DC invokes DC_FPU_START/END in multiple parts of the code; this can
create a situation where we invoke this FPU operation in a nested way or
exit too early. For avoiding this situation, this commit adds a
mechanism where dc_fpu_begin/end manages the access to
kernel_fpu_begin/end.
Change since V3:
- Rebase
Change since V2:
- Christian: Do not use this_cpu_* between get/put_cpu_ptr().
Change since V1:
- Use a better variable names
- Use get_cpu_ptr and put_cpu_ptr to better balance preemption enable
and disable
Cc: Harry Wentland <harry.wentland@xxxxxxx>
Cc: Anson Jacob <Anson.Jacob@xxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Hersen Wu <hersenxs.wu@xxxxxxx>
Cc: Aric Cyr <aric.cyr@xxxxxxx>
Cc: Jun Lei <jun.lei@xxxxxxx>
Cc: Dmytro Laktyushkin <dmytro.laktyushkin@xxxxxxx>
Cc: Qingqing Zhuo <qingqing.zhuo@xxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
---
.../amd/display/amdgpu_dm/amdgpu_dm_trace.h | 13 ++--
.../gpu/drm/amd/display/amdgpu_dm/dc_fpu.c | 77 +++++++++++++------
drivers/gpu/drm/amd/display/dc/dc_trace.h | 4 +-
3 files changed, 63 insertions(+), 31 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h
index 230bb12c405e..fdcaea22b456 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h
@@ -638,23 +638,26 @@ TRACE_EVENT(amdgpu_refresh_rate_track,
);
TRACE_EVENT(dcn_fpu,
- TP_PROTO(bool begin, const char *function, const int line),
- TP_ARGS(begin, function, line),
+ TP_PROTO(bool begin, const char *function, const int line, const int recursion_depth),
+ TP_ARGS(begin, function, line, recursion_depth),
TP_STRUCT__entry(
__field(bool, begin)
__field(const char *, function)
__field(int, line)
+ __field(int, recursion_depth)
),
TP_fast_assign(
__entry->begin = begin;
__entry->function = function;
__entry->line = line;
+ __entry->recursion_depth = recursion_depth;
),
- TP_printk("%s()+%d: %s",
+ TP_printk("%s: recursion_depth: %d: %s()+%d:",
+ __entry->begin ? "begin" : "end",
+ __entry->recursion_depth,
__entry->function,
- __entry->line,
- __entry->begin ? "begin" : "end"
+ __entry->line
)
);
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
index d4ab27bf8d04..33807d746e76 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
@@ -33,6 +33,19 @@
#include <asm/cputable.h>
#endif
+/**
+ * DOC: DC FPU manipulation overview
+ *
+ * DC core uses FPU operations in multiple parts of the code, which requires a
+ * more specialized way to manage these areas' entrance. To fulfill this
+ * requirement, we created some wrapper functions that encapsulate
+ * kernel_fpu_begin/end to better fit our need in the display component. In
+ * summary, in this file, you can find functions related to FPU operation
+ * management.
+ */
+
+static DEFINE_PER_CPU(int, fpu_recursion_depth);
+
/**
* dc_fpu_begin - Enables FPU protection
* @function_name: A string containing the function name for debug purposes
@@ -48,22 +61,30 @@
*/
void dc_fpu_begin(const char *function_name, const int line)
{
- TRACE_DCN_FPU(true, function_name, line);
+ int *pcpu;
+
+ pcpu = get_cpu_ptr(&fpu_recursion_depth);
+ *pcpu += 1;
+ if (*pcpu == 1) {
#if defined(CONFIG_X86)
- kernel_fpu_begin();
+ kernel_fpu_begin();
#elif defined(CONFIG_PPC64)
- if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
- preempt_disable();
- enable_kernel_vsx();
- } else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) {
- preempt_disable();
- enable_kernel_altivec();
- } else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) {
- preempt_disable();
- enable_kernel_fp();
- }
+ if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
+ preempt_disable();
+ enable_kernel_vsx();
+ } else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) {
+ preempt_disable();
+ enable_kernel_altivec();
+ } else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) {
+ preempt_disable();
+ enable_kernel_fp();
+ }
#endif
+ }
+
+ TRACE_DCN_FPU(true, function_name, line, *pcpu);
+ put_cpu_ptr(&fpu_recursion_depth);
}
/**
@@ -78,19 +99,27 @@ void dc_fpu_begin(const char *function_name, const int line)
*/
void dc_fpu_end(const char *function_name, const int line)
{
- TRACE_DCN_FPU(false, function_name, line);
+ int *pcpu;
+
+ pcpu = get_cpu_ptr(&fpu_recursion_depth);
+ *pcpu -= 1;
+ if (*pcpu <= 0) {
#if defined(CONFIG_X86)
- kernel_fpu_end();
+ kernel_fpu_end();
#elif defined(CONFIG_PPC64)
- if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
- disable_kernel_vsx();
- preempt_enable();
- } else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) {
- disable_kernel_altivec();
- preempt_enable();
- } else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) {
- disable_kernel_fp();
- preempt_enable();
- }
+ if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
+ disable_kernel_vsx();
+ preempt_enable();
+ } else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) {
+ disable_kernel_altivec();
+ preempt_enable();
+ } else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) {
+ disable_kernel_fp();
+ preempt_enable();
+ }
#endif
+ }
+
+ TRACE_DCN_FPU(false, function_name, line, *pcpu);
+ put_cpu_ptr(&fpu_recursion_depth);
}
diff --git a/drivers/gpu/drm/amd/display/dc/dc_trace.h b/drivers/gpu/drm/amd/display/dc/dc_trace.h
index d598ba697e45..c711797e5c9e 100644
--- a/drivers/gpu/drm/amd/display/dc/dc_trace.h
+++ b/drivers/gpu/drm/amd/display/dc/dc_trace.h
@@ -38,5 +38,5 @@
#define TRACE_DCN_CLOCK_STATE(dcn_clocks) \
trace_amdgpu_dm_dc_clocks_state(dcn_clocks)
-#define TRACE_DCN_FPU(begin, function, line) \
- trace_dcn_fpu(begin, function, line)
+#define TRACE_DCN_FPU(begin, function, line, ref_count) \
+ trace_dcn_fpu(begin, function, line, ref_count)
--
2.25.1
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