Date: Mon, 14 Dec 2015 10:06:01 +0000 (UTC) From: Andrew Turner <andrew@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r292194 - head/sys/arm64/arm64 Message-ID: <201512141006.tBEA61cP027292@repo.freebsd.org>
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Author: andrew Date: Mon Dec 14 10:06:01 2015 New Revision: 292194 URL: https://svnweb.freebsd.org/changeset/base/292194 Log: Skip restoring more registers when returning from an exception taken in the kernel. These registers are all callee saved, and as such will be restored before returning to the exception handler. Userland still needs these registers to be restored as they may be changed by the kernel and we don't currently track these places. Modified: head/sys/arm64/arm64/exception.S Modified: head/sys/arm64/arm64/exception.S ============================================================================== --- head/sys/arm64/arm64/exception.S Mon Dec 14 10:04:57 2015 (r292193) +++ head/sys/arm64/arm64/exception.S Mon Dec 14 10:06:01 2015 (r292194) @@ -90,15 +90,19 @@ __FBSDID("$FreeBSD$"); ldp x14, x15, [sp, #(TF_X + 14 * 8)] ldp x16, x17, [sp, #(TF_X + 16 * 8)] .if \el == 0 + /* + * We only restore the callee saved registers when returning to + * userland as they may have been updated by a system call or signal. + */ ldp x18, x19, [sp, #(TF_X + 18 * 8)] -.else - ldr x19, [sp, #(TF_X + 19 * 8)] -.endif ldp x20, x21, [sp, #(TF_X + 20 * 8)] ldp x22, x23, [sp, #(TF_X + 22 * 8)] ldp x24, x25, [sp, #(TF_X + 24 * 8)] ldp x26, x27, [sp, #(TF_X + 26 * 8)] ldp x28, x29, [sp, #(TF_X + 28 * 8)] +.else + ldr x29, [sp, #(TF_X + 29 * 8)] +.endif .if \el == 0 add sp, sp, #(TF_SIZE + 16) .else
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