From 5cd6fa6de5e903a9500d858fffbc72c574d4513b Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Fri, 26 Mar 2021 18:01:37 +0000 Subject: [PATCH] arm64: setup: name `tcr` register In __cpu_setup we conditionally manipulate the TCR_EL1 value in x10 after previously using x10 as a scratch register for unrelated temporary variables. To make this a bit clearer, let's move the TCR_EL1 value into a named register `tcr`. To simplify the register allocation, this is placed in the highest available caller-saved scratch register, tcr. Following the example of `mair`, we initialise the register with the default value prior to any feature discovery, and write it to MAIR_EL1 after all feature discovery is complete, which allows us to simplify the featuere discovery code. The existing `mte_tcr` register is no longer needed, and is replaced by the use of x10 as a temporary, matching the rest of the MTE feature discovery assembly in __cpu_setup. As x20 is no longer used, the function is now AAPCS compliant, as we've generally aimed for in our assembly functions. There should be no functional change as as a result of this patch. Signed-off-by: Mark Rutland Cc: Marc Zyngier Cc: Will Deacon Link: https://lore.kernel.org/r/20210326180137.43119-3-mark.rutland@arm.com Signed-off-by: Catalin Marinas --- arch/arm64/mm/proc.S | 39 ++++++++++++++++----------------------- 1 file changed, 16 insertions(+), 23 deletions(-) diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index f560b6f..0a48191 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -419,15 +419,17 @@ SYM_FUNC_START(__cpu_setup) reset_amuserenr_el0 x1 // Disable AMU access from EL0 /* - * Memory region attributes + * Default values for VMSA control registers. These will be adjusted + * below depending on detected CPU features. */ mair .req x17 + tcr .req x16 mov_q mair, MAIR_EL1_SET -#ifdef CONFIG_ARM64_MTE - mte_tcr .req x20 - - mov mte_tcr, #0 + mov_q tcr, TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \ + TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \ + TCR_TBI0 | TCR_A1 | TCR_KASAN_SW_FLAGS +#ifdef CONFIG_ARM64_MTE /* * Update MAIR_EL1, GCR_EL1 and TFSR*_EL1 if MTE is supported * (ID_AA64PFR1_EL1[11:8] > 1). @@ -450,36 +452,26 @@ SYM_FUNC_START(__cpu_setup) msr_s SYS_TFSRE0_EL1, xzr /* set the TCR_EL1 bits */ - mov_q mte_tcr, TCR_KASAN_HW_FLAGS + mov_q x10, TCR_KASAN_HW_FLAGS + orr tcr, tcr, x10 1: #endif - /* - * Set/prepare TCR and TTBR. TCR_EL1.T1SZ gets further - * adjusted if the kernel is compiled with 52bit VA support. - */ - mov_q x10, TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \ - TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \ - TCR_TBI0 | TCR_A1 | TCR_KASAN_SW_FLAGS -#ifdef CONFIG_ARM64_MTE - orr x10, x10, mte_tcr - .unreq mte_tcr -#endif - tcr_clear_errata_bits x10, x9, x5 + tcr_clear_errata_bits tcr, x9, x5 #ifdef CONFIG_ARM64_VA_BITS_52 ldr_l x9, vabits_actual sub x9, xzr, x9 add x9, x9, #64 - tcr_set_t1sz x10, x9 + tcr_set_t1sz tcr, x9 #else ldr_l x9, idmap_t0sz #endif - tcr_set_t0sz x10, x9 + tcr_set_t0sz tcr, x9 /* * Set the IPS bits in TCR_EL1. */ - tcr_compute_pa_size x10, #TCR_IPS_SHIFT, x5, x6 + tcr_compute_pa_size tcr, #TCR_IPS_SHIFT, x5, x6 #ifdef CONFIG_ARM64_HW_AFDBM /* * Enable hardware update of the Access Flags bit. @@ -489,11 +481,11 @@ SYM_FUNC_START(__cpu_setup) mrs x9, ID_AA64MMFR1_EL1 and x9, x9, #0xf cbz x9, 1f - orr x10, x10, #TCR_HA // hardware Access flag update + orr tcr, tcr, #TCR_HA // hardware Access flag update 1: #endif /* CONFIG_ARM64_HW_AFDBM */ msr mair_el1, mair - msr tcr_el1, x10 + msr tcr_el1, tcr /* * Prepare SCTLR */ @@ -501,4 +493,5 @@ SYM_FUNC_START(__cpu_setup) ret // return to head.S .unreq mair + .unreq tcr SYM_FUNC_END(__cpu_setup) -- 2.7.4