From 57c7ea513f0e4b033ba602550992e2ca0e6b8d2c Mon Sep 17 00:00:00 2001 From: Alex Smith Date: Thu, 1 May 2014 12:51:19 +0100 Subject: [PATCH] MIPS: ptrace: Avoid smp_processor_id() in preemptible code ptrace_{get,set}_watch_regs access current_cpu_data to get the watch register count/masks, which calls smp_processor_id(). However they are run in preemptible context and therefore trigger warnings like so: [ 6340.092000] BUG: using smp_processor_id() in preemptible [00000000] code: gdb/367 [ 6340.092000] caller is ptrace_get_watch_regs+0x44/0x220 Since the watch register count/masks should be the same across all CPUs, use boot_cpu_data instead. Note that this may need to change in future should a heterogenous system be supported where the count/masks are not the same across all CPUs (the current code is also incorrect for this scenario - current_cpu_data here would not necessarily be correct for the CPU that the target task will execute on). Signed-off-by: Alex Smith Reviewed-by: Paul Burton Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/6879/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/ptrace.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c index 71f85f427034..f639ccd5060c 100644 --- a/arch/mips/kernel/ptrace.c +++ b/arch/mips/kernel/ptrace.c @@ -163,7 +163,7 @@ int ptrace_get_watch_regs(struct task_struct *child, enum pt_watch_style style; int i; - if (!cpu_has_watch || current_cpu_data.watch_reg_use_cnt == 0) + if (!cpu_has_watch || boot_cpu_data.watch_reg_use_cnt == 0) return -EIO; if (!access_ok(VERIFY_WRITE, addr, sizeof(struct pt_watch_regs))) return -EIO; @@ -177,14 +177,14 @@ int ptrace_get_watch_regs(struct task_struct *child, #endif __put_user(style, &addr->style); - __put_user(current_cpu_data.watch_reg_use_cnt, + __put_user(boot_cpu_data.watch_reg_use_cnt, &addr->WATCH_STYLE.num_valid); - for (i = 0; i < current_cpu_data.watch_reg_use_cnt; i++) { + for (i = 0; i < boot_cpu_data.watch_reg_use_cnt; i++) { __put_user(child->thread.watch.mips3264.watchlo[i], &addr->WATCH_STYLE.watchlo[i]); __put_user(child->thread.watch.mips3264.watchhi[i] & 0xfff, &addr->WATCH_STYLE.watchhi[i]); - __put_user(current_cpu_data.watch_reg_masks[i], + __put_user(boot_cpu_data.watch_reg_masks[i], &addr->WATCH_STYLE.watch_masks[i]); } for (; i < 8; i++) { @@ -204,12 +204,12 @@ int ptrace_set_watch_regs(struct task_struct *child, unsigned long lt[NUM_WATCH_REGS]; u16 ht[NUM_WATCH_REGS]; - if (!cpu_has_watch || current_cpu_data.watch_reg_use_cnt == 0) + if (!cpu_has_watch || boot_cpu_data.watch_reg_use_cnt == 0) return -EIO; if (!access_ok(VERIFY_READ, addr, sizeof(struct pt_watch_regs))) return -EIO; /* Check the values. */ - for (i = 0; i < current_cpu_data.watch_reg_use_cnt; i++) { + for (i = 0; i < boot_cpu_data.watch_reg_use_cnt; i++) { __get_user(lt[i], &addr->WATCH_STYLE.watchlo[i]); #ifdef CONFIG_32BIT if (lt[i] & __UA_LIMIT) @@ -228,7 +228,7 @@ int ptrace_set_watch_regs(struct task_struct *child, return -EINVAL; } /* Install them. */ - for (i = 0; i < current_cpu_data.watch_reg_use_cnt; i++) { + for (i = 0; i < boot_cpu_data.watch_reg_use_cnt; i++) { if (lt[i] & 7) watch_active = 1; child->thread.watch.mips3264.watchlo[i] = lt[i]; -- 2.20.1