4:50 a.m.
From: Song Shuai <suagrfillet(a)gmail.com>
This patch adds KASLR support for Crash to analyze KASLR-ed vmcore
since RISC-V Linux is already sufficiently prepared for KASLR [1].
With this patch, even if the Crash '--kaslr' option is not set or Linux
CONFIG_RANDOMIZE_BASE is not configured, the 'derive_kaslr_offset()'
function will always work to calculate 'kt->relocate' which serves to
update the kernel virtual address.
Testing in Qemu rv64 virt, kernel log outputed the kernel offset:
[ 121.214447] SMP: stopping secondary CPUs
[ 121.215445] Kernel Offset: 0x37c00000 from 0xffffffff80000000
[ 121.216312] Starting crashdump kernel...
[ 121.216585] Will call new kernel at 94800000 from hart id 0
[ 121.216834] FDT image at 9c7fd000
[ 121.216982] Bye...
Running crash with `-d 1` option and without `--kaslr` option,
we get the right `kt->relocate` and kernel link addr:
$ ../crash/crash -d 1 vmlinux vmcore_kaslr_0815
...
KASLR:
_stext from vmlinux: ffffffff80002000
_stext from vmcoreinfo: ffffffffb7c02000
relocate: 37c00000 (892MB)
vmemmap : 0xff1c000000000000 - 0xff20000000000000
vmalloc : 0xff20000000000000 - 0xff60000000000000
mudules : 0xffffffff3952f000 - 0xffffffffb7c00000
lowmem : 0xff60000000000000 -
kernel link addr : 0xffffffffb7c00000
...
KERNEL: /home/song/9_linux/linux/00_rv_kaslr/vmlinux
DUMPFILE: /tmp/hello/vmcore_kaslr_0815
CPUS: 2
DATE: Tue Aug 15 16:36:15 CST 2023
UPTIME: 00:02:01
LOAD AVERAGE: 0.40, 0.23, 0.09
TASKS: 63
NODENAME: stage4.fedoraproject.org
RELEASE: 6.5.0-rc3-00008-gad18dee423ac
VERSION: #17 SMP Tue Aug 15 14:41:12 CST 2023
MACHINE: riscv64 (unknown Mhz)
MEMORY: 511.8 MB
PANIC: "Kernel panic - not syncing: sysrq triggered crash"
PID: 160
COMMAND: "bash"
TASK: ff6000000152bac0 [THREAD_INFO: ff6000000152bac0]
CPU: 1
STATE: TASK_RUNNING (PANIC)
crash>
[1]: https://lore.kernel.org/linux-riscv/20230722123850.634544-1-alexghiti@riv...
Signed-off-by: Song Shuai <suagrfillet(a)gmail.com>
Reviewed-by: Guo Ren <guoren(a)kernel.org>
---
Changes since V1:
https://lore.kernel.org/linux-riscv/20230815104800.705753-1-songshuaishua...
- supplement the output of my Crash test in the commit-msg
- add the Reviewed-by from Guo
---
main.c | 2 +-
riscv64.c | 11 +++++++++++
symbols.c | 4 ++--
3 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/main.c b/main.c
index b278c22..0c6e595 100644
--- a/main.c
+++ b/main.c
@@ -228,7 +228,7 @@ main(int argc, char **argv)
} else if (STREQ(long_options[option_index].name, "kaslr")) {
if (!machine_type("X86_64") &&
!machine_type("ARM64") && !machine_type("X86")
&&
- !machine_type("S390X"))
+ !machine_type("S390X") && !machine_type("RISCV64"))
error(INFO, "--kaslr not valid "
"with this machine type.\n");
else if (STREQ(optarg, "auto"))
diff --git a/riscv64.c b/riscv64.c
index a02f75a..288c7ae 100644
--- a/riscv64.c
+++ b/riscv64.c
@@ -378,6 +378,9 @@ static void riscv64_get_va_range(struct machine_specific *ms)
} else
goto error;
+ if ((kt->flags2 & KASLR) && (kt->flags & RELOC_SET))
+ ms->kernel_link_addr += (kt->relocate * -1);
+
/*
* From Linux 5.13, the kernel mapping is moved to the last 2GB
* of the address space, modules use the 2GB memory range right
@@ -1360,6 +1363,14 @@ riscv64_init(int when)
machdep->verify_paddr = generic_verify_paddr;
machdep->ptrs_per_pgd = PTRS_PER_PGD;
+
+ /*
+ * Even if CONFIG_RANDOMIZE_BASE is not configured,
+ * derive_kaslr_offset() should work and set
+ * kt->relocate to 0
+ */
+ if (!kt->relocate && !(kt->flags2 & (RELOC_AUTO|KASLR)))
+ kt->flags2 |= (RELOC_AUTO|KASLR);
break;
case PRE_GDB:
diff --git a/symbols.c b/symbols.c
index 876be7a..8e8b4c3 100644
--- a/symbols.c
+++ b/symbols.c
@@ -629,7 +629,7 @@ kaslr_init(void)
char *string;
if ((!machine_type("X86_64") && !machine_type("ARM64")
&& !machine_type("X86") &&
- !machine_type("S390X")) || (kt->flags & RELOC_SET))
+ !machine_type("S390X") && !machine_type("RISCV64")) ||
(kt->flags & RELOC_SET))
return;
if (!kt->vmcoreinfo._stext_SYMBOL &&
@@ -795,7 +795,7 @@ store_symbols(bfd *abfd, int dynamic, void *minisyms, long symcount,
} else if (!(kt->flags & RELOC_SET))
kt->flags |= RELOC_FORCE;
} else if (machine_type("X86_64") || machine_type("ARM64") ||
- machine_type("S390X")) {
+ machine_type("S390X") || machine_type("RISCV64")) {
if ((kt->flags2 & RELOC_AUTO) && !(kt->flags & RELOC_SET))
derive_kaslr_offset(abfd, dynamic, from,
fromend, size, store);
--
2.20.1