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| author | Jason Wessel <jason.wessel@windriver.com> | 2010-05-21 04:04:30 +0200 |
|---|---|---|
| committer | Jason Wessel <jason.wessel@windriver.com> | 2010-05-21 04:04:30 +0200 |
| commit | 031acd8c42edd61070f81c51edc89e83147a3d0e (patch) | |
| tree | f0f848ca6b19ec049b00a430bb0fba1035acb76b | |
| parent | x86, kgdb, init: Add early and late debug states (diff) | |
| download | linux-031acd8c42edd61070f81c51edc89e83147a3d0e.tar.xz linux-031acd8c42edd61070f81c51edc89e83147a3d0e.zip | |
x86,kgdb: Implement early hardware breakpoint debugging
It is not possible to use the hw_breakpoint.c API prior to mm_init(),
but it is possible to use hardware breakpoints with the kernel
debugger.
Prior to smp_init() it is possible to simply write to the dr registers
of the boot cpu directly. This can be used up until the
kgdb_arch_late() is invoked, at which point the standard hw_breakpoint.c
API will get used.
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
| -rw-r--r-- | arch/x86/kernel/kgdb.c | 30 |
1 files changed, 28 insertions, 2 deletions
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 2b71ec41869f..4f4af75b9482 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -199,6 +199,8 @@ static struct hw_breakpoint { struct perf_event **pev; } breakinfo[4]; +static unsigned long early_dr7; + static void kgdb_correct_hw_break(void) { int breakno; @@ -210,6 +212,14 @@ static void kgdb_correct_hw_break(void) int cpu = raw_smp_processor_id(); if (!breakinfo[breakno].enabled) continue; + if (dbg_is_early) { + set_debugreg(breakinfo[breakno].addr, breakno); + early_dr7 |= encode_dr7(breakno, + breakinfo[breakno].len, + breakinfo[breakno].type); + set_debugreg(early_dr7, 7); + continue; + } bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu); info = counter_arch_bp(bp); if (bp->attr.disabled != 1) @@ -224,7 +234,8 @@ static void kgdb_correct_hw_break(void) if (!val) bp->attr.disabled = 0; } - hw_breakpoint_restore(); + if (!dbg_is_early) + hw_breakpoint_restore(); } static int hw_break_reserve_slot(int breakno) @@ -233,6 +244,9 @@ static int hw_break_reserve_slot(int breakno) int cnt = 0; struct perf_event **pevent; + if (dbg_is_early) + return 0; + for_each_online_cpu(cpu) { cnt++; pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); @@ -258,6 +272,9 @@ static int hw_break_release_slot(int breakno) struct perf_event **pevent; int cpu; + if (dbg_is_early) + return 0; + for_each_online_cpu(cpu) { pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); if (dbg_release_bp_slot(*pevent)) @@ -302,7 +319,11 @@ static void kgdb_remove_all_hw_break(void) bp = *per_cpu_ptr(breakinfo[i].pev, cpu); if (bp->attr.disabled == 1) continue; - arch_uninstall_hw_breakpoint(bp); + if (dbg_is_early) + early_dr7 &= ~encode_dr7(i, breakinfo[i].len, + breakinfo[i].type); + else + arch_uninstall_hw_breakpoint(bp); bp->attr.disabled = 1; } } @@ -379,6 +400,11 @@ void kgdb_disable_hw_debug(struct pt_regs *regs) for (i = 0; i < 4; i++) { if (!breakinfo[i].enabled) continue; + if (dbg_is_early) { + early_dr7 &= ~encode_dr7(i, breakinfo[i].len, + breakinfo[i].type); + continue; + } bp = *per_cpu_ptr(breakinfo[i].pev, cpu); if (bp->attr.disabled == 1) continue; |