lwn.git/arch/s390/kernel/debug.c, branch docs-6.8

S390: Remove now superfluous sentinel elem from ctl_table arrays

2023-10-10T22:22:02+00:00

This commit comes at the tail end of a greater effort to remove the empty elements at the end of the ctl_table arrays (sentinels) which will reduce the overall build time size of the kernel and run time memory bloat by ~64 bytes per sentinel (further information Link : https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/) Remove the sentinel element from appldata_table, s390dbf_table, topology_ctl_table, cmm_table and page_table_sysctl. Reduced the memory allocation in appldata_register_ops by 1 effectively removing the sentinel from ops->ctl_table. This removal is safe because register_sysctl_sz and register_sysctl use the array size in addition to checking for the sentinel. Tested-by: Alexander Gordeev Acked-by: Heiko Carstens Signed-off-by: Joel Granados Signed-off-by: Luis Chamberlain

s390/debug: replace zero-length array with flexible-array member

2023-04-13T15:36:28+00:00

There are numerous patches which convert zero-length arrays with a flexible-array member. Convert the remaining s390 occurrences. Suggested-by: Gustavo A. R. Silva Link: https://github.com/KSPP/linux/issues/78 Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: simplify one-level syctl registration for s390dbf_table

2023-03-20T09:56:48+00:00

There is no need to declare an extra tables to just create directory, this can be easily be done with a prefix path with register_sysctl(). Simplify this registration. Signed-off-by: Luis Chamberlain Link: https://lore.kernel.org/r/20230310234525.3986352-3-mcgrof@kernel.org Reviewed-by: Vasily Gorbik Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens

s390/debug: remove function type cast

2022-11-23T15:24:07+00:00

clang warns about an incompatible function type cast: CC arch/s390/kernel/debug.o arch/s390/kernel/debug.c:142:2: error: cast from 'int (*)(debug_info_t *, struct debug_view *, char *, debug_sprintf_entry_t *)' (aka 'int (*)(struct debug_info *, struct debug_view *, char *, debug_sprintf_entry_t *)') to 'debug_format_proc_t *' (aka 'int (*)(struct debug_info *, struct debug_view *, char *, const char *)') converts to incompatible function type [-Werror,-Wcast-function-type-strict] (debug_format_proc_t *)&debug_sprintf_format_fn, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Get rid of this warning by changing debug_sprintf_format_fn() so it matches the debug_format_proc_t function type, and do the cast of the last parameter within the function itself. This is the standard way of handling such cases anyway. Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev

s390: move from strlcpy with unused retval to strscpy

2022-08-30T20:00:33+00:00

Follow the advice of the below link and prefer 'strscpy' in this subsystem. Conversion is 1:1 because the return value is not used. Generated by a coccinelle script. Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/ Signed-off-by: Wolfram Sang Acked-by: Jakub Kicinski Acked-by: Benjamin Block Acked-by: Alexandra Winter Link: https://lore.kernel.org/r/20220818205948.6360-1-wsa+renesas@sang-engineering.com Link: https://lore.kernel.org/r/20220818210102.7301-1-wsa+renesas@sang-engineering.com [gor@linux.ibm.com: squashed two changes linked above together] Signed-off-by: Vasily Gorbik

s390/sclp: add tracing of SCLP interactions

2021-08-25T09:03:35+00:00

Add tracing of interactions between the SCLP base driver, firmware and other drivers to support problem determination in case of SCLP-related issues. For that purpose this patch introduces two new s390dbf debug areas: - sclp: An abbreviated log of all common interactions - sclp_err: A full log of failed or abnormal interactions Tracing of full SCCB contents can be enabled for the sclp area by setting its debug level to maximum (6). Overview of added trace events: * Firmware interaction: - SRV1: Service call about to be issued - SRV2: Service call was issued - INT: Interrupt received * Driver interaction: - RQAD: Request was added - RQOK: Request success - RQAB: Request aborted - RQTM: Request timed out - REG: Event listener registered - UREG: Event listener unregistered - EVNT: Event callback - STCG: State-change callback * Abnormal events: - TMO: A timeout occurred - UNEX: Unexpected SCCB completion * Other (not traced at default level): - SYN1: Synchronous wait start - SYN2: Synchronous wait end Since the SCLP interface is used by console drivers this patch also moves s390dbf printks outside the critical section protected by debug area locks to prevent a potential deadlock that would otherwise be introduced between console_owner --> sclp_lock --> sclp_debug.lock. Signed-off-by: Peter Oberparleiter Signed-off-by: Heiko Carstens

s390/debug: add early tracing support

2021-08-25T09:03:35+00:00

Debug areas can currently only be used after s390dbf initialization which occurs as a postcore_initcall. This is too late for tracing earlier code such as that related to console_init(). This patch introduces a macro for defining a statically initialized debug area that can be used to trace very early code. The macro is made available for built-in code only because modules are never running during early boot. Example usage: 1. Define static debug area: DEFINE_STATIC_DEBUG_INFO(my_debug, "my_debug", 4, 1, 16, &debug_hex_ascii_view); 2. Add trace entry: debug_event(&my_debug, 0, "DATA", 4); Note: The debug area is automatically registered in debugfs during boot. A driver must not call any of the debug_register()/_unregister() functions on a static debug_info_t! Signed-off-by: Peter Oberparleiter Signed-off-by: Heiko Carstens

s390/debug: fix debug area life cycle

2021-08-25T09:03:35+00:00

Currently allocation and registration of s390dbf debug areas are tied together. As a result, a debug area cannot be unregistered and re-registered while any process has an associated debugfs file open. Fix this by splitting alloc/release from register/unregister. Signed-off-by: Peter Oberparleiter Signed-off-by: Heiko Carstens

s390/debug: keep debug data on resize

2021-08-25T09:03:35+00:00

Any previously recorded s390dbf debug data is reset when a debug area is resized using the 'pages' sysfs attribute. This can make live-debugging unnecessarily complex. Fix this by copying existing debug data to the newly allocated debug area when resizing. Signed-off-by: Peter Oberparleiter Signed-off-by: Heiko Carstens

s390/debug: Remove pointer obfuscation

2021-06-18T14:41:19+00:00

When read via debugfs, s390dbf debug-views print the kernel address of the call-site that created a trace entry. The kernel's %p pointer hashing feature obfuscates this address, and commit 860ec7c6e21c ("s390/debug: use pK for kernel pointers") made this obfuscation configurable via the kptr_restrict sysctl. Obfuscation of kernel address data printed via s390dbf debug-views does not add any additional protection since the associated debugfs files are only accessible to the root user that typically has enough other means to obtain kernel address data. Also trace payload data may contain binary representations of kernel addresses as part of logged data structues. Requiring such payload data to be obfuscated as well would be impractical and greatly diminish the use of s390dbf. Therefore completely remove pointer obfuscation from s390dbf debug-views. Reviewed-by: Steffen Maier Acked-by: Heiko Carstens Signed-off-by: Peter Oberparleiter Signed-off-by: Vasily Gorbik