[PATCH v2 19/28] arm64/sve: ptrace and ELF coredump support
From: Dave.Martin@arm.com (Dave Martin)
Date: 2017-09-06 18:16:35
Also in:
kvmarm, linux-arch
On Wed, Sep 06, 2017 at 04:21:50PM +0000, Okamoto, Takayuki wrote:
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Hi Dave, I am an engineer of the postK computer from Fujitsu. When I tried to read "max_vl" by ptrace with this patch on our local SVE simulator, it was read as zero. I think the cause of this incident is that "max_vl" is set as "header->vl" only on warning case in sve_init_header_from_task(). "max_vl" should be set up also on normal case, like the following patch.--- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c@@ -755,6 +755,8 @@ static void sve_init_header_from_task(struct user_sve_header *header, if (WARN_ON(!sve_vl_valid(sve_max_vl))) header->max_vl = header->vl; + else + header->max_vl = sve_max_vl; header->size = SVE_PT_SIZE(vq, header->flags); header->max_size = SVE_PT_SIZE(sve_vq_from_vl(header->max_vl),
Hi, thanks for reporting this. It looks like a refactoring mistake I made while removing BUG_ON()s, which I missed in my testing. Your fix looks correct and seems to work. For stylistic reasons, I may write it like this instead, but the effect should be the same: header->max_vl = sve_max_vl; if (WARN_ON(!sve_vl_valid(sve_max_vl)) header->max_vl = header->vl; Cheers ---Dave
Best regards, Takayuki Okamoto -----Original Message----- From: gdb-owner at sourceware.org [mailto:gdb-owner at sourceware.org] On Behalf Of Dave Martin Sent: Friday, September 1, 2017 2:01 AM To: linux-arm-kernel at lists.infradead.org Cc: Catalin Marinas <catalin.marinas@arm.com>; Will Deacon <redacted>; Ard Biesheuvel <redacted>; Alex Benn?e <redacted>; Szabolcs Nagy <redacted>; Richard Sandiford <redacted>; kvmarm at lists.cs.columbia.edu; libc-alpha at sourceware.org; linux-arch at vger.kernel.org; gdb at sourceware.org; Alan Hayward <redacted>; Yao Qi <redacted>; Oleg Nesterov <oleg@redhat.com>; Alexander Viro <viro@zeniv.linux.org.uk> Subject: [PATCH v2 19/28] arm64/sve: ptrace and ELF coredump support
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@@ -702,6 +737,210 @@ static int system_call_set(struct task_struct *target, return ret; } +#ifdef CONFIG_ARM64_SVE + +static void sve_init_header_from_task(struct user_sve_header *header, + struct task_struct *target) +{ + unsigned int vq; + + memset(header, 0, sizeof(*header)); + + header->flags = test_tsk_thread_flag(target, TIF_SVE) ? + SVE_PT_REGS_SVE : SVE_PT_REGS_FPSIMD; + if (test_tsk_thread_flag(target, TIF_SVE_VL_INHERIT)) + header->flags |= SVE_PT_VL_INHERIT; + + header->vl = target->thread.sve_vl; + vq = sve_vq_from_vl(header->vl); + + if (WARN_ON(!sve_vl_valid(sve_max_vl))) + header->max_vl = header->vl; + + header->size = SVE_PT_SIZE(vq, header->flags); + header->max_size = SVE_PT_SIZE(sve_vq_from_vl(header->max_vl), + SVE_PT_REGS_SVE); +}
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