Re: [PATCH v2 27/37] arm64: mte: Switch GCR_EL1 in kernel entry and exit
From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2020-09-17 17:04:53
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On Thu, Sep 17, 2020 at 05:52:21PM +0100, Catalin Marinas wrote:
On Tue, Sep 15, 2020 at 11:16:09PM +0200, Andrey Konovalov wrote:quoted
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index ff34461524d4..79a6848840bd 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S@@ -175,6 +175,28 @@ alternative_else_nop_endif #endif .endm + .macro mte_restore_gcr, el, tsk, tmp, tmp2 +#ifdef CONFIG_ARM64_MTE +alternative_if_not ARM64_MTE + b 1f +alternative_else_nop_endif + .if \el == 0 + ldr \tmp, [\tsk, #THREAD_GCR_EL1_USER] + .else + ldr_l \tmp, gcr_kernel_excl + .endif + /* + * Calculate and set the exclude mask preserving + * the RRND (bit[16]) setting. + */ + mrs_s \tmp2, SYS_GCR_EL1 + bfi \tmp2, \tmp, #0, #16 + msr_s SYS_GCR_EL1, \tmp2 + isb +1: +#endif + .endm + .macro kernel_entry, el, regsize = 64 .if \regsize == 32 mov w0, w0 // zero upper 32 bits of x0@@ -214,6 +236,8 @@ alternative_else_nop_endif ptrauth_keys_install_kernel tsk, x20, x22, x23 + mte_restore_gcr 1, tsk, x22, x23 + scs_load tsk, x20 .else add x21, sp, #S_FRAME_SIZE@@ -332,6 +356,8 @@ alternative_else_nop_endif /* No kernel C function calls after this as user keys are set. */ ptrauth_keys_install_user tsk, x0, x1, x2 + mte_restore_gcr 0, tsk, x0, x1Some nitpicks on these macros to match the ptrauth_keys_* above. Define separate mte_set_{user,kernel}_gcr macros with a common mte_set_gcr that is used by both.
One more thing - the new mte_set_kernel_gcr should probably skip the GCR_EL1 update if KASAN_HW_TAGS is disabled. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel