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Diffstat (limited to 'arch/mips/kernel/branch.c')
-rw-r--r--arch/mips/kernel/branch.c128
1 files changed, 84 insertions, 44 deletions
diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c
index 32103cc2a25..4d735d0e58f 100644
--- a/arch/mips/kernel/branch.c
+++ b/arch/mips/kernel/branch.c
@@ -9,6 +9,7 @@
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/signal.h>
+#include <linux/module.h>
#include <asm/branch.h>
#include <asm/cpu.h>
#include <asm/cpu-features.h>
@@ -17,28 +18,22 @@
#include <asm/ptrace.h>
#include <asm/uaccess.h>
-/*
- * Compute the return address and do emulate branch simulation, if required.
+/**
+ * __compute_return_epc_for_insn - Computes the return address and do emulate
+ * branch simulation, if required.
+ *
+ * @regs: Pointer to pt_regs
+ * @insn: branch instruction to decode
+ * @returns: -EFAULT on error and forces SIGBUS, and on success
+ * returns 0 or BRANCH_LIKELY_TAKEN as appropriate after
+ * evaluating the branch.
*/
-int __compute_return_epc(struct pt_regs *regs)
+int __compute_return_epc_for_insn(struct pt_regs *regs,
+ union mips_instruction insn)
{
- unsigned int __user *addr;
unsigned int bit, fcr31, dspcontrol;
- long epc;
- union mips_instruction insn;
-
- epc = regs->cp0_epc;
- if (epc & 3)
- goto unaligned;
-
- /*
- * Read the instruction
- */
- addr = (unsigned int __user *) epc;
- if (__get_user(insn.word, addr)) {
- force_sig(SIGSEGV, current);
- return -EFAULT;
- }
+ long epc = regs->cp0_epc;
+ int ret = 0;
switch (insn.i_format.opcode) {
/*
@@ -64,18 +59,22 @@ int __compute_return_epc(struct pt_regs *regs)
switch (insn.i_format.rt) {
case bltz_op:
case bltzl_op:
- if ((long)regs->regs[insn.i_format.rs] < 0)
+ if ((long)regs->regs[insn.i_format.rs] < 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == bltzl_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
case bgez_op:
case bgezl_op:
- if ((long)regs->regs[insn.i_format.rs] >= 0)
+ if ((long)regs->regs[insn.i_format.rs] >= 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == bgezl_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -83,9 +82,11 @@ int __compute_return_epc(struct pt_regs *regs)
case bltzal_op:
case bltzall_op:
regs->regs[31] = epc + 8;
- if ((long)regs->regs[insn.i_format.rs] < 0)
+ if ((long)regs->regs[insn.i_format.rs] < 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == bltzall_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -93,12 +94,15 @@ int __compute_return_epc(struct pt_regs *regs)
case bgezal_op:
case bgezall_op:
regs->regs[31] = epc + 8;
- if ((long)regs->regs[insn.i_format.rs] >= 0)
+ if ((long)regs->regs[insn.i_format.rs] >= 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == bgezall_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
+
case bposge32_op:
if (!cpu_has_dsp)
goto sigill;
@@ -133,9 +137,11 @@ int __compute_return_epc(struct pt_regs *regs)
case beq_op:
case beql_op:
if (regs->regs[insn.i_format.rs] ==
- regs->regs[insn.i_format.rt])
+ regs->regs[insn.i_format.rt]) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == beql_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -143,9 +149,11 @@ int __compute_return_epc(struct pt_regs *regs)
case bne_op:
case bnel_op:
if (regs->regs[insn.i_format.rs] !=
- regs->regs[insn.i_format.rt])
+ regs->regs[insn.i_format.rt]) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == bnel_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -153,9 +161,11 @@ int __compute_return_epc(struct pt_regs *regs)
case blez_op: /* not really i_format */
case blezl_op:
/* rt field assumed to be zero */
- if ((long)regs->regs[insn.i_format.rs] <= 0)
+ if ((long)regs->regs[insn.i_format.rs] <= 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == bnel_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -163,9 +173,11 @@ int __compute_return_epc(struct pt_regs *regs)
case bgtz_op:
case bgtzl_op:
/* rt field assumed to be zero */
- if ((long)regs->regs[insn.i_format.rs] > 0)
+ if ((long)regs->regs[insn.i_format.rs] > 0) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == bnel_op)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -187,18 +199,22 @@ int __compute_return_epc(struct pt_regs *regs)
switch (insn.i_format.rt & 3) {
case 0: /* bc1f */
case 2: /* bc1fl */
- if (~fcr31 & (1 << bit))
+ if (~fcr31 & (1 << bit)) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == 2)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
case 1: /* bc1t */
case 3: /* bc1tl */
- if (fcr31 & (1 << bit))
+ if (fcr31 & (1 << bit)) {
epc = epc + 4 + (insn.i_format.simmediate << 2);
- else
+ if (insn.i_format.rt == 3)
+ ret = BRANCH_LIKELY_TAKEN;
+ } else
epc += 8;
regs->cp0_epc = epc;
break;
@@ -239,15 +255,39 @@ int __compute_return_epc(struct pt_regs *regs)
#endif
}
- return 0;
+ return ret;
-unaligned:
- printk("%s: unaligned epc - sending SIGBUS.\n", current->comm);
+sigill:
+ printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm);
force_sig(SIGBUS, current);
return -EFAULT;
+}
+EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn);
-sigill:
- printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm);
+int __compute_return_epc(struct pt_regs *regs)
+{
+ unsigned int __user *addr;
+ long epc;
+ union mips_instruction insn;
+
+ epc = regs->cp0_epc;
+ if (epc & 3)
+ goto unaligned;
+
+ /*
+ * Read the instruction
+ */
+ addr = (unsigned int __user *) epc;
+ if (__get_user(insn.word, addr)) {
+ force_sig(SIGSEGV, current);
+ return -EFAULT;
+ }
+
+ return __compute_return_epc_for_insn(regs, insn);
+
+unaligned:
+ printk("%s: unaligned epc - sending SIGBUS.\n", current->comm);
force_sig(SIGBUS, current);
return -EFAULT;
+
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-30 18:35:29 +0000