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authorPaul Mackerras <paulus@ozlabs.org>2016-04-13 21:31:24 +1000
committerMichael Ellerman <mpe@ellerman.id.au>2016-05-11 21:54:07 +1000
commit31cdd0c39c7544ced79da53aa0b7e989f3a39582 (patch)
treea867018ed54a6b51784a0fde4b42faaf551ac889 /arch/powerpc/xmon/Makefile
parentf47822078dece7189cad0a5f472f148e5e916736 (diff)
powerpc/xmon: Fix SPR read/write commands and add command to dump SPRs
xmon has commands for reading and writing SPRs, but they don't work currently for several reasons. They attempt to synthesize a small function containing an mfspr or mtspr instruction and call it. However, the instructions are on the stack, which is usually not executable. Also, for 64-bit we set up a procedure descriptor, which is fine for the big-endian ABIv1, but not correct for ABIv2. Finally, the code uses the infrastructure for catching memory errors, but that only catches data storage interrupts and machine check interrupts, but a failed mfspr/mtspr can generate a program interrupt or a hypervisor emulation assist interrupt, or be a no-op. Instead of trying to synthesize a function on the fly, this adds two new functions, xmon_mfspr() and xmon_mtspr(), which take an SPR number as an argument and read or write the SPR. Because there is no Power ISA instruction which takes an SPR number in a register, we have to generate one of each possible mfspr and mtspr instruction, for all 1024 possible SPRs. Thus we get just over 8k bytes of code for each of xmon_mfspr() and xmon_mtspr(). However, this 16kB of code pales in comparison to the > 130kB of PPC opcode tables used by the xmon disassembler. To catch interrupts caused by the mfspr/mtspr instructions, we add a new 'catch_spr_faults' flag. If an interrupt occurs while it is set, we come back into xmon() via program_check_interrupt(), _exception() and die(), see that catch_spr_faults is set and do a longjmp to bus_error_jmp, back into read_spr() or write_spr(). This adds a couple of other nice features: first, a "Sa" command that attempts to read and print out the value of all 1024 SPRs. If any mfspr instruction acts as a no-op, then the SPR is not implemented and not printed. Secondly, the Sr and Sw commands detect when an SPR is not implemented (i.e. mfspr is a no-op) and print a message to that effect rather than printing a bogus value. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/xmon/Makefile')
-rw-r--r--arch/powerpc/xmon/Makefile2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/xmon/Makefile b/arch/powerpc/xmon/Makefile
index 436062dbb6e2..0b2f771593eb 100644
--- a/arch/powerpc/xmon/Makefile
+++ b/arch/powerpc/xmon/Makefile
@@ -7,7 +7,7 @@ UBSAN_SANITIZE := n
ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)
-obj-y += xmon.o nonstdio.o
+obj-y += xmon.o nonstdio.o spr_access.o
ifdef CONFIG_XMON_DISASSEMBLY
obj-y += ppc-dis.o ppc-opc.o