Re: [PATCH] target/arm: Fix debugging of ARMv8M Secure code

[Richard Henderson]

On 4/7/23 17:01, pbartell@amazon.com wrote:
> From: Paul Bartell <pbartell@amazon.com>
>
> Revert changes to arm_cpu_get_phys_page_attrs_debug made in commit
> 4a35855682cebb89f9630b07aa9fd37c4e8c733b.
>
> Commit 4a35855682 modifies the arm_cpu_get_phys_page_attrs_debug function
> so that it calls get_phys_addr_with_struct rather than get_phys_addr, which
> leads to a variety of memory access errors when debugging secure state
> code on qemu ARMv8M targets with gdb.
>
> This commit fixes a variety of gdb memory access errors including:
> "error reading variable" and "Cannot access memory at address" when
> attempting to read any memory address via gdb.
>
> Signed-off-by: Paul Bartell <pbartell@amazon.com>
> ---
>   target/arm/ptw.c | 8 ++------
>   1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/target/arm/ptw.c b/target/arm/ptw.c
> index ec3f51782a..5a1339d38f 100644
> --- a/target/arm/ptw.c
> +++ b/target/arm/ptw.c
> @@ -2999,16 +2999,12 @@ hwaddr arm_cpu_get_phys_page_attrs_debug(CPUState *cs, 
> vaddr addr,
>   {
>       ARMCPU *cpu = ARM_CPU(cs);
>       CPUARMState *env = &cpu->env;
> -    S1Translate ptw = {
> -        .in_mmu_idx = arm_mmu_idx(env),
> -        .in_secure = arm_is_secure(env),
> -        .in_debug = true,

Nack.  This will now affect vcpu state by changing the contents of the softmmu tlb, as 
well as changing the contents of memory (!) via PTE access/dirty bit updates.

A more complete description of "a variety of ... errors", and the conditions under which 
they are produced, would be appreciated.

r~