[Crash-utility] [PATCH] Determine the ARM64 kernel's Pointer Authentication mask value by reading the new KERNELPACMASK vmcoreinfo entry.

This value is used to mask the PAC bits and generate correct backtrace. (amit.kachhap(a)arm.com) --- The kernel version for the corresponding vmcoreinfo entry is posted here[1]. [1]: https://lore.kernel.org/patchwork/patch/1211981/ arm64.c | 20 ++++++++++++++++++++ defs.h | 1 + 2 files changed, 21 insertions(+) diff --git a/arm64.c b/arm64.c index 09b1b76..55e084f 100644 --- a/arm64.c +++ b/arm64.c @@ -84,6 +84,7 @@ static int arm64_get_kvaddr_ranges(struct vaddr_range *); static void arm64_get_crash_notes(void); static void arm64_calc_VA_BITS(void); static int arm64_is_uvaddr(ulong, struct task_context *); +static void arm64_calc_KERNELPACMASK(void); /* @@ -213,6 +214,7 @@ arm64_init(int when) machdep->pagemask = ~((ulonglong)machdep->pageoffset); arm64_calc_VA_BITS(); + arm64_calc_KERNELPACMASK(); ms = machdep->machspec; if (ms->VA_BITS_ACTUAL) { ms->page_offset = ARM64_PAGE_OFFSET_ACTUAL; @@ -472,6 +474,7 @@ arm64_init(int when) case LOG_ONLY: machdep->machspec = &arm64_machine_specific; arm64_calc_VA_BITS(); + arm64_calc_KERNELPACMASK(); arm64_calc_phys_offset(); machdep->machspec->page_offset = ARM64_PAGE_OFFSET; break; @@ -1925,6 +1928,7 @@ arm64_print_stackframe_entry(struct bt_info *bt, int level, struct arm64_stackfr struct syment *sp; struct load_module *lm; char buf[BUFSIZE]; + struct machine_specific *ms = machdep->machspec; /* * if pc comes from a saved lr, it actually points to an instruction @@ -1932,6 +1936,9 @@ arm64_print_stackframe_entry(struct bt_info *bt, int level, struct arm64_stackfr * See, for example, "bl schedule" before ret_to_user(). */ branch_pc = frame->pc - 4; + if (ms->CONFIG_ARM64_KERNELPACMASK) + branch_pc |= ms->CONFIG_ARM64_KERNELPACMASK; + name = closest_symbol(branch_pc); name_plus_offset = NULL; @@ -4070,6 +4077,19 @@ arm64_swp_offset(ulong pte) return pte; } +static void arm64_calc_KERNELPACMASK(void) +{ + ulong value; + char *string; + + if ((string = pc->read_vmcoreinfo("NUMBER(KERNELPACMASK)"))) { + value = htol(string, QUIET, NULL); + free(string); + machdep->machspec->CONFIG_ARM64_KERNELPACMASK = value; + } + fprintf(fp, " got NUMBER(KERNELPACMASK) =%llx\n", value); +} + #endif /* ARM64 */ diff --git a/defs.h b/defs.h index a3f828d..f37a957 100644 --- a/defs.h +++ b/defs.h @@ -3269,6 +3269,7 @@ struct machine_specific { ulong machine_kexec_end; ulong VA_BITS_ACTUAL; ulong CONFIG_ARM64_VA_BITS; + ulong CONFIG_ARM64_KERNELPACMASK; ulong VA_START; }; -- 2.7.4