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arm64: debug: refactor reinstall_suspended_bps()

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`reinstall_suspended_bps()` plays a key part in the stepping process
when we have hardware breakpoints and watchpoints enabled.
It checks if we need to step one, will re-enable it if it has
been handled and will return whether or not we need to proceed with
a single-step.

However, the current naming and return values make it harder to understand
the logic and goal of the function.

Rename it `try_step_suspended_breakpoints()` and change the return value
to a boolean, aligning it with similar functions used in
`do_el0_undef()` like `try_emulate_mrs()`, and making its behaviour
more obvious.

Signed-off-by: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Tested-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Will Deacon <will@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20250707114109.35672-9-ada.coupriediaz@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ada Couprie Diaz
2025-07-07 12:41:04 +01:00
committed by Will Deacon
parent 43e2ae77fc
commit 80691d3552
3 changed files with 16 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files
arch/arm64/include/asm/debug-monitors.h
+3 -3
View File
@@ -84,11 +84,11 @@ void kernel_rewind_single_step(struct pt_regs *regs);
void kernel_fastforward_single_step(struct pt_regs *regs);
#ifdef CONFIG_HAVE_HW_BREAKPOINT
int reinstall_suspended_bps(struct pt_regs *regs);
bool try_step_suspended_breakpoints(struct pt_regs *regs);
#else
static inline int reinstall_suspended_bps(struct pt_regs *regs)
static inline bool try_step_suspended_breakpoints(struct pt_regs *regs)
{
return -ENODEV;
return false;
}
#endif
arch/arm64/kernel/debug-monitors.c
+1 -1
View File
@@ -195,7 +195,7 @@ static int single_step_handler(unsigned long unused, unsigned long esr,
* If we are stepping a pending breakpoint, call the hw_breakpoint
* handler first.
*/
if (!reinstall_suspended_bps(regs))
if (try_step_suspended_breakpoints(regs))
return 0;
if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED)
arch/arm64/kernel/hw_breakpoint.c
+12 -13
View File
@@ -847,36 +847,35 @@ NOKPROBE_SYMBOL(watchpoint_handler);
/*
* Handle single-step exception.
*/
int reinstall_suspended_bps(struct pt_regs *regs)
bool try_step_suspended_breakpoints(struct pt_regs *regs)
{
struct debug_info *debug_info = &current->thread.debug;
int handled_exception = 0, *kernel_step;
kernel_step = this_cpu_ptr(&stepping_kernel_bp);
int *kernel_step = this_cpu_ptr(&stepping_kernel_bp);
bool handled_exception = false;
/*
* Called from single-step exception handler.
* Return 0 if execution can resume, 1 if a SIGTRAP should be
* reported.
* Return true if we stepped a breakpoint and can resume execution,
* false if we need to handle a single-step.
*/
if (user_mode(regs)) {
if (debug_info->bps_disabled) {
debug_info->bps_disabled = 0;
toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL0, 1);
handled_exception = 1;
handled_exception = true;
}
if (debug_info->wps_disabled) {
debug_info->wps_disabled = 0;
toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL0, 1);
handled_exception = 1;
handled_exception = true;
}
if (handled_exception) {
if (debug_info->suspended_step) {
debug_info->suspended_step = 0;
/* Allow exception handling to fall-through. */
handled_exception = 0;
handled_exception = false;
} else {
user_disable_single_step(current);
}
@@ -890,17 +889,17 @@ int reinstall_suspended_bps(struct pt_regs *regs)
if (*kernel_step != ARM_KERNEL_STEP_SUSPEND) {
kernel_disable_single_step();
handled_exception = 1;
handled_exception = true;
} else {
handled_exception = 0;
handled_exception = false;
}
*kernel_step = ARM_KERNEL_STEP_NONE;
}
return !handled_exception;
return handled_exception;
}
NOKPROBE_SYMBOL(reinstall_suspended_bps);
NOKPROBE_SYMBOL(try_step_suspended_breakpoints);
/*
* Context-switcher for restoring suspended breakpoints.