On 14.03.23 09:49, HAGIO KAZUHITO(萩尾 一仁) wrote:
Hi Juergen,thank you for the patches. On 2023/03/13 22:01, Juergen Gross wrote:Since many years now the stack address of each percpu stack is available via the stack_base[] array now. Use that instead of the indirect method via the percpu variables tss_init or tss_page, especially as the layout of tss_page has changed in Xen 4.16, resulting in the stack no longer to be found. Signed-off-by: Juergen Gross <jgr...@suse.com> --- xen_hyper.c | 50 ++++++++++++++++++++++++++++++-------------------- 1 file changed, 30 insertions(+), 20 deletions(-) diff --git a/xen_hyper.c b/xen_hyper.c index 1030c0a..72720e2 100644 --- a/xen_hyper.c +++ b/xen_hyper.c @@ -324,7 +324,7 @@ void xen_hyper_x86_pcpu_init(void) { ulong cpu_info; - ulong init_tss_base, init_tss; + ulong init_tss_base, init_tss, stack_base; ulong sp; struct xen_hyper_pcpu_context *pcc; char *buf, *bp; @@ -340,34 +340,44 @@ xen_hyper_x86_pcpu_init(void) } /* get physical cpu context */ xen_hyper_alloc_pcpu_context_space(XEN_HYPER_MAX_CPUS()); - if (symbol_exists("per_cpu__init_tss")) { + if (symbol_exists("stack_base")) { + stack_base = symbol_value("stack_base"); + flag = 0; + } else if (symbol_exists("per_cpu__init_tss")) { init_tss_base = symbol_value("per_cpu__init_tss"); - flag = TRUE; + flag = 1; } else if (symbol_exists("per_cpu__tss_page")) { init_tss_base = symbol_value("per_cpu__tss_page"); - flag = TRUE; + flag = 1; } else { init_tss_base = symbol_value("init_tss"); - flag = FALSE; + flag = 2; } buf = GETBUF(XEN_HYPER_SIZE(tss)); for_cpu_indexes(i, cpuid) { - if (flag) - init_tss = xen_hyper_per_cpu(init_tss_base, cpuid); - else - init_tss = init_tss_base + - XEN_HYPER_SIZE(tss) * cpuid; - if (!readmem(init_tss, KVADDR, buf, - XEN_HYPER_SIZE(tss), "init_tss", RETURN_ON_ERROR)) { - error(FATAL, "cannot read init_tss.\n"); - } - if (machine_type("X86")) { - sp = ULONG(buf + XEN_HYPER_OFFSET(tss_esp0)); - } else if (machine_type("X86_64")) { - sp = ULONG(buf + XEN_HYPER_OFFSET(tss_rsp0)); - } else - sp = 0; + if (flag) { + if (flag == 1) + init_tss = xen_hyper_per_cpu(init_tss_base, cpuid); + else + init_tss = init_tss_base + + XEN_HYPER_SIZE(tss) * cpuid; + if (!readmem(init_tss, KVADDR, buf, + XEN_HYPER_SIZE(tss), "init_tss", RETURN_ON_ERROR)) { + error(FATAL, "cannot read init_tss.\n"); + } + if (machine_type("X86")) { + sp = ULONG(buf + XEN_HYPER_OFFSET(tss_esp0)); + } else if (machine_type("X86_64")) { + sp = ULONG(buf + XEN_HYPER_OFFSET(tss_rsp0)); + } else + sp = 0; + } else { + if (!readmem(stack_base + sizeof(ulong) * cpuid, KVADDR, &sp, + sizeof(ulong), "stack_base", RETURN_ON_ERROR)) { + error(FATAL, "cannot read stack_base.\n"); + } + } cpu_info = XEN_HYPER_GET_CPU_INFO(sp); if (CRASHDEBUG(1)) { fprintf(fp, "sp=%lx, cpu_info=%lx\n", sp, cpu_info);The following warning is emitted with the patch: $ make clean ; make warn ... cc -c -g -DX86_64 -DLZO -DSNAPPY -DZSTD -DGDB_10_2 xen_hyper.c -Wall -O2 -Wstrict-prototypes -Wmissing-prototypes -fstack-protector -Wformat-security xen_hyper.c: In function ‘xen_hyper_x86_pcpu_init’: xen_hyper.c:390:3: warning: ‘init_tss’ may be used uninitialized in this function [-Wmaybe-uninitialized] xen_hyper_store_pcpu_context_tss(pcc, init_tss, buf); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Assuming we have init_tss = 0 first, the buf also may be used as it is (filled by zero), then xen_hyper_store_pcpu_context_tss() looks meaningless. What about not calling it? if (init_tss) xen_hyper_store_pcpu_context_tss(pcc, init_tss, buf);
Fine with me. Juergen
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