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hw & arm: simplify TLB permission bits via bitsets 

ref #1006
This commit is contained in:
Martin Stein 2013-12-19 17:32:53 +01:00 committed by Norman Feske
parent 864189762c
commit 6fcdbf5e9e
1 changed files with 29 additions and 70 deletions
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99
base-hw/src/core/tlb/arm.h
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@ -33,70 +33,29 @@ namespace Arm
return a == ((a >> alignm_log2) << alignm_log2); }
/**
* Common access permission [1:0] bitfield values
*/
struct Ap_1_0_bitfield
{
enum {
KERNEL_AND_USER_NO_ACCESS = 0,
USER_NO_ACCESS = 1,
USER_RO_ACCESS = 2,
KERNEL_AND_USER_SAME_ACCESS = 3
};
};
/**
* Common access permission [2] bitfield values
*/
struct Ap_2_bitfield
{
enum {
KERNEL_RW_OR_NO_ACCESS = 0,
KERNEL_RO_ACCESS = 1
};
};
/**
* Permission configuration according to given access rights
* Return permission configuration according to given mapping flags
*
* \param T targeted translation-table-descriptor type
* \param w see 'Section_table::insert_translation'
* \param x see 'Section_table::insert_translation'
* \param k see 'Section_table::insert_translation'
* \param T targeted translation-table-descriptor type
* \param flags mapping flags
*
* \return descriptor value with requested perms and the rest left zero
* \return descriptor value with AP and XN set and the rest left zero
*/
template <typename T>
static typename T::access_t
access_permission_bits(Page_flags const &flags)
access_permission_bits(Page_flags const & flags)
{
/* lookup table for AP bitfield values according to 'w' and 'k' flag */
typedef typename T::Ap_1_0 Ap_1_0;
typedef typename T::Ap_2 Ap_2;
/*
* Note: Don't make 'ap_bits' static to avoid implicit use of 'cmpxchg'
* prior enabling the MMU.
*
* XXX Replace array with a simpler-to-grasp switch statement.
*/
typename T::access_t const ap_bits[2][2] = {{
Ap_1_0::bits(Ap_1_0::USER_RO_ACCESS) | /* -- */
Ap_2::bits(Ap_2::KERNEL_RW_OR_NO_ACCESS),
Ap_1_0::bits(Ap_1_0::USER_NO_ACCESS) | /* -k */
Ap_2::bits(Ap_2::KERNEL_RO_ACCESS) }, {
Ap_1_0::bits(Ap_1_0::KERNEL_AND_USER_SAME_ACCESS) | /* w- */
Ap_2::bits(Ap_2::KERNEL_RW_OR_NO_ACCESS),
Ap_1_0::bits(Ap_1_0::USER_NO_ACCESS) | /* wk */
Ap_2::bits(Ap_2::KERNEL_RW_OR_NO_ACCESS) }
};
/* combine XN and AP bitfield values according to the flags */
typedef typename T::Xn Xn;
return Xn::bits(!flags.executable) |
ap_bits[flags.writeable][flags.privileged];
typedef typename T::Ap Ap;
typedef typename T::access_t access_t;
bool const w = flags.writeable;
bool const p = flags.privileged;
access_t ap;
if (w) { if (p) { ap = Ap::bits(0b001); }
else { ap = Ap::bits(0b011); }
} else { if (p) { ap = Ap::bits(0b101); }
else { ap = Ap::bits(0b010); }
}
return Xn::bits(!flags.executable) | ap;
}
/**
@ -104,7 +63,7 @@ namespace Arm
*/
template <typename T>
static typename T::access_t
memory_region_attr(Page_flags const &flags);
memory_region_attr(Page_flags const & flags);
/**
* Second level translation table
@ -228,19 +187,19 @@ namespace Arm
struct Xn : Bitfield<0, 1> { }; /* execute never */
struct B : Bitfield<2, 1> { }; /* mem region attr. */
struct C : Bitfield<3, 1> { }; /* mem region attr. */
struct Ap_1_0 : Bitfield<4, 2>, /* access permission */
Ap_1_0_bitfield { };
struct Ap_0 : Bitfield<4, 2> { }; /* access permission */
struct Tex : Bitfield<6, 3> { }; /* mem region attr. */
struct Ap_2 : Bitfield<9, 1>, /* access permission */
Ap_2_bitfield { };
struct Ap_1 : Bitfield<9, 1> { }; /* access permission */
struct S : Bitfield<10, 1> { }; /* shareable bit */
struct Ng : Bitfield<11, 1> { }; /* not global bit */
struct Pa_31_12 : Bitfield<12, 20> { }; /* physical base */
struct Ap : Bitset_2<Ap_0, Ap_1> { }; /* access permission */
/**
* Compose descriptor value
*/
static access_t create(Page_flags const &flags,
static access_t create(Page_flags const & flags,
addr_t const pa)
{
access_t v = access_permission_bits<Small_page>(flags) |
@ -322,7 +281,7 @@ namespace Arm
*/
void insert_translation(addr_t const vo, addr_t const pa,
size_t const size_log2,
Page_flags const &flags)
Page_flags const & flags)
{
/* validate virtual address */
unsigned i;
@ -570,19 +529,19 @@ namespace Arm
struct C : Bitfield<3, 1> { }; /* mem. region attr. */
struct Xn : Bitfield<4, 1> { }; /* execute never bit */
struct Domain : Bitfield<5, 4> { }; /* domain */
struct Ap_1_0 : Bitfield<10, 2>, /* access permission */
Ap_1_0_bitfield { };
struct Ap_0 : Bitfield<10, 2> { }; /* access permission */
struct Tex : Bitfield<12, 3> { }; /* mem. region attr. */
struct Ap_2 : Bitfield<15, 1>, /* access permission */
Ap_2_bitfield { };
struct Ap_1 : Bitfield<15, 1> { }; /* access permission */
struct S : Bitfield<16, 1> { }; /* shared */
struct Ng : Bitfield<17, 1> { }; /* not global */
struct Pa_31_20 : Bitfield<20, 12> { }; /* physical base */
struct Ap : Bitset_2<Ap_0, Ap_1> { }; /* access permission */
/**
* Compose descriptor value
*/
static access_t create(Page_flags const &flags,
static access_t create(Page_flags const & flags,
addr_t const pa)
{
access_t v = access_permission_bits<Section>(flags) |
@ -687,7 +646,7 @@ namespace Arm
template <typename ST>
size_t insert_translation(addr_t const vo, addr_t const pa,
size_t const size_log2,
Page_flags const &flags,
Page_flags const & flags,
ST * const st,
void * const extra_space = 0)
{