powerpc/hw_breakpoints: Rewrite 8xx breakpoints to allow any address range size.

Unlike standard powerpc, Powerpc 8xx doesn't have SPRN_DABR, but
it has a breakpoint support based on a set of comparators which
allow more flexibility.

Commit 4ad8622dc548 ("powerpc/8xx: Implement hw_breakpoint")
implemented breakpoints by emulating the DABR behaviour. It did
this by setting one comparator the match 4 bytes at breakpoint address
and the other comparator to match 4 bytes at breakpoint address + 4.

Rewrite 8xx hw_breakpoint to make breakpoints match all addresses
defined by the breakpoint address and length by making full use of
comparators.

Now, comparator E is set to match any address greater than breakpoint
address minus one. Comparator F is set to match any address lower than
breakpoint address plus breakpoint length. Addresses are aligned
to 32 bits.

When the breakpoint range starts at address 0, the breakpoint is set
to match comparator F only. When the breakpoint range end at address
0xffffffff, the breakpoint is set to match comparator E only.
Otherwise the breakpoint is set to match comparator E and F.

At the same time, use registers bit names instead of hardcoded values.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/05105deeaf63bc02151aea2cdeaf525534e0e9d4.1574790198.git.christophe.leroy@c-s.fr

1 files changed, 35 insertions, 22 deletions

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 4df94b6e2f32..7fcf72e58826 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -740,28 +740,6 @@ static inline int __set_dabr(unsigned long dabr, unsigned long dabrx)
 		mtspr(SPRN_DABRX, dabrx);
 	return 0;
 }
-#elif defined(CONFIG_PPC_8xx)
-static inline int __set_dabr(unsigned long dabr, unsigned long dabrx)
-{
-	unsigned long addr = dabr & ~HW_BRK_TYPE_DABR;
-	unsigned long lctrl1 = 0x90000000; /* compare type: equal on E & F */
-	unsigned long lctrl2 = 0x8e000002; /* watchpoint 1 on cmp E | F */
-
-	if ((dabr & HW_BRK_TYPE_RDWR) == HW_BRK_TYPE_READ)
-		lctrl1 |= 0xa0000;
-	else if ((dabr & HW_BRK_TYPE_RDWR) == HW_BRK_TYPE_WRITE)
-		lctrl1 |= 0xf0000;
-	else if ((dabr & HW_BRK_TYPE_RDWR) == 0)
-		lctrl2 = 0;
-
-	mtspr(SPRN_LCTRL2, 0);
-	mtspr(SPRN_CMPE, addr);
-	mtspr(SPRN_CMPF, addr + 4);
-	mtspr(SPRN_LCTRL1, lctrl1);
-	mtspr(SPRN_LCTRL2, lctrl2);
-
-	return 0;
-}
 #else
 static inline int __set_dabr(unsigned long dabr, unsigned long dabrx)
 {
@@ -782,6 +760,39 @@ static inline int set_dabr(struct arch_hw_breakpoint *brk)
 	return __set_dabr(dabr, dabrx);
 }
 
+static inline int set_breakpoint_8xx(struct arch_hw_breakpoint *brk)
+{
+	unsigned long lctrl1 = LCTRL1_CTE_GT | LCTRL1_CTF_LT | LCTRL1_CRWE_RW |
+			       LCTRL1_CRWF_RW;
+	unsigned long lctrl2 = LCTRL2_LW0EN | LCTRL2_LW0LADC | LCTRL2_SLW0EN;
+	unsigned long start_addr = brk->address & ~HW_BREAKPOINT_ALIGN;
+	unsigned long end_addr = (brk->address + brk->len - 1) | HW_BREAKPOINT_ALIGN;
+
+	if (start_addr == 0)
+		lctrl2 |= LCTRL2_LW0LA_F;
+	else if (end_addr == ~0U)
+		lctrl2 |= LCTRL2_LW0LA_E;
+	else
+		lctrl2 |= LCTRL2_LW0LA_EandF;
+
+	mtspr(SPRN_LCTRL2, 0);
+
+	if ((brk->type & HW_BRK_TYPE_RDWR) == 0)
+		return 0;
+
+	if ((brk->type & HW_BRK_TYPE_RDWR) == HW_BRK_TYPE_READ)
+		lctrl1 |= LCTRL1_CRWE_RO | LCTRL1_CRWF_RO;
+	if ((brk->type & HW_BRK_TYPE_RDWR) == HW_BRK_TYPE_WRITE)
+		lctrl1 |= LCTRL1_CRWE_WO | LCTRL1_CRWF_WO;
+
+	mtspr(SPRN_CMPE, start_addr - 1);
+	mtspr(SPRN_CMPF, end_addr + 1);
+	mtspr(SPRN_LCTRL1, lctrl1);
+	mtspr(SPRN_LCTRL2, lctrl2);
+
+	return 0;
+}
+
 void __set_breakpoint(struct arch_hw_breakpoint *brk)
 {
 	memcpy(this_cpu_ptr(&current_brk), brk, sizeof(*brk));
@@ -789,6 +800,8 @@ void __set_breakpoint(struct arch_hw_breakpoint *brk)
 	if (dawr_enabled())
 		// Power8 or later
 		set_dawr(brk);
+	else if (IS_ENABLED(CONFIG_PPC_8xx))
+		set_breakpoint_8xx(brk);
 	else if (!cpu_has_feature(CPU_FTR_ARCH_207S))
 		// Power7 or earlier
 		set_dabr(brk);