)
@@ -4877,6 +4877,52 @@
@subsection XScale specific commands
@cindex XScale
+Some notes about the debug implementation on the XScale CPUs:
+
+The XScale CPU provides a special debug-only mini-instruction cache
+(mini-IC) in which exception vectors and target-resident debug handler
+code are placed by OpenOCD. In order to get access to the CPU, OpenOCD
+must point vector 0 (the reset vector) to the entry of the debug
+handler. However, this means that the complete first cacheline in the
+mini-IC is marked valid, which makes the CPU fetch all exception
+handlers from the mini-IC, ignoring the code in RAM.
+
+OpenOCD currently does not sync the mini-IC entries with the RAM
+contents (which would fail anyway while the target is running), so
+the user must provide appropriate values using the @code{xscale
+vector_table} command.
+
+It is recommended to place a pc-relative indirect branch in the vector
+table, and put the branch destination somewhere in memory. Doing so
+makes sure the code in the vector table stays constant regardless of
+code layout in memory:
+...@example
+_vectors:
+ldr pc,[pc,#0x100-8]
+ldr pc,[pc,#0x100-8]
+ldr pc,[pc,#0x100-8]
+ldr pc,[pc,#0x100-8]
+ldr pc,[pc,#0x100-8]
+ldr pc,[pc,#0x100-8]
+ldr pc,[pc,#0x100-8]
+ldr pc,[pc,#0x100-8]
+.org 0x100
+.long real_reset_vector
+.long
Re: [Openocd-development] PATCH: XScale vector table handling / Linux kernel debugging
On Tuesday 25 August 2009, Michael Schwingen wrote: That one example shouldn't go *between* the @deffn blocks ... it's part of the preceding @deffn, giving the bit semantics, not a free-standing chunk of text. I must admit I do know nothing about texinfo. How about this version? OK; thanks! ___ Openocd-development mailing list Openocd-development@lists.berlios.de https://lists.berlios.de/mailman/listinfo/openocd-development
[Openocd-development] PATCH: XScale vector table handling / Linux kernel debugging
Hi,
it seems the XScale vector table handling code in OpenOCD is only partially
implemented: the code to use user-provided vectors is there, but there is no
way to set these variables, and also no code that syncs the cached vectors
with the RAM contents.
The attached patch adds a xscale vector_table command that allows to set
the values that are written in the mini-IC (plus documentation updates that
describe why this is needed).
Using the correct values, I can now start and debug a Linux kernel on my
IXP425 board from openocd - this would before crash after uncompressing
kernel, because the cached exception vectors were completely off.
This is only tested on big-endian IXP42x, but even if it does not work on
other CPUs, it should not break any existing functionality.
cu
Michael
Index: src/target/xscale.c
===
--- src/target/xscale.c (revision 2606)
+++ src/target/xscale.c (working copy)
@@ -5,6 +5,9 @@
* Copyright (C) 2007,2008 Ãyvind Harboe *
* oyvind.har...@zylin.com *
* *
+ * Copyright (C) 2009 Michael Schwingen *
+ * mich...@schwingen.org *
+ * *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
@@ -3384,6 +3387,65 @@
}
+int xscale_handle_vector_table_command(command_context_t *cmd_ctx, char *cmd, char **args, int argc)
+{
+ target_t *target = get_current_target(cmd_ctx);
+ armv4_5_common_t *armv4_5;
+ xscale_common_t *xscale;
+ int err = 0;
+
+ if (xscale_get_arch_pointers(target, armv4_5, xscale) != ERROR_OK)
+ {
+ return ERROR_OK;
+ }
+
+ if (argc == 0) /* print current settings */
+ {
+ int idx;
+
+ command_print(cmd_ctx, active user-set static vectors:);
+ for (idx = 1; idx 8; idx++)
+ if (xscale-static_low_vectors_set (1 idx))
+command_print(cmd_ctx, low %d: 0x%x, idx, xscale-static_low_vectors[idx]);
+ for (idx = 1; idx 8; idx++)
+ if (xscale-static_high_vectors_set (1 idx))
+command_print(cmd_ctx, high %d: 0x%x, idx, xscale-static_high_vectors[idx]);
+ return ERROR_OK;
+ }
+
+ if (argc != 3)
+ err = 1;
+ else
+ {
+ int idx;
+ uint32_t vec;
+ idx = strtoul(args[1], NULL, 0);
+ vec = strtoul(args[2], NULL, 0);
+
+ if (idx 1 || idx = 8)
+ err = 1;
+
+ if (!err strcmp(args[0], low) == 0)
+ {
+ xscale-static_low_vectors_set |= (1idx);
+ xscale-static_low_vectors[idx] = vec;
+ }
+ else if (!err (strcmp(args[0], high) == 0))
+ {
+ xscale-static_high_vectors_set |= (1idx);
+ xscale-static_high_vectors[idx] = vec;
+ }
+ else
+ err = 1;
+ }
+
+ if (err)
+ command_print(cmd_ctx, usage: xscale vector_table high|low index code);
+
+ return ERROR_OK;
+}
+
+
int xscale_handle_trace_buffer_command(struct command_context_s *cmd_ctx, char *cmd, char **args, int argc)
{
target_t *target = get_current_target(cmd_ctx);
@@ -3692,6 +3754,7 @@
register_command(cmd_ctx, xscale_cmd, dcache, xscale_handle_idcache_command, COMMAND_EXEC, ['enable'|'disable'] the DCache);
register_command(cmd_ctx, xscale_cmd, vector_catch, xscale_handle_vector_catch_command, COMMAND_EXEC, mask of vectors that should be catched);
+ register_command(cmd_ctx, xscale_cmd, vector_table, xscale_handle_vector_table_command, COMMAND_EXEC, high|low index code set static code for exception handler entry);
register_command(cmd_ctx, xscale_cmd, trace_buffer, xscale_handle_trace_buffer_command, COMMAND_EXEC, enable | disable ['fill' [n]|'wrap']);
Index: doc/openocd.texi
===
--- doc/openocd.texi (revision 2606)
+++ doc/openocd.texi (working copy)
@@ -4877,6 +4877,52 @@
@subsection XScale specific commands
@cindex XScale
+Some notes about the debug implementation on the XScale CPUs:
+
+The XScale CPU provides a special debug-only mini-instruction cache
+(mini-IC) in which exception vectors and target-resident debug handler
+code are placed by OpenOCD. In order to get access to the CPU, OpenOCD
+must point vector 0 (the reset vector) to the entry of the debug
+handler. However, this means that the complete first cacheline in the
+mini-IC is marked valid, which makes the CPU fetch all exception
+handlers from the mini-IC, ignoring the code in RAM.
+
+OpenOCD currently does not sync the mini-IC entries with the RAM
+contents (which would fail anyway while the target is running), so
+the user must provide appropriate values using the @code{xscale
+vector_table} command.
+
+It is recommended to place a pc-relative indirect branch in the vector
+table, and put
