Re: [PATCH] [RFC] arm64: enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION
From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2021-03-17 16:19:27
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On Wed, Mar 17, 2021 at 02:37:57PM +0000, Catalin Marinas wrote:
On Thu, Feb 25, 2021 at 12:20:56PM +0100, Arnd Bergmann wrote:quoted
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index bad2b9eaab22..926cdb597a45 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S@@ -217,7 +217,7 @@ SECTIONS INIT_CALLS CON_INITCALL INIT_RAM_FS - *(.init.altinstructions .init.bss .init.bss.*) /* from the EFI stub */ + *(.init.altinstructions .init.data.* .init.bss .init.bss.*) /* from the EFI stub */INIT_DATA already covers .init.data and .init.data.*, so I don't think we need this change.
Ah, INIT_DATA only covers init.data.* (so no dot in front). The above is needed for the EFI stub. However, I gave this a quick try and under Qemu with -cpu max and -smp 2 (or more) it fails as below. I haven't debugged but the lr points to just after the switch_to() call. Maybe some section got discarded and we patched in the wrong instructions. It is fine with -cpu host or -smp 1. -------------------8<------------------------ smp: Bringing up secondary CPUs ... Detected PIPT I-cache on CPU1 CPU1: Booted secondary processor 0x0000000001 [0x000f0510] Unable to handle kernel paging request at virtual address eb91d81ad2971160 Mem abort info: ESR = 0x86000004 EC = 0x21: IABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 [eb91d81ad2971160] address between user and kernel address ranges Internal error: Oops: 86000004 [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 16 Comm: migration/1 Not tainted 5.12.0-rc3-00002-g128e977c1322 #1 Stopper: 0x0 <- 0x0 pstate: 60000085 (nZCv daIf -PAN -UAO -TCO BTYPE=--) pc : 0xeb91d81ad2971160 lr : __schedule+0x230/0x6b8 sp : ffff80001009bd60 x29: ffff80001009bd60 x28: 0000000000000000 x27: ffff0000000a6760 x26: ffff0000000b7540 x25: 0080000000000000 x24: ffffd81ad3969000 x23: ffff0000000a6200 x22: 6ee0d81ad2971658 x21: ffff0000000a6200 x20: ffff000000080000 x19: ffff00007fbc6bc0 x18: 0000000000000030 x17: 0000000000000000 x16: 0000000000000000 x15: 00008952b30a9a9e x14: 0000000000000366 x13: 0000000000000192 x12: 0000000000000000 x11: 0000000000000003 x10: 00000000000009b0 x9 : ffff80001009bd30 x8 : ffff0000000a6c10 x7 : ffff00007fbc6cc0 x6 : 00000000fffedb30 x5 : 00000000ffffffff x4 : 0000000000000000 x3 : 0000000000000008 x2 : 0000000000000000 x1 : ffff0000000a6200 x0 : ffff0000000a3800 Call trace: 0xeb91d81ad2971160 schedule+0x70/0x108 schedule_preempt_disabled+0x24/0x40 __kthread_parkme+0x68/0xd0 kthread+0x138/0x170 ret_from_fork+0x10/0x30 Code: bad PC value ---[ end trace af3481062ecef3e7 ]--- -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel