linux.git/arch/parisc/kernel/Makefile, branch v5.17

parisc: Enable TOC (transfer of contents) feature unconditionally

2022-01-11T10:57:37+00:00

Before this patch, the TOC code used a pre-allocated stack of 16kb for
each possible CPU. That space overhead was the reason why the TOC
feature wasn't enabled by default for 32-bit kernels.

This patch rewrites the TOC code to use a per-cpu stack. That way we use
much less memory now and as such we enable the TOC feature by default on
all kernels.

Additionally the dump of the registers and the stacktrace wasn't
serialized, which led to multiple CPUs printing the stack backtrace at
once which rendered the output unreadable.
Now the backtraces are nicely serialized by a lock.

Signed-off-by: Helge Deller

parisc: add support for TOC (transfer of control)

2021-11-01T06:35:59+00:00

Almost all PA-RISC machines have either a button that
is labeled with 'TOC' or a BMC function to trigger a TOC.
TOC is a non-maskable interrupt that is sent to the processor.
This can be used for diagnostic purposes like obtaining a
stack trace/register dump or to enter KDB/KGDB.

As an example, on my c8000, TOC can be used with:

CONFIG_KGDB=y
CONFIG_KGDB_KDB=y

and the 'kgdboc=ttyS0,115200' appended to the command line.

Press ^[( on serial console, which will enter the BMC command line,
and enter 'TOC s':

root@(none):/# (
cli>TOC s
Sending TOC/INIT.
 2800035d03e00000  0000000040c21ac8  CC_ERR_CHECK_TOC
 2800035d00e00000  0000000040c21ad0  CC_ERR_CHECK_TOC
 2800035d02e00000  0000000040c21ac8  CC_ERR_CHECK_TOC
 2800035d01e00000  0000000040c21ad0  CC_ERR_CHECK_TOC
 37000f7303e00000  2000000000000000  CC_ERR_CPU_CHECK_SUMMARY
 37000f7300e00000  2000000000000000  CC_ERR_CPU_CHECK_SUMMARY
 37000f7302e00000  2000000000000000  CC_ERR_CPU_CHECK_SUMMARY
 37000f7301e00000  2000000000000000  CC_ERR_CPU_CHECK_SUMMARY
 4300100803e00000  c0000000001d26cc  CC_MC_BR_TO_OS_TOC
 4300100800e00000  c0000000001d26cc  CC_MC_BR_TO_OS_TOC
 4300100802e00000  c0000000001d26cc  CC_MC_BR_TO_OS_TOC
 4300100801e00000  c0000000001d26cc  CC_MC_BR_TO_OS_TOC

Entering kdb (current=0x00000000411cef80, pid 0) on processor 0 due to NonMaskable Interrupt @ 0x40c21ad0
[0]kdb>

Signed-off-by: Sven Schnelle 
Signed-off-by: Helge Deller

parisc: fix compilation when KEXEC=n and KEXEC_FILE=y

2019-12-15T20:05:38+00:00

Fix compilation when the CONFIG_KEXEC_FILE=y and
CONFIG_KEXEC=n.

Reported-by: kbuild test robot 
Signed-off-by: Sven Schnelle 
Signed-off-by: Helge Deller

parisc: add support for kexec_file_load() syscall

2019-09-08T13:41:46+00:00

Signed-off-by: Sven Schnelle 
Signed-off-by: Helge Deller

parisc: add kexec syscall support

2019-09-08T13:37:04+00:00

Signed-off-by: Sven Schnelle 
Signed-off-by: Helge Deller

parisc: add dynamic ftrace

2019-06-08T10:56:29+00:00

This patch implements dynamic ftrace for PA-RISC. The required mcount
call sequences can get pretty long, so instead of patching the
whole call sequence out of the functions, we are using
-fpatchable-function-entry from gcc. This puts a configurable amount of
NOPS before/at the start of the function. Taking do_sys_open() as example,
which would look like this when the call is patched out:

1036b248:       08 00 02 40     nop
1036b24c:       08 00 02 40     nop
1036b250:       08 00 02 40     nop
1036b254:       08 00 02 40     nop

1036b258 :
1036b258:       08 00 02 40     nop
1036b25c:       08 03 02 41     copy r3,r1
1036b260:       6b c2 3f d9     stw rp,-14(sp)
1036b264:       08 1e 02 43     copy sp,r3
1036b268:       6f c1 01 00     stw,ma r1,80(sp)

When ftrace gets enabled for this function the kernel will patch these
NOPs to:

1036b248:       10 19 57 20     
1036b24c:       6f c1 00 80     stw,ma r1,40(sp)
1036b250:       48 21 3f d1     ldw -18(r1),r1
1036b254:       e8 20 c0 02     bv,n r0(r1)

1036b258 :
1036b258:       e8 3f 1f df     b,l,n .-c,r1
1036b25c:       08 03 02 41     copy r3,r1
1036b260:       6b c2 3f d9     stw rp,-14(sp)
1036b264:       08 1e 02 43     copy sp,r3
1036b268:       6f c1 01 00     stw,ma r1,80(sp)

So the first NOP in do_sys_open() will be patched to jump backwards into
some minimal trampoline code which pushes a stackframe, saves r1 which
holds the return address, loads the address of the real ftrace function,
and branches to that location. For 64 Bit things are getting a bit more
complicated (and longer) because we must make sure that the address of
ftrace location is 8 byte aligned, and the offset passed to ldd for
fetching the address is 8 byte aligned as well.

Note that gcc has a bug which misplaces the function label, and needs a
patch to make dynamic ftrace work. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90751 for details.

Signed-off-by: Sven Schnelle 
Signed-off-by: Helge Deller

parisc: Add static branch and JUMP_LABEL feature

2019-05-05T22:10:03+00:00

Signed-off-by: Helge Deller

parisc: Implement kprobes

2019-05-03T21:47:39+00:00

Implement kprobes support for PA-RISC.

Signed-off-by: Sven Schnelle 
Signed-off-by: Helge Deller

parisc: add KGDB support

2019-05-03T21:47:38+00:00

This patch add KGDB support to PA-RISC. It also implements
single-stepping utilizing the recovery counter.

Signed-off-by: Sven Schnelle 
Signed-off-by: Helge Deller

parisc: add parisc code patching

2019-05-03T21:47:38+00:00

Instead of re-mapping the whole kernel text with RWX rights
add a patch_text() which can be used to replace instructions
in the kernel .text section. Based on the ARM implementation.

Signed-off-by: Sven Schnelle 
Signed-off-by: Helge Deller