Introduce a new ARM64 "--machdep vabits_actual=<value>" command

line option for Linux 5.4 and later dumpfiles, which require the kernel's dynamically-determined "vabits_actual" value for virtual address translation. Without the patch, the crash session fails during initialization with the error message "crash: cannot determine VA_BITS_ACTUAL". This option will become unnecessary when the proposed TCR_EL1.T1SZ vmcoreinfo entry entry is incorporated into the kernel. ([email protected])
crash-utility · Apr 2, 2020 · d379b47 · d379b47
1 parent 8c28b56
commit d379b47
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diff --git a/arm64.c b/arm64.c
@@ -747,6 +747,8 @@ arm64_parse_machdep_arg_l(char *argstring, char *param, ulong *value)
 
 		if (STRNEQ(argstring, "max_physmem_bits")) {
 			*value = dtol(p, flags, &err);
+		} else if (STRNEQ(argstring, "vabits_actual")) {
+			*value = dtol(p, flags, &err);
 		} else if (megabytes) {
 			*value = dtol(p, flags, &err);
 			if (!err)
@@ -816,6 +818,12 @@ arm64_parse_cmdline_args(void)
 					"setting max_physmem_bits to: %ld\n\n",
 					machdep->max_physmem_bits);
 				continue;
+			} else if (arm64_parse_machdep_arg_l(arglist[i], "vabits_actual",
+			        &machdep->machspec->VA_BITS_ACTUAL)) {
+				error(NOTE,
+					"setting vabits_actual to: %ld\n\n",
+					machdep->machspec->VA_BITS_ACTUAL);
+				continue;
 			}
 
 			error(WARNING, "ignoring --machdep option: %s\n",
@@ -3890,6 +3898,9 @@ arm64_calc_VA_BITS(void)
 				machdep->machspec->VA_BITS_ACTUAL = value;
 				machdep->machspec->VA_BITS = value;
 				machdep->machspec->VA_START = _VA_START(machdep->machspec->VA_BITS_ACTUAL);
+			} else if (machdep->machspec->VA_BITS_ACTUAL) {
+				machdep->machspec->VA_BITS = machdep->machspec->VA_BITS_ACTUAL;
+				machdep->machspec->VA_START = _VA_START(machdep->machspec->VA_BITS_ACTUAL);
 			} else
 				error(FATAL, "cannot determine VA_BITS_ACTUAL\n");
 		}

diff --git a/crash.8 b/crash.8
@@ -280,6 +280,7 @@ ARM64:
   phys_offset=<physical-address>
   kimage_voffset=<kimage_voffset-value>
   max_physmem_bits=<value>
+  vabits_actual=<value>
 X86:
   page_offset=<CONFIG_PAGE_OFFSET-value>
 .fi

diff --git a/help.c b/help.c
@@ -181,6 +181,7 @@ char *program_usage_info[] = {
     "      phys_offset=<physical-address>",
     "      kimage_voffset=<kimage_voffset-value>",
     "      max_physmem_bits=<value>",
+    "      vabits_actual=<value>",
     "    X86:",
     "      page_offset=<CONFIG_PAGE_OFFSET-value>",
     "",