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Peter Zijlstra
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perf/arch: Remove perf_sample_data::regs_user_copy
struct perf_sample_data lives on-stack, we should be careful about it's size. Furthermore, the pt_regs copy in there is only because x86_64 is a trainwreck, solve it differently. Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Steven Rostedt <rostedt@goodmis.org> Link: https://lkml.kernel.org/r/20201030151955.258178461@infradead.org
1 parent 09da9c8 commit 76a4efa

10 files changed

Lines changed: 22 additions & 31 deletions

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‎arch/arm/kernel/perf_regs.c‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -32,8 +32,7 @@ u64 perf_reg_abi(struct task_struct *task)
3232
}
3333

3434
void perf_get_regs_user(struct perf_regs *regs_user,
35-
struct pt_regs *regs,
36-
struct pt_regs *regs_user_copy)
35+
struct pt_regs *regs)
3736
{
3837
regs_user->regs = task_pt_regs(current);
3938
regs_user->abi = perf_reg_abi(current);

‎arch/arm64/kernel/perf_regs.c‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -73,8 +73,7 @@ u64 perf_reg_abi(struct task_struct *task)
7373
}
7474

7575
void perf_get_regs_user(struct perf_regs *regs_user,
76-
struct pt_regs *regs,
77-
struct pt_regs *regs_user_copy)
76+
struct pt_regs *regs)
7877
{
7978
regs_user->regs = task_pt_regs(current);
8079
regs_user->abi = perf_reg_abi(current);

‎arch/csky/kernel/perf_regs.c‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -32,8 +32,7 @@ u64 perf_reg_abi(struct task_struct *task)
3232
}
3333

3434
void perf_get_regs_user(struct perf_regs *regs_user,
35-
struct pt_regs *regs,
36-
struct pt_regs *regs_user_copy)
35+
struct pt_regs *regs)
3736
{
3837
regs_user->regs = task_pt_regs(current);
3938
regs_user->abi = perf_reg_abi(current);

‎arch/powerpc/perf/perf_regs.c‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -144,8 +144,7 @@ u64 perf_reg_abi(struct task_struct *task)
144144
}
145145

146146
void perf_get_regs_user(struct perf_regs *regs_user,
147-
struct pt_regs *regs,
148-
struct pt_regs *regs_user_copy)
147+
struct pt_regs *regs)
149148
{
150149
regs_user->regs = task_pt_regs(current);
151150
regs_user->abi = (regs_user->regs) ? perf_reg_abi(current) :

‎arch/riscv/kernel/perf_regs.c‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -36,8 +36,7 @@ u64 perf_reg_abi(struct task_struct *task)
3636
}
3737

3838
void perf_get_regs_user(struct perf_regs *regs_user,
39-
struct pt_regs *regs,
40-
struct pt_regs *regs_user_copy)
39+
struct pt_regs *regs)
4140
{
4241
regs_user->regs = task_pt_regs(current);
4342
regs_user->abi = perf_reg_abi(current);

‎arch/s390/kernel/perf_regs.c‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -53,8 +53,7 @@ u64 perf_reg_abi(struct task_struct *task)
5353
}
5454

5555
void perf_get_regs_user(struct perf_regs *regs_user,
56-
struct pt_regs *regs,
57-
struct pt_regs *regs_user_copy)
56+
struct pt_regs *regs)
5857
{
5958
/*
6059
* Use the regs from the first interruption and let

‎arch/x86/kernel/perf_regs.c‎

Lines changed: 11 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -101,8 +101,7 @@ u64 perf_reg_abi(struct task_struct *task)
101101
}
102102

103103
void perf_get_regs_user(struct perf_regs *regs_user,
104-
struct pt_regs *regs,
105-
struct pt_regs *regs_user_copy)
104+
struct pt_regs *regs)
106105
{
107106
regs_user->regs = task_pt_regs(current);
108107
regs_user->abi = perf_reg_abi(current);
@@ -129,12 +128,20 @@ u64 perf_reg_abi(struct task_struct *task)
129128
return PERF_SAMPLE_REGS_ABI_64;
130129
}
131130

131+
static DEFINE_PER_CPU(struct pt_regs, nmi_user_regs);
132+
132133
void perf_get_regs_user(struct perf_regs *regs_user,
133-
struct pt_regs *regs,
134-
struct pt_regs *regs_user_copy)
134+
struct pt_regs *regs)
135135
{
136+
struct pt_regs *regs_user_copy = this_cpu_ptr(&nmi_user_regs);
136137
struct pt_regs *user_regs = task_pt_regs(current);
137138

139+
if (!in_nmi()) {
140+
regs_user->regs = user_regs;
141+
regs_user->abi = perf_reg_abi(current);
142+
return;
143+
}
144+
138145
/*
139146
* If we're in an NMI that interrupted task_pt_regs setup, then
140147
* we can't sample user regs at all. This check isn't really

‎include/linux/perf_event.h‎

Lines changed: 0 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1022,13 +1022,7 @@ struct perf_sample_data {
10221022
struct perf_callchain_entry *callchain;
10231023
u64 aux_size;
10241024

1025-
/*
1026-
* regs_user may point to task_pt_regs or to regs_user_copy, depending
1027-
* on arch details.
1028-
*/
10291025
struct perf_regs regs_user;
1030-
struct pt_regs regs_user_copy;
1031-
10321026
struct perf_regs regs_intr;
10331027
u64 stack_user_size;
10341028

‎include/linux/perf_regs.h‎

Lines changed: 2 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -20,8 +20,7 @@ u64 perf_reg_value(struct pt_regs *regs, int idx);
2020
int perf_reg_validate(u64 mask);
2121
u64 perf_reg_abi(struct task_struct *task);
2222
void perf_get_regs_user(struct perf_regs *regs_user,
23-
struct pt_regs *regs,
24-
struct pt_regs *regs_user_copy);
23+
struct pt_regs *regs);
2524
#else
2625

2726
#define PERF_REG_EXTENDED_MASK 0
@@ -42,8 +41,7 @@ static inline u64 perf_reg_abi(struct task_struct *task)
4241
}
4342

4443
static inline void perf_get_regs_user(struct perf_regs *regs_user,
45-
struct pt_regs *regs,
46-
struct pt_regs *regs_user_copy)
44+
struct pt_regs *regs)
4745
{
4846
regs_user->regs = task_pt_regs(current);
4947
regs_user->abi = perf_reg_abi(current);

‎kernel/events/core.c‎

Lines changed: 3 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -6374,14 +6374,13 @@ perf_output_sample_regs(struct perf_output_handle *handle,
63746374
}
63756375

63766376
static void perf_sample_regs_user(struct perf_regs *regs_user,
6377-
struct pt_regs *regs,
6378-
struct pt_regs *regs_user_copy)
6377+
struct pt_regs *regs)
63796378
{
63806379
if (user_mode(regs)) {
63816380
regs_user->abi = perf_reg_abi(current);
63826381
regs_user->regs = regs;
63836382
} else if (!(current->flags & PF_KTHREAD)) {
6384-
perf_get_regs_user(regs_user, regs, regs_user_copy);
6383+
perf_get_regs_user(regs_user, regs);
63856384
} else {
63866385
regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
63876386
regs_user->regs = NULL;
@@ -7083,8 +7082,7 @@ void perf_prepare_sample(struct perf_event_header *header,
70837082
}
70847083

70857084
if (sample_type & (PERF_SAMPLE_REGS_USER | PERF_SAMPLE_STACK_USER))
7086-
perf_sample_regs_user(&data->regs_user, regs,
7087-
&data->regs_user_copy);
7085+
perf_sample_regs_user(&data->regs_user, regs);
70887086

70897087
if (sample_type & PERF_SAMPLE_REGS_USER) {
70907088
/* regs dump ABI info */

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