From 777ab8d84442dd6c0c5fbf787de87779d5ab82e8 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Tue, 1 Mar 2022 11:59:48 -1000 Subject: [PATCH] target/arm: Prepare DBGBVR and DBGWVR for FEAT_LVA The original A.a revision of the AArch64 ARM required that we force-extend the addresses in these registers from 49 bits. This language has been loosened via a combination of IMPLEMENTATION DEFINED and CONSTRAINTED UNPREDICTABLE to allow consideration of the entire aligned address. This means that we do not have to consider whether or not FEAT_LVA is enabled, and decide from which bit an address might need to be extended. Reviewed-by: Peter Maydell Signed-off-by: Richard Henderson Message-id: 20220301215958.157011-9-richard.henderson@linaro.org Signed-off-by: Peter Maydell --- target/arm/helper.c | 32 ++++++++++++++++++++++++-------- 1 file changed, 24 insertions(+), 8 deletions(-) diff --git a/target/arm/helper.c b/target/arm/helper.c index c002100979..2eff30d18c 100644 --- a/target/arm/helper.c +++ b/target/arm/helper.c @@ -6423,11 +6423,18 @@ static void dbgwvr_write(CPUARMState *env, const ARMCPRegInfo *ri, ARMCPU *cpu = env_archcpu(env); int i = ri->crm; - /* Bits [63:49] are hardwired to the value of bit [48]; that is, the - * register reads and behaves as if values written are sign extended. + /* * Bits [1:0] are RES0. + * + * It is IMPLEMENTATION DEFINED whether [63:49] ([63:53] with FEAT_LVA) + * are hardwired to the value of bit [48] ([52] with FEAT_LVA), or if + * they contain the value written. It is CONSTRAINED UNPREDICTABLE + * whether the RESS bits are ignored when comparing an address. + * + * Therefore we are allowed to compare the entire register, which lets + * us avoid considering whether or not FEAT_LVA is actually enabled. */ - value = sextract64(value, 0, 49) & ~3ULL; + value &= ~3ULL; raw_write(env, ri, value); hw_watchpoint_update(cpu, i); @@ -6473,10 +6480,19 @@ void hw_breakpoint_update(ARMCPU *cpu, int n) case 0: /* unlinked address match */ case 1: /* linked address match */ { - /* Bits [63:49] are hardwired to the value of bit [48]; that is, - * we behave as if the register was sign extended. Bits [1:0] are - * RES0. The BAS field is used to allow setting breakpoints on 16 - * bit wide instructions; it is CONSTRAINED UNPREDICTABLE whether + /* + * Bits [1:0] are RES0. + * + * It is IMPLEMENTATION DEFINED whether bits [63:49] + * ([63:53] for FEAT_LVA) are hardwired to a copy of the sign bit + * of the VA field ([48] or [52] for FEAT_LVA), or whether the + * value is read as written. It is CONSTRAINED UNPREDICTABLE + * whether the RESS bits are ignored when comparing an address. + * Therefore we are allowed to compare the entire register, which + * lets us avoid considering whether FEAT_LVA is actually enabled. + * + * The BAS field is used to allow setting breakpoints on 16-bit + * wide instructions; it is CONSTRAINED UNPREDICTABLE whether * a bp will fire if the addresses covered by the bp and the addresses * covered by the insn overlap but the insn doesn't start at the * start of the bp address range. We choose to require the insn and @@ -6489,7 +6505,7 @@ void hw_breakpoint_update(ARMCPU *cpu, int n) * See also figure D2-3 in the v8 ARM ARM (DDI0487A.c). */ int bas = extract64(bcr, 5, 4); - addr = sextract64(bvr, 0, 49) & ~3ULL; + addr = bvr & ~3ULL; if (bas == 0) { return; }