Re: [Crash-utility] zram decompress support for gcore/crash-utility

-----Original Message----- From: crash-utility-bounces(a)redhat.com <crash-utility-bounces(a)redhat.com&gt; On Behalf Of ?乾利 Sent: Tuesday, March 31, 2020 9:49 AM To: crash-utility(a)redhat.com <crash-utility(a)redhat.com&gt; <crash-utility(a)redhat.com&gt; Subject: [Crash-utility] zram decompress support for gcore/crash-utility Hello list, When i try to use gcore to parse coredump from fulldump,I got below issue that make the coredump unavailable. 1. Zram is very common feature,in current android system supports zram swap,but gcore/crash-utility does not support,even zram swap can decoded from ram,many page fault due to this reason. I added zram decompress feature to gcore,and i’m also considering wheather support zram in crash-utility,but for this feature,i have to add miniLZO to codebase, I'm not sure if it's acceptable,plase help give some advice. miniLZO :miniLZO is a very lightweight subset of the LZO library,Distributed under the terms of the GNU General Public License <http://www.oberhumer.com/opensource/gpl.html> (GPL v2+). http://www.oberhumer.com/opensource/lzo/ <http://www.oberhumer.com/opensource/lzo/> This change is a bit big,I attached it to the mail,if attachment is not available,you can also see these patch in github: https://github.com/zhaoqianli0202/crash-gcore/commits/upstream <https://github.com/zhaoqianli0202/crash-gcore/commits/upstream> Please review. 2. For historical reasons,kernel reserved top 8/16 bytes of stacks,but after kernel-4.14, this reservation was cancelled,so gcore needs to improve compatibility. kernel change as below: commit 34be98f4944f99076f049a6806fc5f5207a755d3 Author: Ard Biesheuvel <ard.biesheuvel(a)linaro.org <mailto:ard.biesheuvel@linaro.org> > Date: Thu Jul 20 17:15:45 2017 +0100 arm64: kernel: remove {THREAD,IRQ_STACK}_START_SP For historical reasons, we leave the top 16 bytes of our task and IRQ stacks unused, a practice used to ensure that the SP can always be masked to find the base of the current stack (historically, where thread_info could be found).™ ==== Patch for this issue: commit d1031df4617351a58b8edfb0121c306baaa34f9d Author: zhaoqianli <zhaoqianli(a)xiaomi.com&gt; Date: Mon Mar 30 12:07:02 2020 +0800 gcore: ARM/ARM64 reserved 8/16 byte in the top of stacks before 4.14, but this reservation was removed after 4.14 Without this patch,gcore counld't parse full callstack in version after 4.14 diff --git a/gcore.c b/gcore.c index f75701d..f6e1787 100644 --- a/gcore.c +++ b/gcore.c @@ -558,4 +558,16 @@ static void gcore_machdep_init(void) if (!gcore_arch_vsyscall_has_vm_alwaysdump_flag()) gcore_machdep->vm_alwaysdump = 0x00000000; + +#if defined(ARM) || defined(ARM64) +#ifdef ARM +#define STACK_RESERVE_SIZE 8 +#else +#define STACK_RESERVE_SIZE 16 +#endif + if (THIS_KERNEL_VERSION >= LINUX(4,14,0)) + gcore_machdep->stack_reserve = 0; + else + gcore_machdep->stack_reserve = STACK_RESERVE_SIZE; +#endif } diff --git a/libgcore/gcore_arm.c b/libgcore/gcore_arm.c index 891d01e..c8aefdf 100644 --- a/libgcore/gcore_arm.c +++ b/libgcore/gcore_arm.c @@ -29,7 +29,7 @@ static int gpr_get(struct task_context *target, BZERO(regs, sizeof(*regs)); - readmem(machdep->get_stacktop(target->task) - 8 - SIZE(pt_regs), KVADDR, + readmem(machdep->get_stacktop(target->task) - gcore_machdep->stack_reserve - SIZE(pt_regs), KVADDR, regs, SIZE(pt_regs), "genregs_get: pt_regs", gcore_verbose_error_handle()); diff --git a/libgcore/gcore_arm64.c b/libgcore/gcore_arm64.c index 3257389..ed3fdc8 100644 --- a/libgcore/gcore_arm64.c +++ b/libgcore/gcore_arm64.c @@ -28,7 +28,7 @@ static int gpr_get(struct task_context *target, BZERO(regs, sizeof(*regs)); - readmem(machdep->get_stacktop(target->task) - 16 - SIZE(pt_regs), KVADDR, + readmem(machdep->get_stacktop(target->task) - gcore_machdep->stack_reserve - SIZE(pt_regs), KVADDR, regs, sizeof(struct user_pt_regs), "gpr_get: user_pt_regs", gcore_verbose_error_handle()); @@ -124,7 +124,7 @@ static int compat_gpr_get(struct task_context *target, BZERO(&pt_regs, sizeof(pt_regs)); BZERO(regs, sizeof(*regs)); - readmem(machdep->get_stacktop(target->task) - 16 - SIZE(pt_regs), KVADDR, + readmem(machdep->get_stacktop(target->task) - gcore_machdep->stack_reserve - SIZE(pt_regs), KVADDR, &pt_regs, sizeof(struct pt_regs), "compat_gpr_get: pt_regs", gcore_verbose_error_handle()); diff --git a/libgcore/gcore_defs.h b/libgcore/gcore_defs.h index b0f5603..f31036c 100644 --- a/libgcore/gcore_defs.h +++ b/libgcore/gcore_defs.h @@ -1177,6 +1177,7 @@ extern struct gcore_size_table gcore_size_table; struct gcore_machdep_table { ulong vm_alwaysdump; + uint8_t stack_reserve; }; #/******本邮件及其附件含有小米公司的保密信息，仅限于发送给上面地址中列出的个人或群组。禁止任何其他人以任何形式 使用（包括但不限于全部或部分地泄露、复制、或散发）本邮件中的信息。如果您错收了本邮件，请您立即电话或邮件通知 发件人并删除本邮件！ This e-mail and its attachments contain confidential information from XIAOMI, which is intended only for the person or entity whose address is listed above. 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