87 lines
3.4 KiB
Diff
87 lines
3.4 KiB
Diff
From: Alex Smith <alex.smith@imgtec.com>
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Date: Thu, 1 May 2014 12:51:19 +0100
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Subject: MIPS: ptrace: Avoid smp_processor_id() in preemptible code
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Origin: https://git.kernel.org/linus/57c7ea513f0e4b033ba602550992e2ca0e6b8d2c
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ptrace_{get,set}_watch_regs access current_cpu_data to get the watch
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register count/masks, which calls smp_processor_id(). However they are
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run in preemptible context and therefore trigger warnings like so:
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[ 6340.092000] BUG: using smp_processor_id() in preemptible [00000000] code: gdb/367
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[ 6340.092000] caller is ptrace_get_watch_regs+0x44/0x220
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Since the watch register count/masks should be the same across all
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CPUs, use boot_cpu_data instead. Note that this may need to change in
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future should a heterogenous system be supported where the count/masks
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are not the same across all CPUs (the current code is also incorrect
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for this scenario - current_cpu_data here would not necessarily be
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correct for the CPU that the target task will execute on).
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Signed-off-by: Alex Smith <alex.smith@imgtec.com>
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Reviewed-by: Paul Burton <paul.burton@imgtec.com>
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Cc: linux-mips@linux-mips.org
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Patchwork: https://patchwork.linux-mips.org/patch/6879/
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Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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---
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arch/mips/kernel/ptrace.c | 14 +++++++-------
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1 file changed, 7 insertions(+), 7 deletions(-)
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diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
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index 71f85f4..f639ccd 100644
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--- a/arch/mips/kernel/ptrace.c
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+++ b/arch/mips/kernel/ptrace.c
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@@ -163,7 +163,7 @@ int ptrace_get_watch_regs(struct task_struct *child,
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enum pt_watch_style style;
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int i;
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- if (!cpu_has_watch || current_cpu_data.watch_reg_use_cnt == 0)
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+ if (!cpu_has_watch || boot_cpu_data.watch_reg_use_cnt == 0)
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return -EIO;
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if (!access_ok(VERIFY_WRITE, addr, sizeof(struct pt_watch_regs)))
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return -EIO;
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@@ -177,14 +177,14 @@ int ptrace_get_watch_regs(struct task_struct *child,
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#endif
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__put_user(style, &addr->style);
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- __put_user(current_cpu_data.watch_reg_use_cnt,
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+ __put_user(boot_cpu_data.watch_reg_use_cnt,
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&addr->WATCH_STYLE.num_valid);
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- for (i = 0; i < current_cpu_data.watch_reg_use_cnt; i++) {
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+ for (i = 0; i < boot_cpu_data.watch_reg_use_cnt; i++) {
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__put_user(child->thread.watch.mips3264.watchlo[i],
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&addr->WATCH_STYLE.watchlo[i]);
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__put_user(child->thread.watch.mips3264.watchhi[i] & 0xfff,
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&addr->WATCH_STYLE.watchhi[i]);
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- __put_user(current_cpu_data.watch_reg_masks[i],
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+ __put_user(boot_cpu_data.watch_reg_masks[i],
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&addr->WATCH_STYLE.watch_masks[i]);
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}
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for (; i < 8; i++) {
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@@ -204,12 +204,12 @@ int ptrace_set_watch_regs(struct task_struct *child,
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unsigned long lt[NUM_WATCH_REGS];
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u16 ht[NUM_WATCH_REGS];
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- if (!cpu_has_watch || current_cpu_data.watch_reg_use_cnt == 0)
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+ if (!cpu_has_watch || boot_cpu_data.watch_reg_use_cnt == 0)
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return -EIO;
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if (!access_ok(VERIFY_READ, addr, sizeof(struct pt_watch_regs)))
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return -EIO;
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/* Check the values. */
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- for (i = 0; i < current_cpu_data.watch_reg_use_cnt; i++) {
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+ for (i = 0; i < boot_cpu_data.watch_reg_use_cnt; i++) {
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__get_user(lt[i], &addr->WATCH_STYLE.watchlo[i]);
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#ifdef CONFIG_32BIT
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if (lt[i] & __UA_LIMIT)
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@@ -228,7 +228,7 @@ int ptrace_set_watch_regs(struct task_struct *child,
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return -EINVAL;
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}
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/* Install them. */
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- for (i = 0; i < current_cpu_data.watch_reg_use_cnt; i++) {
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+ for (i = 0; i < boot_cpu_data.watch_reg_use_cnt; i++) {
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if (lt[i] & 7)
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watch_active = 1;
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child->thread.watch.mips3264.watchlo[i] = lt[i];
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--
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2.0.0
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