[Crash-utility PATCH V2] RISCV64: Add KASLR support
HAGIO KAZUHITO(萩尾 一仁)
k-hagio-ab at nec.com
Sun Aug 20 17:43:47 PDT 2023
On 2023/08/18 18:50, Song Shuai wrote:
> From: Song Shuai <suagrfillet at 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@rivosinc.com/
>
> Signed-off-by: Song Shuai <suagrfillet at gmail.com>
> Reviewed-by: Guo Ren <guoren at kernel.org>
>
> ---
> Changes since V1:
> https://lore.kernel.org/linux-riscv/20230815104800.705753-1-songshuaishuai@tinylab.org/
> - 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);
Thanks, applied.
https://github.com/crash-utility/crash/commit/1aa93cd33fa11f9d9bc9dc7e6a698d690fdd1bb3
Kazu
More information about the kexec
mailing list