Re: [Crash-utility] RISCV64: Use va_kernel_pa_offset in VTOP()

Since RISC-V Linux v6.4, the commit 3335068f8721 ("riscv: Use PUD/P4D/PGD pages for the linear mapping") changes the phys_ram_base from the kernel_map.phys_addr to the start of DRAM.

The Crash's VTOP() still uses phys_ram_base and kernel_map.virt_addr to translate kernel virtual address, that made Crash boot failed with Linux v6.4 and later version. Let Linux export kernel_map.va_kernel_pa_offset in v6.5 and Crash can use "va_kernel_pa_offset" to translate the kernel virtual address in VTOP() correctly. Signed-off-by: Song Shuai <suagrfillet(a)gmail.com&gt; --- You can check/test the Linux changes from this link: https://github.com/sugarfillet/linux/commits/6.5-rc3-crash And I'll send the Linux changes to riscv/for-next If you're ok with this patch. --- defs.h | 4 ++-- riscv64.c | 22 ++++++++++++++++++++++ 2 files changed, 24 insertions(+), 2 deletions(-) diff --git a/defs.h b/defs.h index 358f365..46b9857 100644 --- a/defs.h +++ b/defs.h @@ -3662,8 +3662,7 @@ typedef signed int s32; ulong _X = X; \ (THIS_KERNEL_VERSION >= LINUX(5,13,0) && \ (_X) >= machdep->machspec->kernel_link_addr) ? \ - (((unsigned long)(_X)-(machdep->machspec->kernel_link_addr)) + \ - machdep->machspec->phys_base): \ + ((unsigned long)(_X)-(machdep->machspec->va_kernel_pa_offset)): \ (((unsigned long)(_X)-(machdep->kvbase)) + \ machdep->machspec->phys_base); \ }) @@ -7021,6 +7020,7 @@ struct machine_specific { ulong modules_vaddr; ulong modules_end; ulong kernel_link_addr; + ulong va_kernel_pa_offset; ulong _page_present; ulong _page_read; diff --git a/riscv64.c b/riscv64.c index 6b9a688..b9e50b4 100644 --- a/riscv64.c +++ b/riscv64.c @@ -418,6 +418,27 @@ error: error(FATAL, "cannot get vm layout\n"); } +static void +riscv64_get_va_kernel_pa_offset(struct machine_specific *ms) +{ + unsigned long kernel_version = riscv64_get_kernel_version(); + + /* + * va_kernel_pa_offset is defined in Linux kernel since 6.5. + */ + if (kernel_version >= LINUX(6,5,0)) { + char *string; + if ((string = pc->read_vmcoreinfo("NUMBER(va_kernel_pa_offset)"))) { + ms->va_kernel_pa_offset = htol(string, QUIET, NULL); + free(string); + } else + error(FATAL, "cannot read va_kernel_pa_offset\n"); + } else if (kernel_version >= LINUX(6,4,0)) + error(FATAL, "cannot determine va_kernel_pa_offset since Linux 6.4\n"); + else + ms->va_kernel_pa_offset = ms->kernel_link_addr - ms->phys_base; +} + static int riscv64_is_kvaddr(ulong vaddr) { @@ -1352,6 +1373,7 @@ riscv64_init(int when) riscv64_get_struct_page_size(machdep->machspec); riscv64_get_va_bits(machdep->machspec); riscv64_get_va_range(machdep->machspec); + riscv64_get_va_kernel_pa_offset(machdep->machspec); pt_level_alloc(&machdep->pgd, "cannot malloc pgd space."); pt_level_alloc(&machdep->machspec->p4d, "cannot malloc p4d space.");